How this calculator works
Estimate generator fuel cost per hour, per outage, and per delivered kWh from consumption, fuel price, load, and maintenance allowance.
Fuel consumption depends on load
A generator usually burns fuel even at low output, so cost per delivered kWh can be high when the unit is lightly loaded. Use a consumption figure from the manufacturer at a load close to your scenario.
Separate operating cost from ownership cost
The calculator covers fuel and an optional maintenance allowance. Purchase, installation, transfer equipment, permits, storage, financing, and depreciation are outside the result.
- Use the correct fuel unit and local price.
- Never operate a combustion generator indoors or in an attached space.
- Follow manufacturer maintenance and load limits.
Safety is not a calculator output
Carbon monoxide, electrical backfeed, fuel storage, grounding, ventilation, and connection requirements need qualified guidance. A cost result does not determine whether an installation or operating practice is safe.
Frequently asked questions
Why is generator electricity expensive per kWh?
Fuel consumption does not fall to zero at light load, and small engines often convert fuel to electricity less efficiently than utility-scale generation.
Does this include propane, gasoline, and diesel?
Yes, if fuel consumption and price use the same unit. The default labels use gallons, so convert other units consistently.
Does this tell me what generator size to buy?
No. Sizing requires continuous load, starting surge, fuel, environment, electrical configuration, and safety considerations.
Use equipment documentation, your utility rate schedule, and measured data when they are available.