Skip to content

Whole-House Backup Load Calculator

Dwelling demand the NEC 220.82 optional method way, then the generator kW that covers it with and without load management.

Inputs

Inputs and assumptions

NEC 220.12 minimum is 3 VA/ft2 for dwellings.

1500 VA each.

1500 VA each.

Dishwasher, disposal, microwave, furnace blower, garage door.

Horsepower. 0 when there is no pump.

Nominal tons. Roughly 1.2 kW of input per ton.

0 when heating is gas, propane, or a heat pump listed under A/C.

NEC 625.42 counts EVSE at 100%.

Typical essentials-only design sheds 25-40% of dwelling demand.

Result

General lighting and receptacle demand
—
Generator with load management
—
Calculated service load
—
Calculated dwelling demand
—
Generator for whole-house coverage
—

What to check

  • Twelve months of metered usage and peak demand
  • Nameplate ratings for range, dryer, water heater, A/C, and EV charger

Related calculators

Screening-grade estimate built from labeled inputs and stated defaults. Verify the nameplate data, manufacturer fuel tables, adopted code edition, and installer quotes before you buy, wire, or run anything.

Saved calculations

Keep the assumptions with the result.

Save this calculation to return to the inputs, result, and report anytime.

Sign in or create an account to save this calculation.