Residential Load Calculator — NEC 220.82

The NEC 220.82 optional method is the practical route for a single dwelling. Add 3 VA per square foot of living area, 1,500 VA for each small-appliance circuit (minimum two) and each laundry circuit (minimum one), plus the nameplate rating of every fastened-in-place appliance. Take the first 10,000 VA at 100% and everything above that at 40%. Then add the largest of the heating or cooling options from 220.82(C) at its stated percentage. Divide the total by 240 for amps.

The standard method (220.40 through 220.55) itemises every load and applies a separate demand factor to each category — general lighting, ranges, dryers, motors — and is required for multi-family and commercial work. The optional method (220.82) is a simplified path available for a single dwelling served at 100 A or more: one broad demand factor covers everything except heating and cooling. The optional method is usually the smaller answer, which is why it is what most residential electricians run.

Because nothing in a house runs at once. The range, the dryer, the water heater, and the dishwasher all have full nameplate ratings, but the odds of all of them peaking simultaneously are negligible. The 40% demand factor is the Code's statistical allowance for that diversity, and decades of field experience support it — houses with 24,000 VA of calculated load routinely peak under 60 A in real metering.

Yes, as a fastened-in-place appliance in the general load — where it then benefits from the 40% remainder factor. This is why adding an EV charger often does not require a service upgrade: a 48 A charger is 11,520 VA of nameplate but only adds about 4,600 VA to the calculated load once the 40% factor applies. Some jurisdictions require EVSE to be treated separately or demand an energy management system instead — check locally, and see the EV Charger Circuit Calculator.

A typical 2,000 sq ft home with gas heat, an electric range, dryer, and water heater calculates to about 101 A, which technically fits a 125 A service. Almost nobody installs 125 A — 200 A is the practical standard because it costs little more and leaves headroom for an EV charger, a heat pump, or an induction range later. Go all-electric on that same house and the calculation jumps past 150 A.

For a gas-heated house with modest electric appliances, often yes on paper. For an all-electric house, or one adding EV charging and a heat pump, usually no. The honest test is to run the calculation, not to guess from the panel label. If the existing service is 100 A and you have twelve months of utility data, NEC 220.87 lets you use measured peak demand instead of the estimated calculation, and it frequently proves the existing service is adequate.

The calculation itself is arithmetic anyone can follow, and this tool reproduces it faithfully. But the inputs require judgement — what counts as living area, which appliances are fastened in place, whether heating and cooling can operate simultaneously — and the output is normally part of a permit submittal that a licensed electrician signs. Use this to understand and sanity-check the number; have a licensed electrician confirm it before anyone specifies equipment or pulls a permit.