Generator runtime and fuel calculator in litres

Preliminary estimate

Inputs

Calculation note

Runtime uses an editable fuel-use factor. Manufacturer fuel curves should replace the default factor when available.

Method

L/h = load kW x litres per kWh

Usable litres = tank litres x (1 - reserve percent / 100)

Runtime hours = usable litres / L/h

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Formula variables

  • Load kW is the expected running electrical load.
  • Litres per kWh is an editable fuel-use factor.
  • Tank litres is the gross fuel volume entered by the user.
  • Reserve percent is kept out of the usable runtime estimate.

Assumptions

  • Fuel use is estimated from electrical load in kW and an entered litres-per-kWh factor.
  • Usable fuel subtracts the reserve percentage from tank volume before runtime is calculated.
  • Actual fuel consumption varies by generator model, load factor, maintenance, altitude, fuel, temperature, and transient loading.
  • Standby systems, healthcare/emergency systems, and CSA C282-style requirements need project-specific design and maintenance review.

Examples

50 kW standby load. A 50 kW load at 0.28 L/kWh with a 400 L tank and 15 percent reserve estimates 14 L/h and about 24.29 hours runtime.

Refuelling workflow. Use the runtime output to plan refuelling intervals, then confirm actual consumption against the generator manufacturer data.