Backup Generator Runtime Calculator
Estimate generator runtime based on fuel tank size, connected load, and fuel type. Calculate fuel consumption and operating costs.
Inputs
W
gal
W
Results
Estimated Runtime
15.1 hours
Fuel Consumption0.4 gal/hr
Load Percentage47%
Cost per Hour$1.39
Full Tank Cost$21
How to Use This Calculator
- Enter Generator Watts (the rated output on the nameplate) and Fuel Tank Gallons for your generator model.
- Select Fuel Type (propane, natural gas, or gasoline) as each has different energy density and consumption rates.
- Enter Connected Load Watts — the total wattage of appliances you plan to run during an outage.
- Review Runtime Hours to see how long your fuel supply will last at the specified load level.
- Check Load Percent to ensure the generator is loaded between 50–80% for efficient operation and longevity.
- Use Cost per Hour and Total Fuel Cost to plan outage budgets and compare generator options.
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