Generator Fuel Calculator
Size the generator, pick how hard it will actually work - a fridge, lights and router sit near 25-50% on a 5000 W unit - and set the hours you want to cover. You get the burn rate per hour, total gallons, the cost at your pump price, and how many 5-gallon cans that means.
Dealer pages sell capacity and skip the fuel ledger entirely, yet fuel is what decides whether the generator is a tool or a porch ornament. The field rule - 0.18 gallons per hour per kilowatt at full load, scaled by your load - lands within a quarter of real tanks, and the page pairs it with the storage and refueling rules that prevent the classic storm-week mistakes.
How to use
- Pick the generator size you own or are planning to buy or rent.
- Be honest about load - most homes never average above 50%.
- Set outage hours and your local gas price; the cans figure rounds up.
Frequently asked questions
How much gas does a 5000 watt generator use per day?
At a realistic 50% load, about 0.45 gallons per hour or 11 gallons a day - two and a bit 5-gallon cans. At 25% (fridge, lights, router) it falls to around 5-6 gallons; running everything at once can double it.
How long can you store gasoline for a generator?
Three to six months untreated, a year or more with fuel stabilizer. Rotate the stock by pouring it into the car and refilling - an outage is the wrong time to discover last season went stale.
Is a generator cheaper to run than a battery power station?
Per hour of heavy load, gasoline wins on cost. Per outage over years, the battery wins on silence, fumes, maintenance and indoor safety. The honest split: generators for multi-day whole-home events, stations for day-long rides and apartment use.
Can I refuel a generator while it is running?
Never - a hot engine plus a spilled gallon is the textbook flash fire. Shut down, wait 10-15 minutes, refuel with a funnel, restart. Fifteen minutes of darkness is cheaper than the alternative.