Home Generator Fuel Burn Budget

Plan for extended outages by sizing generator fuel requirements. Enter the gallons burned per hour at your expected load, the hours you intend to run daily, and today’s fuel price. Optional fields account for extra burn in cold weather and how much fuel you have on site, yielding daily spend, weekly usage, and how many days your reserves will last.

Use the gallons-per-hour rating at the load you expect to run (from the generator spec sheet).
Total hours you expect the generator to operate in a 24-hour period.
Current delivered cost for propane, diesel, or gasoline.
Defaults to 50 gallons if blank. Include tank and portable reserves.
Optional extra burn percentage to reflect harsher operating conditions. Defaults to 0%.

Use manufacturer data and local code requirements when planning standby power. Fuel storage and refueling should comply with local fire and environmental regulations.

Examples

  • 2.1 gph burn, 14 hours runtime, $3.95 fuel, 120 gallons stored, 10% derate ⇒ Adjusted burn rate: 2.31 gallons per hour (10.00% derate applied) • Daily fuel use (14.00 hours): 32.37 gallons costing $127.86 • 7-day outage: 226.58 gallons and $894.99 • Stored fuel runway (120.00 gallons): 3.71 days.
  • 1.6 gph burn, 8 hours runtime, $4.35 fuel, stored gallons blank, derate blank ⇒ Adjusted burn rate: 1.60 gallons per hour (0.00% derate applied) • Daily fuel use (8.00 hours): 12.80 gallons costing $55.68 • 7-day outage: 89.60 gallons and $389.76 • Stored fuel runway (50.00 gallons): 3.91 days.

FAQ

What if my generator runs continuously?

Set runtime to 24 hours. The calculator will scale fuel usage and show how many days your storage will last at continuous load.

Can I model natural gas generators?

Yes. Convert the utility rate to an equivalent dollars-per-gallon figure using energy content, or run the math with therms by multiplying the burn rate and price inputs by the BTU-to-gallon conversion.

How do exercise cycles affect usage?

Add the weekly test runtime into the daily hours input if you want to include routine exercise burns in your fuel plan.

Additional Information

  • Manufacturer fuel curves vary with load; rerun the calculator when you shift from essential circuits to whole-home operation.
  • Propane expands in heat—track usable gallons in 80% full tanks to avoid overestimating reserves.
  • Include derate when temperatures drop below freezing or when operating at elevation, both of which can increase consumption.
  • Pair this with your outage duration assumptions to determine when you need resupply deliveries or larger storage tanks.

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