How Much Gasoline Does a Generator Use?

Gasoline is the most commonly used fuel to operate generators, and many generators today have a dual fuel capacity, and owners use the gasoline option more often than propane. Each generator model comes with a standard estimate of fuel use or how many hours the generator may run on the fuel supply.

However, be aware that each generator model will have different specifications, and based on the power of the engine and wattage output, this is only an estimate. Every generator can use more-or-less, and peak load will use more gasoline than running. 

A minor power draw will require less fuel use, as the engine is not working as hard. Therefore, most generator specs show the number of hours their fuel tanks should run at either 25 or 50 percent power draws.

It is good to know how much fuel your generator will use, so you can figure how much it will cost to operate it. In general, the following table will give you an idea of the gallons of gasoline required to run a small-watt generator and the hours the engine may be able to run. Note that the average wattage listed is 2000-2400 for comparison using manufacturer specs.

Brand/Model Peak Watts Running Watts Fuel Capacity Operating Hours/Load
Briggs & Stratton P2400240018001.0 gallon8 hours @ 25%
Champion Model 100402200016001.1 gallon11 hours @ 25%
Duromax XP2000EH200016001.19 gallon6.78 @ 50%
Generac GP2200i220017001.2 gallon7 hours @50%
Honda EU2200iTAN22001800.95 gallon8.1 hours @ 25%
Predator 2000200016001.0 gallon12 hours @ 25%
WEN 2000W200016001.0 gallon9.4 hours @ 25%
Westinghouse iGen2200220018001.2 gallon10 hours @ 25%
Yamaha EF2000ISV2200016001.1 gallon10.5 hours @ 25%

Cost of Gasoline

The cost of gasoline will vary by state as gasoline taxes include the cost of infrastructure repairs as determined by legislature budgets. Gasoline costs across the U.S. fluctuate by supply and demand but stay within an average national range.

In most instances, gasoline will be cheaper to purchase than propane, although those prices can vary, as well.

Gasoline Generators vs Propane Generators

Dual fuel generators give you the option of using gasoline or propane. Propane is not as efficient as it produces fewer BTUs, but it burns cleaner than gas. As its efficiency is not as good, the number of hours a gallon lasts will be less. 

Refilling propane depends on the size of the tank used. With the right connections, a generator can run longer between refills if connected to a larger propane tank, such as a 20-gallon or 100-gallon size.

While gas is relatively easy to get at any gas station, remember that pumps run on electricity. If a power outage is widespread, access to an operating pump at the station may be difficult. Plan ahead.

Since generator fuel tanks are limited, manually refilling the tanks within the specified operating times is important. Depending on your power needs, this may need to be filled several times a day.

Gasoline does not burn as clean as propane and can leave carbon deposits in the engine and produce toxins into the air through the exhaust. Remember to operate a generator in a well-ventilated space and perform regular maintenance on the machine to keep it running smoothly.

Gas has a shorter shelf life and will degrade if not used within a year. Propane does not go bad, so there are no concerns about monitoring its shelf life.

Check out a similar post we wrote regarding how much propane a generator uses.

Safety Considerations

As with any power equipment, operating your gas-powered generator requires safety precautions. 

  • Gasoline is highly combustible, so always turn off the generator and allow it to cool before refilling the fuel tank. The heat from the engine could cause a fire if gasoline spills on the hot surface.
  • If using a gas-powered generator in a wilderness area where fire danger is a consideration, use caution. Gasoline is an accelerant.   If gas spills on the ground, use a rake or shovel and cover it with dirt to prevent exposure in the event of a wildfire.
  • Keep gasoline containers tightly sealed and away from fire or heat between uses, as fumes can ignite.
How Much Gasoline Does a Generator Use


How long will a generator run on a gallon of gas?

It depends on two basic things: 1) the watt-output of the generator and 2) the running load. Most references on how much gasoline a generator uses report averages of three-quarters a gallon per hour at normal load. The more power required of the engine, the more gasoline it will use.

Spec sheets vary by generator brand and model, and the hours of operation show a quarter to one-half percent of total wattage draw. Operating at full power will significantly reduce how many hours the fuel will last.

How much does it cost to run a generator on gasoline?

Each generator will be different. The manufacturer’s spec sheet will note how many hours the fuel should last, based on a 25% or 50% load draw. Using those percentages and calculating if you will run at full power using the running wattage, you should be able to figure how much gasoline you need.

For example, if you have a 1-gallon fuel tank and the specs state that you should get five hours at 50% load, and you need to run the generator for five hours at running load, you need two gallons of fuel. 

Calculate the number of gallons times the current price per gallon of gasoline to figure how much it will cost to run the generator.

How long will a generator run on a full tank of gas?

The answer is, it all depends. Each generator has its specs from the manufacturer that are guidelines to how long a tank of gas should last. The specs are all listed using a percentage of normal or running load. The size of the fuel tank, how many watts of power are used, and the length of time will depend on your use.

Operating at full load will use gas quicker than running minimal appliances or lights at a reduced load, thereby reducing how long the generator can work on a tank of gas.

Is it cheaper to run a generator on gas or propane?

On the one hand, gasoline is usually cheaper to purchase per gallon than propane. On the other hand, propane burns more efficiently than gasoline, so there is minor wear and tear on the engine. Gasoline leaves carbon debris in the engine and expels toxins through the exhaust.

Gasoline is typically easier to access, available at every service station. Accessing propane can be more difficult as not every station carries a supply.

About Chad & Rick

Chad and Rick are the father son team behind Generator Hero. Rick is an engineer and manager, he’s used generators his whole life and specializes in fact checking our articles. Chad is a writer and webmaster helping to keep things running smoothly on the site. Read more about Rick and Chad, or send a message using this contact form.

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