Calculators · Electrical Load Calculator
ElectricalElectrical Load Calculator
Estimate the calculated load of a house in volt-amps and amps at 240 V, from its area, appliances and heating or cooling.
Calculated load at 240 V
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How to calculate the electrical load of a house
Building departments in California publish a worksheet for the optional method of calculating the load of a house (section 220.82 of the California Electrical Code). This calculator follows that worksheet line by line.
| Step | What to count |
|---|---|
| 1. General lighting and receptacles | Floor area in ft² × 3 VA |
| 2. Kitchen and laundry circuits | 1,500 VA for each kitchen appliance circuit (at least 2) and each laundry circuit (at least 1) |
| 3. Appliances and fixed loads | Nameplate rating of the range, oven, water heater, dishwasher, disposal, dryer and others |
| 4. Subtotal A | Add steps 1, 2 and 3 |
| 5. Total A | The first 10,000 VA at 100%, plus 40% of everything above 10,000 VA |
| 6. Total B | The largest heating or air conditioning load, after its percentage |
| 7. Service load | (Total A + Total B) ÷ 240 volts = amps |
We read the worksheets in October 2026: County of Placer, Building Services Division (2022 California Building Standards Code) and Town of Truckee, Building & Safety Division (2025 edition). They agree on the numbers. An article in IAEI Magazine (2013) describes the same method in the National Electrical Code, and says it applies to a dwelling unit with a single 120/240-volt or 208Y/120-volt 3-wire service with an ampacity of 100 or greater. We did not copy the code. The edition and the local amendments in your area can differ from these sources, so your local building department has the final word.
Example: a 2,000 ft² house
A house of 2,000 ft² with 2 kitchen appliance circuits, 1 laundry circuit, a 10,000 W range, a 4,500 W water heater, a 5,000 W dryer, a 1,200 W dishwasher and 4,800 W of air conditioning. The button "Fill in the example house" loads these numbers.
| Step | Operation | Result |
|---|---|---|
| Lighting and receptacles | 2,000 × 3 | 6,000 VA |
| Kitchen circuits | 2 × 1,500 | 3,000 VA |
| Laundry circuit | 1 × 1,500 | 1,500 VA |
| Range, water heater, dryer, dishwasher | 10,000 + 4,500 + 5,000 + 1,200 | 20,700 VA |
| Subtotal A | 6,000 + 3,000 + 1,500 + 20,700 | 31,200 VA |
| Remainder at 40% | (31,200 − 10,000) × 0.4 | 8,480 VA |
| Total A | 10,000 + 8,480 | 18,480 VA |
| Total B, air conditioning | 4,800 × 100% | 4,800 VA |
| Total service load | 18,480 + 4,800 | 23,280 VA |
| Amps | 23,280 ÷ 240 | 97 A |
As a check, the Placer County worksheet includes its own worked sample: a 2,800 ft² home with a 12 kW range, a 3 kW water heater, a 5 kW dryer, a 1.5 kW dishwasher, a 7 kVA EV charger and 6.96 kW of air conditioning. It comes to 29,520 VA and 123 A. The calculator returns the same result for those numbers.
Lighting and fixed circuits by floor area
The first three lines of the calculation depend only on the area and on the circuits. This table adds lighting and receptacles at 3 VA per ft² to 4,500 VA for two kitchen circuits and one laundry circuit.
| Floor area | Lighting and receptacles | With 3 fixed circuits |
|---|---|---|
| 1,000 ft² | 3,000 VA | 7,500 VA |
| 1,500 ft² | 4,500 VA | 9,000 VA |
| 2,000 ft² | 6,000 VA | 10,500 VA |
| 2,500 ft² | 7,500 VA | 12,000 VA |
| 3,000 ft² | 9,000 VA | 13,500 VA |
| 4,000 ft² | 12,000 VA | 16,500 VA |
How the first 10,000 VA and the 40% work
Subtotal A is cut in two. The first 10,000 VA count in full and the part above that counts at 40%.
| Subtotal A | Remainder above 10,000 VA | Remainder at 40% | Total A |
|---|---|---|---|
| 10,000 VA | 0 VA | 0 VA | 10,000 VA |
| 15,000 VA | 5,000 VA | 2,000 VA | 12,000 VA |
| 20,000 VA | 10,000 VA | 4,000 VA | 14,000 VA |
| 30,000 VA | 20,000 VA | 8,000 VA | 18,000 VA |
| 40,000 VA | 30,000 VA | 12,000 VA | 22,000 VA |
| 50,000 VA | 40,000 VA | 16,000 VA | 26,000 VA |
If Subtotal A is under 10,000 VA, the worksheet does not say what to do. The calculator counts what is there, so Total A equals the subtotal.
Heating and air conditioning
The worksheets say that the largest of the following is included, and the calculator picks it after applying each percentage.
| Load | Counted at |
|---|---|
| Air conditioning and cooling | 100% of nameplate |
| Heat pump without supplemental heating | 100% of nameplate |
| Heat pump with supplemental electric heating | 100% plus 65% |
| Electric space heating, fewer than 4 separate units | 65% of nameplate |
| Electric space heating, 4 or more separate units | 40% of nameplate |
| Electric thermal storage and other | 100% of nameplate |
For the heat pump with supplemental heating the worksheets only say "100% NP rating plus 65%". The IAEI article says the 65% is for the supplemental electric heating that goes with the heat pump compressor, so the calculator counts 100% of the heat pump and 65% of the supplemental heat. The IAEI article adds that if the compressor is prevented from running at the same time as the supplemental heat, it does not need to be added. This calculator always adds both, which gives the higher figure. Confirm that reading with your inspector.
What this calculator does not do
It follows one worksheet for a single-family house. It does not use the standard method of the code, it does not handle commercial buildings, and it does not choose the size of the service or the panel. It does not size breakers or wire. For a breaker, see the breaker size calculator. To turn a wattage into amps, see the watts to amps calculator, and for apparent power, the kVA calculator. The electrical code adopted where you live sets the final rules, and a licensed electrician should do the real calculation. Nothing you type leaves your browser.
Frequently asked questions
How do you calculate electrical load?
The optional method in the worksheets we read goes in steps. Count 3 volt-amps per square foot for lighting and receptacles, 1,500 volt-amps for each kitchen appliance circuit (at least 2) and each laundry circuit (at least 1), and the nameplate rating of the appliances. Take the first 10,000 volt-amps at 100% and the rest at 40%. Add the largest heating or cooling load. Divide by 240 volts to get amps. For example, 23,280 VA ÷ 240 = 97 amps.
Can I calculate my electrical load online?
You can get an estimate with this page, which follows the worksheet that two California building departments publish. It is not a permit document. A licensed electrician or your local building department decides which method and which code edition apply, and what the result means for your service.
How do I calculate the load for a 100 amp electrical panel?
Run the calculation and compare the amps in the result with 100. The method has a limit of its own. The IAEI article we read says the optional method is for a dwelling unit with a single 120/240-volt or 208Y/120-volt 3-wire service with an ampacity of 100 or greater. Whether a given result is acceptable for a panel is a decision for a licensed electrician and your local building department. This page does not choose a service or panel size.
How many volt-amps per square foot do I count for lighting?
The worksheets count 3 volt-amps per square foot for general lighting and receptacles. A 2,000 square foot house is 2,000 × 3 = 6,000 VA. The IAEI article says the area is based on the outside dimensions of the dwelling.
Are watts the same as volt-amps in this calculation?
The worksheets convert nameplate watts to volt-amps one to one, which assumes a power factor of 1. So 4,500 W on a nameplate is entered as 4,500 VA. If the nameplate is in kilowatts or kVA, choose the kVA or kW option in the calculator and it multiplies by 1,000.
Where does an EV charger or a hot tub go?
Use the "Other loads" rows. The worksheets list permanently connected motors, appliances fastened in place and an electric vehicle charger under "Other", entered at the nameplate rating. Type a name and the rating, and add more rows if you need them.
Why is only one heating or cooling load counted?
The worksheets say that the largest of the heating and air conditioning options is included, so the calculator picks the largest after applying each percentage. If you have both air conditioning and electric heating, only the larger counts. Ask a licensed electrician if your system mixes several types.
More calculators
- Breaker Size Calculator Minimum breaker rating for a load in amps, watts or kW, using the 125% rule for continuous loads.
- Watts to Amps Calculator Convert watts to amps (and amps to watts) for DC, single-phase and three-phase circuits.
- kVA Calculator Convert amps to kVA, kW to kVA, kVA to amps and kVA to kW for single-phase and three-phase circuits.