Fuel & Tanks
Generator Fuel Consumption Calculator
How much fuel will your generator burn, and how long will it run? Calculate gallons per hour and total runtime for gasoline, propane, or diesel generators. Free.
Frequently asked questions
How much propane does a generator use per hour?
A standby generator burns roughly 1–3 gallons of propane per hour depending on size and load. A 22 kW unit at half load uses around 1.9 gallons per hour; a small 7 kW portable closer to 0.6. Diesel generators are more fuel-efficient; gasoline lands in between.
How long will a generator run on a 20-lb propane tank?
A 20-lb cylinder holds about 4.6 gallons of propane. A small 3.5 kW generator at half load (~0.3 gal/hr) would run roughly 15 hours; a larger unit far less. For whole-home backup you’ll want a much larger tank.
How much gas does a generator use per day?
Running 12 hours a day, a 7 kW gasoline generator at half load uses about 5–6 gallons; running continuously, 10–12 gallons. Multiply the per-hour figure above by the hours you actually run it.
How much fuel should I store for a 3-day outage?
Estimate your per-hour burn at your expected load, multiply by the hours per day you’ll run the generator, then by three. Most households run a generator intermittently rather than 24/7, which stretches stored fuel considerably — the calculator above does this math for you.
Is propane or diesel more efficient for a generator?
Diesel delivers the most energy per gallon and is the most fuel-efficient, which is why it’s common for large or long-run applications. Propane stores indefinitely without degrading and burns cleanly, making it popular for standby home units. Gasoline is convenient but stores poorly.