Backup power planning

Generator Runtime Estimator

Use your generator’s manufacturer fuel-use table and a realistic essential-load list to plan runtime and reserve fuel.

These planning tools need JavaScript to calculate results. You can still use the linked guides and safety sources on this page.

Carbon-monoxide safety: generators stay outdoors only

Never run a generator inside a home, garage, basement, shed, or near doors, windows, or vents. Use working carbon-monoxide alarms and follow the manufacturer manual.

Estimate runtime from your manual

Enter the fuel-use figures printed for your generator at 25%, 50%, and 75% load. This tool does not substitute a generic fuel-burn formula.

Fuel and generator rating

GasolineDieselPropane (liquid gallons)

Available fuel

Fuel available for this outage, in liquid gallons.

Rated running watts

Use the running-watts rating, not starting/surge watts.

Essential loads

The calculator remains within the 25-75% manufacturer data band. Reduce loads if your selected essentials exceed 75% of rated running watts.

Refrigerator150 W running loadLED lights60 W running loadInternet / phone charging45 W running loadMedical device120 W running loadSump pump800 W running load

Custom load watts

Optional running watts not listed above.

Manufacturer fuel-use figures

Copy these values from the manufacturer manual for the exact generator and fuel type. Units are gallons per hour.

At 25% load

At 50% load

At 75% load