Enter your generator's rated wattage, fuel type, and load level to estimate burn rate, tank runtime, and fuel cost per day.
Burn rate uses typical portable-generator fuel curves at partial load. Your unit's actual spec sheet is more accurate if available.
Fuel burn scales roughly with load, not just rated size — a generator running at 25% load burns meaningfully less per hour than the same unit at 100%, which is why oversizing "just in case" quietly costs more in fuel over a multi-day outage. If you're deciding between running a generator or leaning on stored capacity, compare this against a battery backup runtime estimate for the same loads.
Propane has lower energy density than gasoline, so generators burn more gallons (or pounds) of it per hour for the same output — but propane stores indefinitely without degrading, which gasoline doesn't.
Engines are least efficient at very light loads relative to their capacity, and burn scales up from there — running a 10kW generator at 20% load to power a fridge is much less efficient than sizing closer to actual demand.