Generator Runtime Calculator
Estimate generator runtime from fuel tank.
Result
Formula
Calculation logicFrequently asked questions
How long will my generator run?
Divide tank gallons by consumption at your load fraction. A 5-gallon tank at 0.6 gal per hour gives about 8 hours.
What is load fraction?
Your watts divided by rated watts. Half load is the standard reference point on spec sheets.
Does eco-mode extend runtime?
Inverter generators throttle down at light loads, stretching fuel 20 to 40 percent.
How much fuel should I store?
Plan outage hours times consumption plus 20 percent, rotated yearly for gasoline stability.
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