Whole-Home Generator Fuel Budget Calculator

Budget generator fuel before a storm hits. Enter consumption at your expected load and the outage window to reveal gallons required, total fuel spend, storage endurance, and whether you need deliveries to stay powered.

Expected consumption at planned load.
Number of hours you want backup power available.
Defaults to $4.50 if blank.
Propane or diesel storage capacity. Defaults to 0 to skip.

Consult your installer for precise load-specific consumption and safe storage practices.

Examples

  • 2.8 gal/hr burn, 48-hour outage, $4.25 fuel, 250-gallon tank ⇒ Fuel required: 134.40 gallons • Fuel spend: $571.20 • Storage covers 89.3 hours before refueling • Stored fuel covers the entire outage • Average cost per hour of runtime: $11.90
  • 3.5 gal/hr burn, 72-hour outage, default fuel price, 120-gallon tank ⇒ Fuel required: 252.00 gallons • Fuel spend: $1,134.00 • Storage covers 34.3 hours before refueling • Additional fuel deliveries needed: 132.00 gallons • Average cost per hour of runtime: $15.75

FAQ

How do I handle natural gas generators?

Convert the utility charge per therm into an equivalent per-gallon cost and enter it in the fuel price field so the outputs still reflect dollars per hour.

What if I have multiple tanks?

Sum the usable gallons across tanks and enter the total in the storage field to estimate combined endurance.

Can I include maintenance costs?

Yes—add planned maintenance dollars to the fuel spend output after running the calculation to see the full outage budget.

Additional Information

  • Adjust the burn rate for different load levels—most generators publish a consumption table by kW output.
  • Include fuel delivery minimums in your deficit planning to avoid emergency surcharges.
  • Propane expands in heat, so do not plan to draw down 100% of tank volume in practice.

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