Generators & Backup Power

Generators & Backup Power calculators — each with the formula, a worked example and a reference table. Results are estimates for planning and education; verify all sizing with a licensed electrician and your AHJ.

Generator Size

To size a generator, add the running watts of everything you'll run at once, then add the …

Appliance Wattage

Appliance wattage is volts × amps. Enter the voltage (120 V for standard US outlets, 240 V…

Generator Fuel / Runtime

Generator runtime is tank capacity divided by fuel consumption: runtime (h) = gallons in t…