Electrical load calculator
A house's calculated load starts with 3 VA per square foot, 1,500 VA for each kitchen and laundry circuit and the nameplate of every fixed appliance, then takes the first 10 kVA in full and 40% of the rest, plus heating or cooling.
0 if you have none
0 if you have none
0 if you have none
0 if you have none
Nameplate watts (amps × 240 V), counted at 100%; 0 if none
Hot tub, well pump: nameplate watts added together
A 125 amp service covers this load. Only the loads entered are counted.
- Calculated load
- 25.2 kVA
- General load after demand factors
- 20,016 VA
- Heating or cooling
- 5,220 VA
How it is calculated
- General: 3 VA × 2,000 sq ft + 3 × 1,500 VA kitchen and laundry circuits + appliances = 35,040 VA
- First 10,000 VA at 100%, the rest at 40% = 20,016 VA
- Larger of heating and cooling: 5,220 VA
- (20,016 + 5,220) ÷ 240 V = 105.2 A
How to calculate a house electrical load
The optional method for a single dwelling adds the general loads, counts the part above 10,000 VA at a reduced share because not everything runs at once, then adds the larger of heating and cooling and any EV charger in full. The worked numbers use the calculator's defaults: 2,000 sq ft, electric range 12,000 W, electric dryer 5,600 W, water heater 5,500 W and dishwasher 1,440 W, an air conditioner of 5,220 W and no electric heat.
Step 1: general load
General load = 3 VA × floor area in sq ft + 1,500 VA × kitchen and laundry circuits (at least 2 + 1) + nameplate of every fixed appliance
Example 3 × 2,000 + 1,500 × 3 + (12,000 + 5,600 + 5,500 + 1,440) = 35,040 VA
Step 2: demand factor
General load after demand = first 10,000 VA in full + 40% of the rest
Example 10,000 + 0.4 × (35,040 − 10,000) = 20,016 VA
Step 3: heating or cooling
Add the larger of: air conditioning or heat pump at 100% of the nameplate, or electric heat at 65% (40% for four or more separately controlled heaters)
Example Air conditioner 5,220 VA, no electric heat: 5,220 VA
Step 4: EV charger
EV charger load = charger nameplate (amps × volts) at 100%, on its own line: no 40% demand factor
Example A 40 A charger at 240 V: 40 × 240 = 9,600 VA, all of it added. The defaults have no charger; with this one the total is 34,836 VA, or 145.2 A, a 150 amp service.
Documents differ here. An EC&M worked example based on the 2020 NEC put a 40 A charger in the general load, where only 40% of it counted above 10,000 VA (3,840 VA). The City of Sacramento worksheet for this method lists the charger on its own line after the 40% step, and the 2026 NEC adds a rule that counts it at 100% with no demand factor. This calculator follows the separate line: the larger, safer number. A load management system can let a charger count less; that is a design for the electrician and the inspector.
Step 5: amps and service size
Amps = (general load after demand + heating or cooling + EV charger) ÷ 240 V
Example (20,016 + 5,220) VA ÷ 240 V = 105.2 A, so a 125 amp service covers the load
House electrical load by square footage
With the calculator's default appliances and air conditioner, a 2,000 sq ft house calculates to 105 A at 240 V and a 4,000 sq ft house to 115 A. The table keeps those appliances and changes only the floor area; enter your own nameplate watts in the calculator above.
| Floor area, sq ft | Calculated load, kVA | Amps at 240 V | Service that covers it |
|---|---|---|---|
| 1,000 | 24 | 100 | 125 A |
| 1,500 | 24.6 | 103 | 125 A |
| 2,000 | 25.2 | 105 | 125 A |
| 2,500 | 25.8 | 108 | 125 A |
| 3,000 | 26.4 | 110 | 125 A |
| 3,500 | 27 | 113 | 125 A |
| 4,000 | 27.6 | 115 | 125 A |
Limits of this estimate
Use the nameplate of your own appliances where you can. A permit application needs the full calculation for your house, done or checked by an electrician, and local rules may require the standard method instead.