Generator Fuel Consumption Calculator

Generator Fuel Consumption Calculator

Generator fuel consumption scales with actual delivered load, not just the generator's rated capacity - this calculator accounts for that relationship to give a realistic fuel usage estimate.

Formula

1. Actual Load = Rated Power x Load%
2. Energy Generated (kWh) = Actual Load x Run Hours
3. Total Fuel = Energy Generated x Fuel Consumption Rate (L/kWh)

Example

A 100 kW generator running at 50% load for 10 hours, at 0.3 L/kWh:

Actual Load = 50 kW → Energy = 500 kWh → Fuel = 150 liters

Why Oversizing Hurts Fuel Economy

Generators are notably less fuel-efficient at low partial loads than when running near their rated capacity - a generator running at just 25% load doesn't use anywhere near 25% of its full-load fuel consumption, since a meaningful portion of fuel burn goes toward simply running the engine regardless of electrical output. This is exactly why oversizing a backup generator well beyond actual typical demand often results in unexpectedly poor real-world fuel economy compared to properly sized equipment.