Generator Fuel Usage, Runtime & Cost Calculator
Estimate how much fuel your generator will use, how long your fuel supply will last, and what it could cost to operate during a power outage.
Generator fuel consumption can add up surprisingly quickly during an extended outage. Use the calculator below to estimate fuel usage per hour, fuel needed per day, total runtime, operating cost, and multi-day fuel requirements.
For the best estimate, use the fuel-consumption rate published by your generator manufacturer at a load percentage similar to how you plan to operate the generator.
Generator Fuel Calculator
Enter your generator and fuel information below.
What Does the Generator Calculator Tell You?
The calculator combines your generator’s fuel-consumption rate with the amount of fuel you have available and the number of hours you expect to operate the generator each day.
That allows you to answer several important questions before an outage:
- How many gallons of fuel will my generator burn each day?
- How long will my stored fuel last?
- How much could it cost to operate my generator for 24 hours?
- How much fuel should I have for a three-day or seven-day outage?
- How heavily am I loading my generator?
Example: 5,000-Watt Generator
Suppose you have a 5,000-watt gasoline generator supplying an average load of 2,500 watts.
If the generator consumes approximately 0.50 gallon per hour, running continuously would consume:
If you had 20 gallons of gasoline available, the generator could theoretically provide approximately:
But if you only operate the generator for 10 hours each day, those same 40 operating hours could cover approximately four days of outages.
Running a Generator Fewer Hours Can Dramatically Extend Your Fuel
A generator does not necessarily need to operate 24 hours per day during an outage. Many homeowners can conserve fuel by operating the generator during periods when refrigerators, freezers, pumps, furnaces, air conditioners, cooking appliances, or other major loads need electricity.
Battery storage or a portable power station can then supply smaller loads between generator cycles.
Where Do I Find My Generator’s Fuel Consumption?
Check the generator’s owner’s manual, manufacturer’s website, specification sheet, or product listing. Manufacturers often publish runtime at a specified electrical load.
For example, a generator specification might say:
You can estimate hourly fuel consumption by dividing fuel capacity by runtime:
Enter 0.50 into the Fuel Consumption field in the calculator.
Generator Safety Reminder
Never operate a portable generator inside a house, garage, basement, shed, enclosed porch, or other enclosed structure. Portable generators produce carbon monoxide, which can be deadly.
Operate your generator outdoors according to the manufacturer’s instructions and maintain working carbon-monoxide alarms inside the home.
Never refuel a hot or running gasoline generator. Shut the generator down and allow it to cool before adding fuel.