Calculators
Electrical Load Calculator
Estimate a home's electrical load in VA and amps with a demand-factor method and the service size it suggests.
- Runs in your browser
- Nothing uploaded
The tool
Enter your numbers below. Results update as you type, and nothing leaves your browser.
Everything you enter stays on your own machine. Nothing is sent to us or to anyone else, which you can confirm in your browser network tab.
What people use it for
- Checking whether a panel can take an EV charger
- Planning a service upgrade
- Estimating loads for an extension
- Electrician pre-quotes
About this tool
What the Electrical Load Calculator does
A residential load calculation adds up general lighting, small appliance and laundry circuits, fixed appliances and heating or cooling, then applies demand factors because not everything runs at once. This calculator follows the shape of the US NEC optional method: the first 10 kVA at 100% and the rest at 40%, with the larger of heating or cooling added in full.
It also works as a load calculator or a service size calculator.
Formula
- General load = area × 3 VA + 1,500 VA per small appliance and laundry circuit + appliance nameplates
- Demand = first 10,000 VA at 100% + remainder at 40%
- Total = demand + larger of heating or cooling; amps = total ÷ voltage
Worked example
Using the starting values in the calculator above:
| Input | Value |
|---|---|
| Living area | 2,200 sq ft |
| Small appliance circuits | 2 |
| Laundry circuits | 1 |
| Fixed appliances | 6 entries |
| Heating load | 10,000 VA |
| Air conditioning load | 5,000 VA |
| Service voltage | 240 |
| Result | Value |
|---|---|
| Calculated load | 126.7 |
| Smallest standard service that covers it | 150 A |
| Total demand load | 30,400 |
| General load before demand factor | 36,000 |
| General load after demand factor | 20,400 |
How to read the result
Planning an EV charger, heat pump or electric range? Add them as appliances to see whether the existing service can carry them.
Utilities and inspectors require the full code method for service changes; use this to decide whether a formal calculation is worth commissioning.
For planning only. Electrical, gas and refrigerant work must follow current codes and be carried out or checked by a licensed professional.
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Questions
Questions about this tool
The things clients actually want to know — costs, timelines, ownership and what happens after launch.
Add general lighting at 3 VA per square foot, small appliance and laundry circuits, appliance nameplates and heating or cooling, then apply demand factors.
Often not for homes with electric heating, an EV charger or several large appliances; the calculation shows your situation.
An allowance for the fact that not all loads run at full power at the same time.
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