Generator Fuel Consumption
Calculator
Results
- Output power (kW)
- 15
- Energy produced (kWh)
- 120
- Fuel used (L)
- 33.6
- Fuel rate (L/h)
- 4.2
Energy results
| Output power (kW) | 15 |
| Energy produced (kWh) | 120 |
| Fuel used (L) | 33.6 |
| Fuel rate (L/h) | 4.2 |
formula-map diagram
- Output power (kW)
- 15
- Energy produced (kWh)
- 120
- Fuel used (L)
- 33.6
- Fuel rate (L/h)
- 4.2
Energy relationship
Formula
Fuel(L) = kW_rated × load factor × hours × SFC= 15
Note
This is a simplified model: it applies the standard equation to the numbers you entered and ignores real-world losses, weather variation, tariff structures and equipment tolerances. Wind power assumes air density 1.225 kg/m³ at ISA sea level and the power coefficient you enter (Betz limit 0.593). Verify with measured data or a professional energy audit before making purchasing decisions.
More in Energy and environment
See all →Frequently asked questions
What load level should I use for the estimate?+
Use your expected average running load, not the generator's maximum rated capacity, since fuel consumption scales with load and generators are typically most efficient at 50-75% of rated output. Running near maximum capacity for extended periods also increases wear.
Why does fuel consumption not scale linearly with load?+
A generator burns some fuel just to keep its engine running regardless of electrical load, so at low loads the fuel-per-kWh cost is relatively high. Efficiency improves as load increases toward the sweet spot, then can worsen again near maximum capacity.
How do I estimate runtime from a tank of fuel?+
Divide your fuel tank capacity by the estimated consumption rate in gallons or liters per hour at your expected load. A generator using 0.75 gallons per hour with a 5-gallon tank, for instance, runs for roughly 6.5 hours before refueling.
Does fuel type change the consumption figures?+
Yes, gasoline, diesel, and propane generators have different fuel-to-energy efficiencies, with diesel generally providing more energy per gallon than gasoline. Manufacturer fuel consumption charts are specific to fuel type, so mixing up the numbers gives an inaccurate estimate.
Why does my actual fuel use run higher than the calculator's estimate?+
Cold starts, altitude, poor maintenance, and running above the generator's efficient load range can all increase real-world fuel burn above published figures. Manufacturer consumption charts are typically measured under controlled, well-tuned conditions.