Home › Calculators › Electrical & Electronics Calculators
Electrical & Electronics Calculators
Ohm's law, voltage drop, wire size, resistor, capacitor, battery and circuit calculators. 51 free tools that run in your browser, no sign-up needed.
Search results
No tools match your search.
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.Electricity Cost CalculatorEstimate kWh usage and electricity costs.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.EV Charging Cost CalculatorCost to charge an electric car, per charge, per mile and per km.LED Resistor CalculatorFind the resistor for an LED, with nearest standard value and wattage.Voltage Divider CalculatorVout from R1, R2 and Vin, with loaded and unloaded output.Battery Life CalculatorEstimate how long a battery lasts from its mAh or Wh and the load.Series & Parallel Resistor CalculatorAdd resistors in series or parallel and find standard value combinations.555 Timer CalculatorAstable frequency, duty cycle and monostable pulse width for the NE555 timer.Wire Size CalculatorFind the AWG or kcmil wire size for a load from amps, distance, voltage and allowed voltage drop.Solar Panel CalculatorEstimate solar system size, number of panels and roof area from your monthly kWh and sun hours.Voltage Drop CalculatorVoltage drop in volts and percent for copper or aluminum wire, AWG or mm², 1- or 3-phase.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.Generator Size CalculatorAdd appliance running and starting watts to find the generator size you need.LED Savings CalculatorYearly savings, kWh saved and payback time when switching old bulbs to LED.Battery Bank Size CalculatorSize a solar or off-grid battery bank: Ah, kWh and battery count from daily Wh and autonomy.Battery Charge Time CalculatorHow long to charge a battery: mAh or Ah, charger current, efficiency and current charge %.Circuit Breaker Size CalculatorBreaker size from watts or amps, voltage and the 125% continuous rule, with a wire gauge.Conduit Fill CalculatorCheck conduit fill % against the NEC 40% limit for EMT, PVC, RMC and more, with pass/fail.Home Electrical Load CalculatorHome service load in VA and amps with NEC demand factors and a 100/150/200 A recommendation.EV Charging Time CalculatorHow long to charge an EV: battery kWh, charge levels and charger kW, with Level 1/2/DC presets.RLC Impedance CalculatorSeries or parallel RLC impedance, phase angle, resonant frequency and Q at any frequency.Inverter Size CalculatorFind the inverter size for your appliances: continuous watts, surge and battery current.ND Filter CalculatorLong exposure shutter speed for any ND filter in stops, ND number or density.Op Amp Gain CalculatorInverting, non-inverting or differential op amp gain in V/V and dB, with output voltage.PCB Trace Width CalculatorMinimum PCB trace width for a current per IPC-2221, for internal and external layers.RC Filter Cutoff CalculatorRC low-pass or high-pass cutoff frequency, solve R or C, with a Bode magnitude chart.Reactance CalculatorInductive and capacitive reactance at any frequency, or solve for L, C or frequency.SMD Resistor Code CalculatorDecode 3-digit, 4-digit and EIA-96 SMD resistor codes, or find the code for a value.Solar Panel Tilt Angle CalculatorBest fixed tilt, seasonal and monthly solar panel angles and direction for any latitude.Transformer Turns Ratio CalculatorSolve transformer voltage, turns or turns ratio, with primary/secondary current and VA.UPS Runtime CalculatorEstimate UPS battery backup time from battery V, Ah, count, efficiency and load, with Peukert.PC Power Supply CalculatorEstimate your PC's load watts and the PSU wattage you need, with efficiency running costs.Power to Weight Ratio CalculatorVehicle hp per tonne, lb per hp and kW/kg from power and weight; compare cars and bikes.Solar Charge Controller Size CalculatorSize an MPPT or PWM charge controller in amps from panel watts, Voc, Isc and battery voltage.4-20mA CalculatorScale a 4-20 mA signal to a process value and back, with percent and shunt voltage.Antenna Length CalculatorDipole, quarter-wave and 5/8-wave antenna lengths for any frequency or radio band.Battery Pack Calculator18650, 21700 or LiFePO4 series/parallel pack: voltage, Ah, Wh, max current and weight.DC Circuit SimulatorDraw batteries, resistors, bulbs and switches and see voltages and currents flow live.E-Bike Range CalculatorEstimate e-bike miles or km per charge from battery Wh, assist level, weight, speed and hills.Lewis Structure GeneratorDraw Lewis dot structures with valence electrons, lone pairs, formal charges and VSEPR shape.LM317 CalculatorLM317 output voltage from R1 and R2, standard resistors for a target voltage, current limiter.Motor Full Load Current CalculatorFull load amps from motor hp or kW, voltage, phase, efficiency and power factor, with NEC values.Population Growth CalculatorExponential or logistic population growth over time with carrying capacity, table and chart.Rocket Launch ScheduleUpcoming orbital rocket launches with live countdowns, launch windows, pads and filters.Transformer Sizing CalculatorTransformer kVA needed from volts and amps or kW and PF, next standard size and full-load amps.Wire Resistance CalculatorWire resistance from material, AWG or diameter, length and temperature, plus voltage drop.
About Electrical & Electronics Calculators
Electronics calculators for Ohm's law, resistor and capacitor codes, voltage drop, wire size, battery life and power use. Hobbyists and electricians use them to check values before building or wiring a circuit.
Most used here: Ohm's Law Calculator, Resistor Color Code Calculator and Electricity Cost Calculator.