Home Electrical Load Calculator
Estimate the electrical service a house needs. Enter the floor area, cooking and laundry appliances, water heater, HVAC equipment and any EV charger. The calculator applies the dwelling demand factors of the NEC standard method (Article 220, Part III) and the optional method (220.82), then suggests a 100, 125, 150, 200 A or larger service.
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Kitchen/dining 20 A circuits, minimum 2.
Well pump, attic fan, hot tub, etc.
≈ 240 V × the unit's rated load amps or MCA.
Furnace strips, baseboard or heat pump backup heat.
Counted at the larger of 7.2 kW or nameplate.
How to use the Home Electrical Load Calculator
- Enter the living area in square feet (heated floor area, not garage or unfinished spaces).
- Enter the kitchen small-appliance circuits (at least 2) and whether there is a laundry circuit.
- Enter nameplate ratings of electric cooking, dryer, water heater and other fixed appliances. Use 0 for gas appliances.
- Enter the air conditioner or heat pump and electric heat loads, plus any EV charger.
- Read the calculated load and amps and the recommended service size, and use the breakdown to see what drives it.
How the standard method works
The NEC dwelling-unit calculation (Article 220, Part III) adds each type of load with its own demand factor, because not everything runs at full power at the same time:
| Load | How it is counted | NEC reference |
|---|---|---|
| General lighting & receptacles | 3 VA per sq ft of living area | 220.12 / Table 220.12 (220.41 in 2023) |
| Small-appliance circuits | 1,500 VA each (at least 2) | 220.52(A) |
| Laundry circuit | 1,500 VA | 220.52(B) |
| Demand on the three above | First 3,000 VA at 100%, 3,001–120,000 at 35%, rest at 25% | Table 220.42 (220.45 in 2023) |
| Fastened-in-place appliances | 75% of nameplate if 4 or more, otherwise 100% | 220.53 |
| Clothes dryer | Larger of 5,000 VA or nameplate | 220.54 |
| Range (one) | 8 kW up to 12 kW rating, +5% per kW over 12 | Table 220.55, Col. C |
| Heating vs air conditioning | Only the larger of the two | 220.60 |
| EV charging equipment | Larger of 7,200 VA or nameplate | 220.57 |
Service amps = total VA ÷ 240 V, then round up to a standard service size (100, 125, 150, 200 A …).
Example: a 2,000 sq ft home: 6,000 + 3,000 + 1,500 = 10,500 VA → 3,000 + 7,500 × 35% = 5,625 VA. Water heater, dishwasher, disposal and microwave (8,100 VA × 75%) = 6,075 VA; dryer 5,000 VA; 12 kW range 8,000 VA; 5,000 VA air conditioner. Total 29,700 VA ÷ 240 = 123.8 A, so a 125 A service is the minimum and 150 A or 200 A leaves room for growth.
Optional method (220.82)
For a dwelling served by a 120/240 V service of 100 A or more, you may instead add all general loads and appliance nameplates, take the first 10 kVA at 100% and the remainder at 40%, then add the largest heating or cooling load (air conditioning and heat pump compressors at 100%, supplemental and central electric heat at 65%). This method usually gives a lower result for well-equipped homes. Both are shown so you can compare.
Typical appliance ratings
| Appliance | Typical rating |
|---|---|
| Electric range | 8–14 kW |
| Electric dryer | 4.5–5.5 kW |
| Tank water heater | 3.8–5.5 kW |
| Dishwasher | 1,000–1,500 VA |
| Central AC, 3 ton | ~3,500–5,500 VA |
| Level 2 EV charger (32 A / 48 A) | 7.7 kW / 11.5 kW |
Frequently asked questions
How do you calculate the electrical load of a house?
Under the NEC standard method you add the general lighting load (3 VA per square foot), 1,500 VA for each small-appliance circuit and the laundry circuit, apply demand factors (first 3,000 VA at 100%, the next 117,000 VA at 35%, the rest at 25%), then add fixed appliances (75% if there are four or more), the dryer, the range from Table 220.55, the larger of heating or cooling, and EV chargers. Divide the total VA by 240 V to get the service amps.
Is 100 amp service enough?
It can be for a smaller home with gas heat, gas cooking and gas water heating. Homes with electric heat, an electric range and dryer, central air or an EV charger usually calculate to more than 100 A and need 150 A or 200 A. 100 A is the minimum service size for a single-family dwelling under the NEC.
What is the difference between the standard and optional methods?
The standard method (NEC 220 Part III) applies separate demand factors to each type of load. The optional method (220.82) adds all general loads and appliances at nameplate, counts the first 10 kVA at 100% and the rest at 40%, then adds heating or air conditioning. For typical homes with a 120/240 V service of 100 A or more, the optional method often gives a smaller result.
How is an electric range calculated?
For one household range, NEC Table 220.55 Column C allows 8 kW for a range rated up to 12 kW. For each kW (or major fraction of a kW) above 12, the 8 kW is increased by 5%. A 14 kW range is counted as 8 × 1.10 = 8.8 kW. Cooktops and ovens rated 8.75 kW or less can be taken at 80% of nameplate.
Can I add an EV charger to my panel?
Do a load calculation including the charger at the larger of 7,200 VA or its nameplate rating. If the total stays within the service rating you may have room; if not, options include a service upgrade, a smaller charging current, or an energy management system that limits charging when other loads are high.
Does this replace an electrician's calculation?
No. This is an estimate for planning. Local codes, the NEC edition your jurisdiction uses, utility rules and actual equipment ratings decide the final service size, so have a licensed electrician perform the official load calculation and permit work.
Is my data uploaded?
No. The calculator runs entirely in your browser.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.