Generator Fuel Efficiency Calculator
What this calculator measures
Calculate electrical kWh per US gallon from matched average electrical output and liquid-fuel consumption. Measured fuel and load already reflect fuel type and equipment condition, so no category multipliers are applied.
Inputs and units
Use readings and ratings that describe the same equipment, operating interval, and measurement boundary. The sample entries are editable examples; they do not establish the specifications of your generator.
| Input | Example entry or choice |
|---|---|
| Generator Size (kW) | 100 — enter a documented value |
| Average Load (%) | 75 — enter a documented value |
| Actual liquid-fuel consumption at that load (US gal/h) | 7.5 — enter a documented value |
Calculation method
Electrical kWh per US gallon = average electrical kW ÷ actual US gallons per hour. Average kW is applicable rated kW multiplied by the corresponding average load fraction. Use output and net fuel consumption from the same period and operating condition.
Worked example
For 100 kW rated output, 75% average loading, and 7.5 US gal/h actually consumed, productivity is 10 kWh/US gal. Equivalently, 600 kWh and 60 US gallons over an eight-hour interval give the same ratio.
Limitations and checks
This is a volume-based productivity measure, not a percentage of fuel energy converted to electricity. Different fuels contain different energy per gallon, so compare energy efficiencies on an appropriate heating-value basis. Natural gas measured in cubic feet or cubic metres should not be relabelled as liquid gallons.
For a practical decision, keep the original readings, the generator model, the relevant manual or specification, and the assumptions alongside the result. A different load, site condition, rating basis, or unit convention can answer a different question even when the arithmetic is correct.
Sources and methodology
Publisher: CSP Digital Media Ltd. To report a formula, unit, or example error, contact us with the tool name, inputs, displayed result, and expected calculation.