Home › Calculators › Generator Size Calculator
Generator Size Calculator
List the appliances you want to run with their running and starting watts. The calculator adds up the running load, finds the peak when the biggest motor starts, applies a safety margin and suggests a generator size.
Starting watts are optional (use the running watts if the item has no motor). Use “2 x Heater, 1500” for quantities.
%
10-25% is common to avoid running at full load
Enter your values to see the result.
Advertisement
Advertisement
How to use the Generator Size Calculator
- List your appliances, one per line: name, running watts, starting watts.
- Use the label or manual for exact watts, or the typical values in the reference table.
- Set a safety margin (20% is a good default).
- Read the recommended size and the starting watts the generator must handle.
- Copy or download your load list.
Typical appliance wattage (estimates)
Use your appliance's label whenever possible. These are common ballpark figures; actual values vary by model.
| Appliance | Running watts | Starting watts |
|---|---|---|
| Refrigerator / freezer | 600-800 | 1,800-2,200 |
| Sump pump (1/2 hp) | 1,000-1,050 | 2,000-2,200 |
| Furnace fan (1/3 hp) | 700 | 1,400 |
| Window air conditioner (10,000 BTU) | 1,200 | 3,600 |
| Central air conditioner (3 ton) | 3,500-4,000 | 10,000+ |
| Well pump (1 hp) | 1,000 | 2,000-4,000 |
| Microwave (1,000 W) | 1,000 | — |
| Space heater | 1,500 | — |
| Electric water heater | 4,000-4,500 | — |
| Television | 100-250 | — |
| LED light bulb | 8-15 each | — |
| Laptop / phone charger | 20-100 | — |
The sizing method
- Running load = sum of the running watts of everything on at the same time.
- Peak load = running load + (starting − running watts) of the item with the biggest surge.
- Add a margin: multiply both by 1.1 to 1.25.
- Pick a generator whose rated (running) watts ≥ the running requirement and whose starting watts ≥ the peak requirement.
Safety: run portable generators outdoors only, far from doors and windows, because exhaust contains carbon monoxide. Connect a generator to home wiring only through a transfer switch installed by a qualified electrician.
Frequently asked questions
How do I calculate what size generator I need?
Add the running watts of everything you want to run at the same time. Then find the appliance with the largest difference between starting and running watts and add that extra surge. Choose a generator whose running watts cover the total and whose starting watts cover the peak, plus a safety margin.
What is the difference between running and starting watts?
Running (rated) watts are what an appliance uses continuously. Motors and compressors, such as fridges, pumps and air conditioners, need two to three times more power for a second or two when they start. Those are the starting or surge watts.
Why add only the largest starting surge?
Motors rarely start at exactly the same moment, so the usual method adds the biggest single surge on top of the total running load. If several motors may start together, enter higher starting watts or a larger margin.
How big a safety margin should I use?
A margin of 10 to 25% is common. Generators run more efficiently and last longer below full load, and it leaves room for items you forget. Many manufacturers recommend not running continuously above about 80-90% of rated output.
Where do I find the wattage of an appliance?
Check the nameplate or manual. If only amps are listed, multiply amps by volts (for example 5 A × 120 V = 600 W). Starting watts are often not listed; motors typically need 2 to 3 times their running watts to start.
What size generator runs a house?
Essentials like a fridge, sump pump, furnace fan, lights and electronics usually fit a 5,000-7,500 W portable generator. Running central air, an electric water heater or an electric range typically needs 15,000-22,000 W or more, often a standby unit installed with a transfer switch by an electrician.
Related tools
Solar Panel CalculatorEstimate solar system size, number of panels and roof area from your monthly kWh and sun hours.Electricity Cost CalculatorEstimate kWh usage and electricity costs.Three-Phase Power CalculatorkW, kVA and kVAR from volts, amps and power factor, or three-phase current from kW or kVA.Battery Life CalculatorEstimate how long a battery lasts from its mAh or Wh and the load.Percentage CalculatorWork out percentages, increases and decreases.Mortgage CalculatorMonthly mortgage payment with taxes, insurance, PMI and HOA, plus a yearly amortization schedule.GST CalculatorAdd or remove GST at any rate, with India CGST/SGST split and AU, NZ and Canada presets.Percentage Change CalculatorPercent increase or decrease between two values, and reverse.Percentage Difference CalculatorFind the percent difference between two values, with the formula.Tip CalculatorWork out the tip and split the bill between any number of people.Discount CalculatorSale price, percent off, stacked discounts and sales tax.Profit Margin CalculatorGross margin, markup, cost or price: solve for any one, single or bulk.Salary to Hourly CalculatorConvert hourly, weekly, monthly and yearly pay, with overtime.Age CalculatorFind your exact age and next birthday countdown.Pregnancy Due Date CalculatorFind your due date and how many weeks pregnant you are.Ovulation CalculatorEstimate ovulation and fertile days for the next 6 months.BMI CalculatorCalculate BMI and a healthy weight range.TDEE Calorie CalculatorFind maintenance calories, calories to lose weight and macros.BMR CalculatorCalculate basal metabolic rate with three formulas and daily calories.Loan CalculatorMonthly payments and amortization for loans and mortgages.Mortgage Refinance CalculatorCompare your current and new mortgage, break-even month and savings.Extra Mortgage Payment CalculatorSee how extra payments cut your mortgage term and interest.Compound Interest CalculatorSee how savings and investments grow over time.Square Footage CalculatorTotal sq ft and m² for rooms of any shape, with cost estimate.One Rep Max CalculatorEstimate your 1RM with Epley and Brzycki, plus a percentage table.Weighted Average CalculatorCalculate a weighted mean from values and weights, step by step.Macro CalculatorDaily protein, carb and fat targets for your calorie goal.Protein Intake CalculatorFind how much protein you need per day and per meal.Ratio CalculatorSimplify, solve and scale ratios with step-by-step working.Proportion CalculatorSolve A/B = C/D for x with cross multiplication steps.Rent vs Buy CalculatorCompare the long-run cost of renting versus buying a home.401(k) CalculatorProject your 401(k) balance with employer match and growth.Scientific CalculatorTrig, logs, powers and more in your browser.Average CalculatorMean, weighted average, median, sum, min and max of any list.Standard Deviation CalculatorStandard deviation, variance, mean, median, mode and quartiles.Receipt MakerFill in a receipt template with items and tax, then print or save PDF.Ohm's Law CalculatorSolve voltage, current, resistance and power from any two values.Resistor Color Code CalculatorRead 4, 5 and 6 band resistor colors, or find colors for a value.Dog Age CalculatorConvert dog years to human years by size.Running Pace CalculatorCalculate pace and predict race times.Cat Age CalculatorConvert cat years to human years.Fuel Cost CalculatorWork out trip fuel costs and split them.Concrete CalculatorEstimate concrete volume, bags and cost.Recipe ScalerScale recipe ingredients to any number of servings.Sleep CalculatorFind the best bedtime or wake-up time using 90-minute sleep cycles.VAT CalculatorAdd or remove VAT and sales tax with country rate presets.Car Loan CalculatorMonthly car payment with down payment, trade-in, APR and amortization.Mortgage Affordability CalculatorHow much house you can afford from income, debts and DTI limits.GPA CalculatorWeighted and unweighted GPA by semester, plus cumulative GPA.Body Fat CalculatorBody fat % with the US Navy and BMI methods, lean vs fat mass.Fraction CalculatorAdd, subtract, multiply and divide fractions with steps.Graphing CalculatorPlot multiple functions with zoom, pan, intersections and a value table.Retirement CalculatorProject retirement savings and see your shortfall or surplus.Savings Goal CalculatorMonthly deposit needed to reach a savings goal by a deadline.Inflation CalculatorValue of a dollar between any two years using US CPI data.Budget CalculatorMonthly budget planner with the 50/30/20 rule and a donut chart.Debt Payoff CalculatorCompare debt snowball vs avalanche: payoff date and interest saved.CAGR CalculatorCompound annual growth rate, or solve for a target end value.Water Intake CalculatorHow much water to drink a day, with an hourly drinking schedule.Paint CalculatorHow much paint for a room, minus doors and windows, in gallons or liters.Tile CalculatorHow many tiles and boxes you need for a floor or wall, with waste.Flooring CalculatorWork out flooring area, boxes needed and cost with waste allowance.Mulch CalculatorFind how much mulch you need in cubic yards and bags.Gas Mileage CalculatorMPG and L/100 km from odometer readings, plus trip cost.Tire Size CalculatorCompare two tire sizes: diameter, difference % and speedometer error.Car Depreciation CalculatorEstimate your car's value over time and its projected resale price.Cooking Time CalculatorRoast and turkey cooking times by meat, weight and oven temperature.Thawing Time CalculatorHow long to thaw a turkey or meat in the fridge or cold water.CTR CalculatorCalculate click-through rate and compare it with industry benchmarks.Conversion Rate CalculatorCalculate e-commerce conversion rate, revenue per visitor and goals.Capacitor Code CalculatorDecode 3-digit capacitor codes to pF, nF and µF, and back.Power Factor CalculatorCalculate power factor, kW, kVA and kVAR, and correction capacitor size.Cups to GramsConvert cups, tablespoons and teaspoons to grams for flour, sugar, butter and more.Baking Conversion CalculatorCups to grams by ingredient, oven temperatures and pan size swaps.EV Charging Cost CalculatorCost to charge an electric car, per charge, per mile and per km.CPM CalculatorSolve CPM, cost, impressions, CTR and CPC for ad campaigns.LED Resistor CalculatorFind the resistor for an LED, with nearest standard value and wattage.Quote Estimate GeneratorCreate a quote or estimate with line items and tax, then save as PDF.Voltage Divider CalculatorVout from R1, R2 and Vin, with loaded and unloaded output.Speed Distance Time CalculatorSolve for speed, distance or travel time and get your arrival time.Horsepower & Torque CalculatorConvert torque and RPM to horsepower and estimate quarter-mile times.Gravel & Crushed Stone CalculatorWork out cubic yards, tons and bags of gravel or crushed stone.Roofing Calculator (Roof Squares)Estimate roof area, squares, shingle bundles and cost from pitch.Pizza Dough Calculator (Baker's Percentage)Work out flour, water, salt and yeast for any number of pizzas.Sourdough & Bread Hydration CalculatorFind true dough hydration with starter, or build a sourdough recipe.A/B Test Significance CalculatorCheck if your A/B test result is statistically significant.ROAS Calculator (Return on Ad Spend)Calculate ROAS, break-even ROAS and profit for each ad channel.Series & Parallel Resistor CalculatorAdd resistors in series or parallel and find standard value combinations.FIRE CalculatorFind your FIRE number, years to financial independence and Coast FIRE target.Ideal Weight CalculatorCompare ideal body weight from the Robinson, Miller, Devine and Hamwi formulas.Square Root CalculatorFind square, cube and nth roots with simplified radical form and steps.Drywall CalculatorCount drywall sheets, screws, joint compound and tape for walls and ceilings.Driving Time CalculatorWork out driving time, breaks, total trip time and arrival time for a road trip.Coffee Ratio CalculatorWork out coffee and water amounts for pour over, French press, espresso and more.Customer Lifetime Value CalculatorCalculate customer lifetime value, LTV:CAC ratio and CAC payback from ARPU and churn.555 Timer CalculatorAstable frequency, duty cycle and monostable pulse width for the NE555 timer.Simple Interest CalculatorCalculate simple interest and final amount, or solve for principal, rate or time.Calorie Deficit CalculatorFind your daily calorie target and deficit to reach a goal weight safely.Exponent CalculatorRaise any number to a power, including negative and fractional exponents.Brick CalculatorEstimate bricks, mortar volume and mortar bags for a wall, minus openings.Jet Lag CalculatorTime difference, recovery days and a day-by-day sleep shift plan for jet lag.Cake Pan Size ConverterConvert a recipe between round, square, rectangle and Bundt pans and scale the batter.Churn Rate CalculatorCalculate customer churn and retention rates and convert monthly churn to annual.Molar Mass CalculatorMolar mass of any chemical formula with an element-by-element mass % breakdown.APR CalculatorFind a loan's true APR including fees, the monthly payment and APR to APY conversions.Weight Loss Percentage CalculatorWork out the percentage of body weight you have lost and track progress to your goal.Logarithm CalculatorCalculate log in any base, ln, log10, log2 and antilog with change-of-base steps.Fence CalculatorWork out fence posts, rails, pickets and concrete bags for any fence length.Road Trip Cost CalculatorEstimate fuel or charging, lodging, food and tolls for a road trip, split per person.Oven Temperature ConverterConvert oven temperatures between °C, °F and gas mark, with fan oven settings.YouTube Money CalculatorEstimate YouTube earnings per day, month and year from views and RPM by niche.Interactive Periodic TableAll 118 elements with colour modes, filters, search and full element details.Multiplication Table GeneratorPrintable multiplication charts up to 30 × 30, single tables and practice sheets.APY CalculatorTurn an interest rate into APY and project savings growth with monthly deposits.Calories Burned CalculatorEstimate calories burned for 100+ activities from MET values, weight and time.Quadratic Equation SolverSolve ax² + bx + c = 0 with exact roots, steps, vertex and a parabola graph.Deck CalculatorDeck boards, joists, posts, screws and total cost from your deck size.Packing List GeneratorBuild a travel packing checklist for your trip type, length and weather.Recipe Calorie CalculatorAdd ingredients or paste a recipe to get calories and macros per serving.Instagram Engagement Rate CalculatorCalculate Instagram engagement rate by followers or reach and compare it to benchmarks.Chemical Equation BalancerBalance chemical, ionic and redox equations with the matrix method and steps.Times Tables PracticeTimed times tables drills with a number pad, streaks and an accuracy heatmap.CD CalculatorFind a CD's maturity value, interest earned, APY vs APR and early-withdrawal penalty.Steps to Calories CalculatorConvert steps to distance and calories burned from your height, weight and pace.System of Equations SolverSolve 2×2 and 3×3 linear systems with exact fractions and Gaussian elimination steps.Wallpaper CalculatorWork out how many rolls of wallpaper you need, with pattern repeat and waste.Travel Budget CalculatorPlan a trip budget by category, travelers and days, with a daily budget per person.Party Food CalculatorWork out how much food, drink and ice per person for any party, with a shopping list.Ecommerce Profit CalculatorNet profit, margin, markup and break-even ROAS per order after fees, ads and returns.Molarity CalculatorSolve mass, volume, molarity or molar mass, and C1V1 = C2V2 dilutions with units.Fraction VisualizerInteractive fraction circles and bars: equivalents, comparing, adding and simplifying.ROI CalculatorWork out ROI and annualized ROI, and compare up to three investments side by side.Heart Rate Zone CalculatorFind max heart rate and 5 training zones with the Fox, Tanaka, Gulati or Karvonen method.Matrix CalculatorAdd, multiply, invert and row-reduce matrices up to 5×5 with exact fractions and steps.Stair CalculatorFind riser height, tread run, stringer length and angle, with IRC code checks.Engine Displacement CalculatorTurn bore, stroke and cylinders into cc, liters and cubic inches, or solve bore or stroke.Wine Pairing GuidePick a dish to see which wines go with it and why, or pick a wine to find foods.Amazon FBA CalculatorEstimate Amazon FBA fees, profit per unit, margin, ROI and break-even price.pH CalculatorConvert pH, pOH, [H+] and [OH-], or find the pH of strong and weak acids and bases.Number Line GeneratorDraw number lines with any range, fractions or decimals, points, jumps and inequalities.Investment Return CalculatorProject investment growth with monthly contributions, nominal vs real after inflation.Waist to Hip Ratio CalculatorWork out your waist-to-hip ratio and WHO health risk category for men and women.Prime Number CheckerCheck if a number is prime, factor it with a factor tree and list primes in a range.Board Foot CalculatorAdd up board feet and lumber cost for any list of boards, nominal or actual size.Gear Ratio CalculatorGear ratio, output rpm and torque for multi-stage gear trains, plus vehicle speed at rpm.Sugar Substitute ConverterSwap sugar for stevia, monk fruit, erythritol, honey and more, with baking adjustments.Etsy Fee CalculatorEtsy listing, transaction, processing and Offsite Ads fees, payout and net profit.Ideal Gas Law CalculatorSolve PV = nRT for pressure, volume, moles or temperature with automatic unit conversion.Teaching ClockInteractive analog clock with draggable hands, time in words and a telling-time quiz.Dividend CalculatorProject dividend income with yield, dividend growth and DRIP reinvestment over time.Lean Body Mass CalculatorEstimate lean body mass, fat mass and body fat % with the Boer, James and Hume formulas.GCF and LCM CalculatorFind the GCF and LCM of two or more numbers with Euclid steps and prime factorization.Insulation CalculatorFind the R-value to add for your climate zone and how many batts or blown-in bags to buy.Boat Fuel CalculatorPlan boat fuel for a trip in nautical miles with the 1/3 reserve rule, range and endurance.Egg Boiling TimerBoiled egg timer by size, start temperature, doneness and altitude, with an alarm.eBay Fee CalculatoreBay final value fee, per-order fee, ad fees, payout and net profit on any sale.Half Life CalculatorSolve radioactive decay for amount left, half-life, time or initial amount, with a curve.Alphabet Tracing WorksheetPrint letter, alphabet, number and name tracing worksheets with dotted letters and guide lines.Stock Profit CalculatorStock trade profit and % return after commissions, plus the break-even sell price.Body Surface Area CalculatorCalculate body surface area in m² with the Du Bois, Mosteller, Haycock and other formulas.Dollar Cost Averaging CalculatorSee units bought, average cost, value and profit for regular buys at your own price list.Conception Date CalculatorEstimate when you conceived from your due date, last period or an ultrasound scan.Significant Figures CalculatorCount sig figs, round to any number of significant figures and do arithmetic with sig fig rules.Soil CalculatorWork out cubic feet, cubic yards and bags of soil for raised beds, round and triangle beds.Startup Runway CalculatorProject cash, burn rate and runway month by month, with growth, break-even and zero-cash date.Kinetic Energy CalculatorSolve KE = ½mv² and PE = mgh for energy, mass, speed or height, with unit conversions.Break Even CalculatorFind break-even units and revenue, contribution margin, margin of safety and a cost-volume chart.Period CalculatorLog period start dates to predict your next 6 periods, ovulation and fertile days.Scientific Notation ConverterConvert numbers to and from scientific, engineering and E-notation, with exact digits and SI prefixes.Grass Seed CalculatorFind how much grass seed you need by lawn area and grass type, for a new lawn or overseeding.SaaS Pricing CalculatorModel flat, per-seat, tiered and volume plans with annual discounts to get MRR, ARR and ARPU.Projectile Motion CalculatorRange, max height, flight time and impact speed of a projectile, with an animated trajectory.Net Worth CalculatorList assets and debts by category to get your net worth, debt ratio, donut charts and history.Pregnancy Weight Gain CalculatorSee your recommended pregnancy weight gain by BMI and week, using the IOM 2009 guidelines.Grade Percentage CalculatorTurn points earned out of total into a percentage and letter grade, with a points-off grid.Rain Gutter CalculatorSize gutters and downspouts from roof area, roof pitch and local rainfall intensity.Employee Cost CalculatorWork out the true cost of an employee: payroll taxes, benefits, overhead and real hourly cost.Free Fall CalculatorFall time and impact velocity from a height, or height from time or speed, with a chart and table.Emergency Fund CalculatorFind how big your emergency fund should be and how long it takes to save it, with interest.Baby Percentile CalculatorWeight, length and head circumference percentiles for babies 0–24 months on WHO growth charts.Final Grade CalculatorFind the score you need on your final exam to reach a target grade, with weighted categories.Cubic Yard CalculatorConvert length, width and depth in any unit to cubic yards, cubic feet, m³ and material weight.Meeting Cost CalculatorWork out what a meeting really costs from attendees and salaries, with a live cost ticker.Velocity CalculatorSolve v = d/t and a = Δv/t for any variable, plus a SUVAT solver for any three kinematics values.Credit Card Interest CalculatorSee how long minimum payments take, the total interest and how much a fixed payment saves.Child Height PredictorEstimate your child's adult height from both parents' heights with the mid-parental method.Grade Curve CalculatorCurve a list of test scores by flat, bell curve, square root or scaling, with stats and CSV export.Moving Cost CalculatorCompare DIY truck, full-service movers and container costs, with truck size and packing estimates.Inventory Turnover CalculatorInventory turnover ratio and days inventory outstanding from COGS or sales and average stock.Torque CalculatorSolve τ = r·F·sin θ for torque, force, lever arm or angle, and convert torque to power at any rpm.Wedding Budget PlannerSplit a wedding budget by category, then track estimated, actual and paid costs with a chart.Life Expectancy CalculatorEstimate remaining life expectancy from age and sex, with rough lifestyle adjustments.Personal Loan CalculatorMonthly payment, total cost and true APR of a personal loan, including the origination fee.Blood Alcohol CalculatorEstimate BAC over time from your drinks with the Widmark formula, with peak and time to sober.Pythagorean Theorem CalculatorSolve for the hypotenuse or a missing leg of a right triangle, with a diagram and steps.Wire Size CalculatorFind the AWG or kcmil wire size for a load from amps, distance, voltage and allowed voltage drop.EOQ CalculatorEconomic order quantity, orders per year, reorder point, safety stock and a total cost curve.Wavelength Frequency CalculatorConvert frequency to wavelength and back for light, radio or sound, with photon energy and band.Amortization CalculatorMonth-by-month loan amortization schedule with yearly totals and an extra payment option.Sales Tax CalculatorAdd sales tax to a price or find the pre-tax price from a total, with US state rates.Markup CalculatorFind the selling price from cost and markup, or the markup and margin from cost and price.Commission CalculatorCalculate flat or tiered sales commission and total pay with a base salary.Overtime CalculatorOvertime pay at time and a half or double time, with weekly, monthly and annual totals.Pay Raise CalculatorNew salary after a raise by percent or amount, with hourly, monthly and real (after inflation) figures.Unit Price CalculatorCompare up to 4 products by price per ounce, pound, liter or item and find the best deal.Split Bill CalculatorSplit a bill with tax and tip equally, by shares, or by what each person ordered.Paycheck CalculatorEstimate take-home pay per paycheck from hourly or salary pay, taxes and deductions.Freelance Hourly Rate CalculatorWork out the hourly and day rate you need from income goals, expenses, taxes and time off.Student Loan CalculatorFind your student loan payment, total interest and how extra payments shorten payoff.Car Lease CalculatorCalculate a monthly car lease payment with depreciation, finance fee, residual and tax.Down Payment CalculatorSee your home down payment, loan, monthly payment, PMI and how long it takes to save.Cap Rate CalculatorCalculate a rental property's NOI, cap rate and optional cash-on-cash return.Rental Yield CalculatorCalculate gross and net rental yield for a buy-to-let or rental property.Debt-to-Income Ratio CalculatorCalculate front-end and back-end debt-to-income ratio and compare with lender limits.Credit Utilization CalculatorCalculate per-card and overall credit utilization and how much to pay to reach 30% or 10%.50/30/20 Budget CalculatorSplit take-home pay into needs, wants and savings with the 50/30/20 rule or your own split.Roth IRA CalculatorProject your Roth IRA balance at retirement with contribution limits, catch-up and growth.Present Value CalculatorFind what a future sum or a series of payments is worth today at a discount rate.Future Value CalculatorCalculate the future value of savings with compounding, regular payments and payment timing.NPV CalculatorCalculate net present value, PV table, profitability index and payback from cash flows.IRR CalculatorFind the internal rate of return of cash flows, with an NPV profile chart and optional MIRR.Rule of 72 CalculatorEstimate how long money takes to double with the rule of 72, 70 and 69.3 vs. the exact answer.Annuity CalculatorCalculate annuity payouts from a lump sum, or how an annuity grows with regular contributions.Savings CalculatorSee how savings grow with an initial deposit, monthly deposits and compound interest.Depreciation CalculatorStraight-line, declining balance, double declining and sum-of-years depreciation schedules.Crypto Profit CalculatorCalculate crypto trade profit, ROI and break-even price after buy and sell fees.PayPal Fee CalculatorWork out PayPal fees, what you receive, and how much to ask for to get an exact amount.Stripe Fee CalculatorCalculate Stripe fees and payouts, or how much to charge to receive an exact amount.Net Promoter Score CalculatorCalculate NPS from promoter, passive and detractor counts or pasted 0–10 survey scores.CPC CalculatorCalculate cost per click from ad spend and clicks, plus CPM, CTR, CPA and ROAS.TikTok Money CalculatorEstimate TikTok sponsored post rates and Creator Rewards earnings from your views.Pregnancy Week CalculatorFind how many weeks pregnant you are from your last period, due date or conception.A1C CalculatorConvert A1C % to estimated average glucose in mg/dL and mmol/L, and back.Keto Macro CalculatorGet daily calories and keto fat, protein and net carb grams for your goal.VO2 Max CalculatorEstimate VO2 max from a Cooper run, resting heart rate or 1.5-mile time, with norms.FFMI CalculatorFind your fat-free mass index and normalized FFMI from weight, height and body fat.Caffeine CalculatorAdd up daily caffeine, compare it with 400 mg and see how much is left at bedtime.Puppy Weight CalculatorEstimate your puppy's adult weight from its age, current weight and breed size.Dog Food CalculatorFind your dog's daily calories and cups of food from weight and life stage.Dog Pregnancy CalculatorFind your dog's due date from the mating date, with a week-by-week pregnancy calendar.CGPA to Percentage CalculatorConvert CGPA to percentage (CBSE × 9.5, 10-point, 4-point) and back.Attendance CalculatorSee your attendance %, classes needed to reach 75% or how many you can skip.Golf Handicap CalculatorCalculate your WHS Handicap Index and Course Handicap from scores, rating and slope.Area CalculatorFind the area of squares, rectangles, triangles, circles, trapezoids, ellipses and sectors.Volume CalculatorVolume of a cube, box, cylinder, sphere, cone, pyramid or capsule, in liters and gallons too.Surface Area CalculatorSurface area of a cube, box, cylinder, sphere, cone or pyramid, with lateral and base areas.Circle CalculatorEnter a circle's radius, diameter, circumference or area and get all the others.Triangle CalculatorSolve any triangle from SSS, SAS, ASA, AAS or right-triangle values: sides, angles, area, type.Slope CalculatorSlope, angle, line equation y = mx + b and distance from two points, with a graph.Midpoint CalculatorFind the midpoint of two points in 2D or 3D, or the missing endpoint from a midpoint.Distance Formula CalculatorDistance between two points in 2D or 3D with step-by-step work and an exact radical answer.Percent Error CalculatorPercent error between experimental and theoretical values, for one result or several trials.Z-Score CalculatorZ-score from a value, mean and SD, plus percentile and p-value; or the value from z.Probability CalculatorFind and, or, not, conditional and at-least-once probabilities from P(A) and P(B).Permutation and Combination CalculatorCalculate nPr and nCr, with or without repetition, as exact big numbers.Factorial CalculatorExact n! up to 5000! with digit count, trailing zeros and double factorial.Mean Median Mode CalculatorFind the mean, median, mode, range, min, max, sum and count of a list of numbers.Rounding CalculatorRound to decimal places, significant figures or the nearest 10, 100 or 0.5, any rule.Long Division CalculatorDivide with quotient, remainder, decimals and a step-by-step long division layout.Prime Factorization CalculatorFind prime factors in exponent form with a factor tree, divisor count and divisors list.Modulo CalculatorCalculate a mod n and the quotient, with floored, truncated and Euclidean rules.Cube Root CalculatorFind cube roots and nth roots, check perfect cubes and simplify radicals.Exponential Growth CalculatorExponential growth and decay: final amount, rate or time, discrete or continuous.Confidence Interval CalculatorConfidence interval and margin of error for a mean or a proportion, with steps.Sample Size CalculatorHow many survey responses you need for a given confidence level and margin of error.Percentile CalculatorValue at any percentile, percentile rank of a score, quartiles, IQR and outliers.Linear Regression CalculatorLeast-squares line of best fit: slope, intercept, r, r², predictions and a scatter plot.Correlation Coefficient CalculatorPearson r and Spearman rank correlation with significance and interpretation.System of Equations SolverSolve 2×2, 3×3 and 4×4 linear systems with exact fractions and step-by-step working.Acceleration CalculatorAcceleration from velocity change and time, distance and time, or force and mass.Force CalculatorSolve F = ma for force, mass or acceleration, plus weight on every planet.Density CalculatorSolve density, mass or volume with unit conversion and a table of common material densities.Momentum CalculatorCalculate momentum (p = mv), mass, velocity, impulse and momentum change with unit conversion.Potential Energy CalculatorGravitational PE = mgh and spring PE = ½kx²: solve for energy, mass, height, k or stretch.Power CalculatorCalculate power from work and time, force and velocity, or volts and amps, in W, kW and hp.Dilution CalculatorSolve C1V1 = C2V2 for any variable: stock volume, final volume or concentration, with units.BTU CalculatorEstimate air conditioner BTU, tons and heating BTU for a room from its size and conditions.Pool Volume CalculatorFind pool volume in gallons and liters for rectangular, round, oval and kidney pools.Paver CalculatorCount pavers for a patio or path, with joints and waste, plus gravel base and sand volumes.Concrete Block CalculatorCount concrete blocks (CMU) for a wall, minus doors and windows, plus mortar bags.Roof Pitch CalculatorConvert rise and run or an angle to roof pitch x/12, degrees, slope % and rafter multiplier.Voltage Drop CalculatorVoltage drop in volts and percent for copper or aluminum wire, AWG or mm², 1- or 3-phase.2-Stroke Oil Mix CalculatorHow much 2-stroke oil to add to gas for 50:1, 40:1, 32:1 and more, in fl oz or ml.Carbon Footprint CalculatorEstimate your yearly CO2e from driving, flights, electricity, gas and diet in tonnes.TV Size CalculatorFind a TV or monitor's width, height and area from its diagonal and compare two screens.TV Viewing Distance CalculatorBest seating distance for your TV size and resolution (SMPTE, THX, 4K), or the best TV size.PPI CalculatorPixel density (PPI), dot pitch and retina viewing distance from resolution and screen size.Download Time CalculatorHow long a file takes to download at your internet speed, or the speed you need.Online CalculatorFree basic and scientific calculator with keyboard support, memory keys and a history tape.Math Worksheet GeneratorCreate printable addition, subtraction, multiplication and division worksheets with answer keys.HELOC CalculatorAvailable home equity credit line plus interest-only and repayment-period HELOC payments.Mortgage Payoff CalculatorNew payoff date, time saved and interest saved with extra or lump-sum mortgage payments.Biweekly Mortgage CalculatorCompare monthly and biweekly mortgage payments: interest saved, years saved and payoff date.Mortgage Points CalculatorIs buying discount points worth it? Cost, monthly savings, break-even month and net savings.Closing Cost CalculatorEstimate itemized closing costs, prepaids and total cash to close for a home purchase.Property Tax CalculatorAnnual and monthly property tax from value, assessment ratio, exemptions and % or mill rate.Rent Affordability CalculatorHow much rent you can afford with the 30% rule, the 40x income rule and your debts.Loan Comparison CalculatorCompare up to three loans: monthly payment, total interest, fees, total cost and APR.Balloon Payment CalculatorMonthly payment and lump-sum balloon due on an amortizing or interest-only loan.Business Loan CalculatorBusiness loan payments (monthly, weekly or daily), total cost and effective APR with fees.Interest Rate CalculatorSolve a loan's interest rate (APR) from the amount, payment and term using Newton's method.Loan-to-Value CalculatorLTV, CLTV and HCLTV ratios, home equity, and the pay-down needed to drop PMI.Yield to Maturity CalculatorFind a bond's yield to maturity, current yield and yield to call from its price and coupon.Bond Price CalculatorPrice a bond from its coupon, yield and term, with premium or discount and a cash flow table.Stock Average CalculatorAverage cost of several stock buys, plus how many shares to buy to reach a target average.Position Size CalculatorHow many shares or units to trade so a stop-loss risks only a set share of your account.P/E Ratio CalculatorPrice-to-earnings ratio, earnings yield and PEG ratio from share price, EPS and growth.EPS CalculatorBasic and diluted earnings per share from net income, preferred dividends and share count.WACC CalculatorWeighted average cost of capital from equity, debt, their costs and the tax rate.CAPM CalculatorExpected return from the risk-free rate, beta and market return using the CAPM formula.Payback Period CalculatorPayback and discounted payback period for an investment with even or uneven cash flows.Effective Annual Rate CalculatorConvert a nominal rate to the effective annual rate (EAR / APY) for any compounding, or back.Dividend Reinvestment CalculatorProject a DRIP: portfolio value, shares and income with and without reinvesting dividends.Credit Card Payoff CalculatorSee when your card is paid off, the interest you pay, and how it compares with the minimum.Debt Snowball CalculatorPlan payoff of several debts: snowball vs. avalanche order, debt-free date and interest saved.College Savings CalculatorProject future college costs and see how much you need to save each month to pay for them.Retirement Withdrawal CalculatorSee how many years your retirement savings last with withdrawals, returns and inflation.Hourly to Salary CalculatorConvert an hourly wage to annual, monthly, biweekly, weekly and daily pay, with overtime.Bonus Tax CalculatorEstimate take-home pay on a bonus: 22% federal supplemental rate, FICA and state tax.Self-Employment Tax CalculatorCalculate Social Security and Medicare self-employment tax (15.3%) and the deductible half.Price per Square Foot CalculatorFind price per sq ft or m², total price or area, and compare several homes by value.Real Estate Commission CalculatorCalculate realtor commission, the agent and broker split, and the seller's net proceeds.Rent Split CalculatorSplit rent fairly between up to 6 roommates by room size, income or equally.Car Affordability CalculatorSee how much car you can afford with the 20/4/10 rule or your monthly budget.Daily Interest CalculatorInterest per day and total interest for any number of days, simple or compounded daily.Contribution Margin CalculatorContribution margin per unit, CM ratio, operating profit and break-even point.Customer Acquisition Cost CalculatorCAC from marketing and sales spend, plus LTV:CAC ratio and payback months.CPA CalculatorCost per acquisition from ad spend, plus break-even and target CPA from your margin.Average Order Value CalculatorAverage order value from revenue and orders, plus the revenue impact of raising AOV.Reorder Point CalculatorReorder point from daily demand, lead time and safety stock, with days until the next order.Safety Stock CalculatorSafety stock by days of cover, max − average, or service level (Z × σ × √lead time).Dimensional Weight CalculatorDIM weight and billable weight for a box in inches or cm with 139, 166, 5000 or 6000 divisors.Food Cost CalculatorPlate cost per portion, food cost percentage and menu price for any recipe.Growth Rate CalculatorTotal growth, compound growth rate per period, linear average and a projection.RPM CalculatorRevenue per 1,000 views from earnings, estimated earnings from RPM, and views for a goal.Customer Retention Rate CalculatorCustomer retention rate and churn from start, end and new customer counts.Margin to Markup CalculatorConvert gross margin % to markup % and back, with price multiplier and conversion table.Army Body Fat CalculatorArmy tape test body fat (2023 one-site or legacy method) vs AR 600-9 standards by age.Steps to Miles CalculatorConvert steps to miles and km from your height or step length, with time and calories.Swimming Pace CalculatorSwim pace per 100 m or yd, speed and splits from distance and time, plus CSS from a test.Blood Pressure CalculatorBlood pressure reading to AHA category, mean arterial pressure and pulse pressure.Waist to Height Ratio CalculatorWaist to height ratio in cm or inches with health bands and the 0.5 rule waist target.Fiber Intake CalculatorDaily fiber target from age, sex and calories (14 g per 1,000 kcal and IOM table).Alcohol Units CalculatorUK alcohol units from volume and ABV, plus a weekly total vs the 14-unit guideline.hCG Doubling Time CalculatorTwo hCG results and hours apart to doubling time and the equivalent 48-hour rise.IVF Due Date CalculatorIVF due date from a day 3, 5 or 6 embryo transfer or egg retrieval, with weeks pregnant.Baby Formula CalculatorEstimate daily and per-feed baby formula in ml and oz from weight, age and feeds.Barbell Plate CalculatorWhich plates to load on each side of the bar for any target weight, in kg or lb.Wilks CalculatorPowerlifting Wilks 2020 and DOTS scores from body weight, sex and total in kg or lb.GFR CalculatorEstimate eGFR from creatinine, age and sex with CKD-EPI 2021 and see the CKD stage.Mean Arterial Pressure CalculatorCalculate mean arterial pressure (MAP) and pulse pressure from a blood pressure reading.Cat Food CalculatorHow much wet and dry food to feed your cat per day, from weight, life stage and activity.Cat Pregnancy CalculatorFind your cat’s due date from the mating date, with a week-by-week pregnancy calendar.Sleep Debt CalculatorFind your weekly sleep debt from hours slept per night and get a simple recovery plan.Screen Time CalculatorSee your daily screen time per year and over your lifetime, and what else you could do.Book Reading Time CalculatorHow long a book takes to read from its pages or words and your reading speed.Pages per Day CalculatorHow many pages to read each day to finish a book by your date, with a reading schedule.Zakat CalculatorCalculate 2.5% zakat on cash, gold, silver and investments against the gold or silver nisab.House Flipping CalculatorFix-and-flip profit, ROI and 70% rule max offer from purchase, rehab, holding and sale costs.Airbnb Income CalculatorShort-term rental net income from nightly rate, occupancy, cleaning, fees and expenses.EV vs Gas Car Cost CalculatorCompare yearly EV charging vs gas fuel costs, cost per mile, savings and CO₂ emissions.Simplify Fractions CalculatorReduce any fraction to lowest terms with GCD steps, mixed number, decimal and equivalents.Cubic Equation SolverSolve ax³ + bx² + cx + d = 0 for real and complex roots with steps and a graph.Vector Calculator2D and 3D vectors: add, subtract, dot and cross product, magnitude, angle, unit vector, projection.Complex Number CalculatorAdd, subtract, multiply, divide complex numbers; polar form, modulus, argument, powers and roots.Summation CalculatorEvaluate sigma notation: sum any expression in n from a to b with partial sums and a chart.Arithmetic Sequence CalculatorFind the n-th term, sum and full list of an arithmetic sequence, or d from two terms.Geometric Sequence CalculatorFind the n-th term, sum and infinite sum of a geometric sequence, or r from two terms.Fibonacci CalculatorExact n-th Fibonacci number (BigInt), sequence lists, Fibonacci check and golden ratio.Pascal's Triangle GeneratorGenerate Pascal's triangle up to row 30, highlight a row and expand (ax + by)ⁿ.Binomial Distribution CalculatorBinomial probabilities P(X = k), at most, at least or between, with mean, variance and chart.Normal Distribution CalculatorNormal probabilities P(X < x), between two values and inverse percentiles, on a shaded bell curve.Poisson Distribution CalculatorPoisson probabilities for a rate λ: exactly k, at most, at least or between, with a chart.T-Test CalculatorOne-sample, two-sample (Welch/pooled) and paired t-tests with p-value and CI.Chi-Square CalculatorChi-square goodness-of-fit and independence tests with p-value and expected counts.P-Value CalculatorOne- or two-tailed p-values from z, t, chi-square or F statistics, with critical values.Variance CalculatorSample and population variance and standard deviation with a step-by-step deviations table.Five Number Summary CalculatorMin, Q1, median, Q3, max, IQR and fences of a data set, with a box plot.Outlier CalculatorFind outliers with 1.5×/3× IQR fences, z-scores or modified z-scores; get the cleaned data.Geometric Mean CalculatorGeometric, harmonic, arithmetic and quadratic means compared, or average growth from % changes.Expected Value CalculatorExpected value, variance and standard deviation from outcomes and their probabilities.Trigonometry CalculatorSin, cos, tan, csc, sec, cot and inverses in degrees or radians, with exact values.Arc Length CalculatorArc length, sector area and chord from radius and angle, or solve for the radius or angle.Cylinder Volume CalculatorCylinder volume in liters, gallons and cubic units from radius or diameter, plus surface area.Regular Polygon CalculatorArea, perimeter, apothem, radius and angles of a regular polygon from any one measurement.Golden Ratio CalculatorSplit a length into golden sections, find a from b, and get a φ scale of design sizes.Factors CalculatorAll factors and factor pairs of a number, prime factors, divisor count and perfect check.Big Number CalculatorExact + − × ÷ mod and powers for huge integers with hundreds of digits, plus digit count.RC Time Constant Calculatorτ = RC, charge % at 1-5τ, and capacitor charge or discharge voltage at any time t.Resonant Frequency CalculatorLC resonant frequency f = 1/(2π√LC), or solve the inductance or capacitance you need.Capacitor Series and Parallel CalculatorTotal capacitance of capacitors in series or parallel, plus stored energy ½CV² and charge.Pressure CalculatorSolve P = F/A for pressure, force or area in Pa, kPa, bar, psi and atm.Work CalculatorSolve W = F·d·cos θ for work, force, distance or angle in J, kWh and ft-lb.Hooke's Law CalculatorSolve F = kx for spring force, spring constant or extension, plus stored spring energy.Centripetal Force CalculatorCentripetal force and acceleration from mass, radius and speed or RPM: F = mv²/r.Gravitational Force CalculatorNewton's law of gravitation F = Gm₁m₂/r² for any two masses, with planet presets.Speed of Sound CalculatorSpeed of sound from air temperature or medium, and distance from an echo or thunder delay.Doppler Effect CalculatorObserved frequency from source and observer speeds, or source speed from a pitch shift.Specific Heat CalculatorSolve Q = mcΔT for heat energy, mass, specific heat or temperature change, with materials.Percent Yield CalculatorPercent yield from actual and theoretical yield, or theoretical yield from moles and formulas.PPM CalculatorConvert ppm to mg/L, %, ppb and mg/kg, find ppm of a solution, or ppm to mg/m³ for gases.Grams to Moles CalculatorConvert grams to moles and back from a chemical formula, with molar mass and atom counts.Decibel CalculatorAdd dB levels, convert power or voltage ratios to dB, and find sound level at a distance.Pipe Flow Rate CalculatorFlow rate from pipe diameter and velocity (GPM, L/s, m³/h), velocity from flow, or pipe size.Stud CalculatorCount wall studs and plates from wall length, spacing, corners and openings.Carpet CalculatorCarpet for your rooms in sq ft and sq yd from a 12 or 15 ft roll, with padding and cost.Baseboard CalculatorLinear feet of baseboard and number of pieces for your rooms, minus doorways.Grout CalculatorGrout in kg, lb and bags from tile size, joint width, depth and area.Rebar CalculatorRebar for a slab grid: bars each way, total length, weight by bar size and stock bars.Asphalt CalculatorTons of asphalt from area and thickness at 145 lb/ft³, with volume and cost.Sand CalculatorSand in cubic yards, m³, tons and bags for any area and depth.Retaining Wall CalculatorBlocks, caps, base gravel and drainage stone for a block retaining wall.Siding CalculatorSiding squares, panels and J-channel from walls and gables minus doors and windows.Pool Chlorine CalculatorHow much liquid chlorine, bleach or shock to add to reach a target free chlorine.Aquarium Volume CalculatorFish tank gallons, liters and water weight: rectangle, cylinder, bow-front and hexagon tanks.Fertilizer CalculatorPounds of fertilizer and bags for your lawn from N-P-K and a target rate per 1,000 sq ft.Raised Bed Soil CalculatorSoil for raised garden beds in cubic feet, cubic yards, liters and bags, with mix recipes.Plant Spacing CalculatorHow many plants fit an area at a given spacing, in a square, triangular or row pattern.LED Savings CalculatorYearly savings, kWh saved and payback time when switching old bulbs to LED.Tank Volume CalculatorTotal and filled volume of cylinder, rectangular and capsule tanks in gallons and liters.Rainwater Harvesting CalculatorGallons or liters of rainwater a roof collects from its area, rainfall and surface.Quarter Mile CalculatorEstimate 1/4 mile ET and trap speed from horsepower and weight, or HP from a time slip.Compression Ratio CalculatorStatic engine compression ratio from bore, stroke, chamber, gasket, deck and piston volume.Concrete Steps CalculatorConcrete volume and bags for poured steps from step count, rise, run, width and landing.Weighted Grade CalculatorCurrent class grade from weighted categories, plus the score you need on the final.SGPA to CGPA CalculatorCGPA from semester SGPAs and credits, with percentage by ×9.5, ×10 or VTU formula.GPA to Percentage CalculatorConvert a 4.0, 5.0 or 10-point GPA to a percentage and back with common formulas.Meat per Person CalculatorHow much raw meat to buy for a party or BBQ from guests, meat type and appetite.Rice to Water Ratio CalculatorExact water and cook time for any rice in cups or grams: stovetop, rice cooker or Instant Pot.Yeast ConverterConvert fresh, active dry, instant yeast and sourdough starter by grams, teaspoons or packets.Butter ConverterConvert butter between sticks, cups, tablespoons, grams, ounces and 250 g EU blocks.Cake Servings CalculatorHow many wedding or party slices a round, square or sheet cake serves, tier by tier.Fabric Yardage CalculatorHow many yards or meters of fabric to buy for your pieces, width, seams and pattern repeat.Depth of Field CalculatorNear and far focus limits, depth of field and hyperfocal distance for any camera or lens.Crop Factor CalculatorCrop factor, full-frame equivalent focal length and aperture, and field of view for any sensor.Print Size CalculatorPrint size from pixels and DPI, max print size by megapixels, and pixels needed for any print.3D Printing Cost CalculatorCost and selling price of a 3D print: filament, power, machine wear, failures and labor.