Generator Fuel Consumption Calculator

What drives generator fuel consumption

Fuel burn scales with the load, not the rated capacity. A set running at half load burns roughly two thirds of what it burns at full load — not half, because a diesel engine loses efficiency at part load. That is why consumption per kWh is worse at light load, and why the calculator shows both figures.

Typical values for small air-cooled sets: about 0.27 L/kWh at full load for a 10 kW machine, rising to roughly 0.40 L/kWh for a 5 kW set at full load, because smaller single-cylinder engines are less efficient.

How to reduce running costs

• Run in the 60–80% band. This is where a diesel engine is most efficient and stays hot enough to avoid wet stacking.
• Match the set to the load. Using a 15 kW machine for a 4 kW job costs far more than using a 5 kW machine.
• Keep filters and injectors clean. A clogged air filter alone can add several percent to fuel burn.

Common questions

How much fuel does a generator use per hour?

A 10 kW diesel set at 60% load burns roughly 1.9 litres per hour. Our calculator gives you the exact figure for your rated power, load and fuel type.

Do gasoline generators use more fuel?

Yes — roughly 25 to 30% more per kWh than an equivalent diesel, which is why diesel dominates for anything beyond occasional standby use.