Home Standby Generator Fuel Burn & Runtime

Estimate how long your standby generator can power critical loads, the kilowatt-hours it will deliver, and the fuel bill for a full tank cycle.

Average kilowatt draw you expect the generator to support during an outage.
Usable fuel available between fills or deliveries in gallons.
Gallons consumed per hour at the stated load according to manufacturer specs.
Delivered price per gallon of propane, diesel, or natural gas equivalent.

For planning purposes only. Follow manufacturer and safety guidance when operating generators.

Examples

  • 18 kW load, 250-gallon propane tank, 2.1 gal/hour burn, $2.85/gal ⇒ Runtime 119.05 hours (4.96 days) and $5.99/hour fuel cost.
  • 14 kW load, 100-gallon diesel tank, 1.3 gal/hour burn, $4.10/gal ⇒ Runtime 76.92 hours (3.21 days) and $5.33/hour fuel cost.

FAQ

How do I adjust for partial loads?

Use the burn rate published for the percentage of load you expect to carry, or average across light and heavy load scenarios and rerun the calculation.

What if I refuel before the tank is empty?

Enter the gallons you plan to consume between deliveries instead of total tank capacity to model shorter runtime windows.

Does the tool include maintenance intervals?

No — schedule oil changes or rest periods separately; the output focuses on runtime and fuel costs only.

How can I estimate carbon monoxide or emissions impacts?

Multiply the reported energy delivered and fuel consumption by published emission factors from your generator manual to approximate CO₂ or pollutant loads.

Additional Information

  • Fuel burn rate should reflect the expected load; partial loads burn less than rated values.
  • Runtime is calculated using tank capacity divided by hourly burn with no reserve; maintain safety margins for sediment and regulator limits.
  • Fuel price is multiplied across the entire tank to highlight the cost of a prolonged outage.
  • Daily fuel draw equals burn rate × 24, helpful for scheduling deliveries during multi-day outages.

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