Generator Fuel Consumption Calculator
Estimate fuel usage and cost based on generator size, load, and fuel type
How to Use This Calculator
- Enter your generator's rated output in kilowatts (kW).
- Select the load percentage — most generators are most efficient at 50–80% load.
- Choose the fuel type (gasoline, diesel, propane, or natural gas).
- Enter the run time in hours and your local fuel price per unit.
- Read the hourly burn rate, total fuel used, and total cost.
Fuel Consumption Estimates
Estimates use typical brake-specific consumption at the selected load:
Gasoline ≈ 0.11 gal/kWh | Diesel ≈ 0.075 gal/kWh | Propane ≈ 0.16 gal/kWh | Natural Gas ≈ 13.6 ft³/kWh
Hourly burn = Generator kW × Load % × consumption factor. Actual use varies 15–30% by engine efficiency, altitude, and temperature.
| Gen Size | Gasoline (50%) | Diesel (50%) | Propane (50%) | Nat. Gas (50%) |
|---|---|---|---|---|
| 5 kW | 0.28 gal/hr | 0.19 gal/hr | 0.40 gal/hr | 34 ft³/hr |
| 10 kW | 0.55 gal/hr | 0.38 gal/hr | 0.80 gal/hr | 68 ft³/hr |
| 15 kW | 0.83 gal/hr | 0.56 gal/hr | 1.20 gal/hr | 102 ft³/hr |
| 22 kW | 1.21 gal/hr | 0.83 gal/hr | 1.76 gal/hr | 150 ft³/hr |
| 30 kW | 1.65 gal/hr | 1.13 gal/hr | 2.40 gal/hr | 204 ft³/hr |
Generators & Accessories
Frequently Asked Questions
How accurate are these fuel estimates?
They're engineering rules of thumb within 15–30% of real-world use. Actual consumption depends on engine age, load stability, altitude, temperature, and fuel quality. Always confirm against your generator's spec sheet.
Which fuel is most efficient?
Diesel is the most fuel-efficient (highest energy density per gallon), followed by gasoline, then propane. Natural gas offers unlimited supply via utility lines but lower energy density per cubic foot.
Why is running at very low load bad?
Light loads (under 30%) cause 'wet stacking' in diesel engines and carbon buildup in gasoline engines, reducing efficiency and lifespan. Size generators to run at 50–80% load for best economy.