How Long Will a Generator Run on Propane ? – Easy Tips 2023

How Long Will A Generator Run On Propane?

Propane is a slow-burning fuel with a lower burning index (BTU). Therefore, the efficiency of the fuel consumption is relatively high compared with other types of fuel. Propane can run on a generator longer than any other fuel. This makes propane a popular choice for generators. A generator may need 2 – 3 lb of propane per hour of operation. Let’s identify more about this depending on the capacity of propane tanks that are used to feed the generators.

how long will a generator run on propane

20 lb

This is one of the widely available capacities of propane in the market. 20 lb propane tanks are used mostly for generators with a power output of 1 – 3 kW. Although the average time that a generator can run on 20 lb propane is around 5 hours, this may vary depending on the load, size of the generator, and other factors. 

30 lb

Generators less than 5 W usually use 30 lb propane tanks that can averagely run for 7 hours. This time too shall vary with the generator size and the load of power on the generator.

40 lb/5 gallons

The ideal fuel capacity for generators between 6 – 8 kW is 40 lb/ 5 gallons. The average propane generator run time with this amount of fuel is estimated to be around 8 hours. 

100 lb

Generators of 9 – 11 kW usually use 100 lb propane tanks. These generators are mainly used as home power solutions. Depending on the usage, a generator of this size can run on 100 lb propane for over 17 hours on average.

100 gallons

How long will a generator run on propane of 100 gallons? Medium-sized generators of around 12 – 15 kW will run on 100 gallons for at least 36 hours. 

500 gallons

High power generators give an output of 18 – 22 kW. Hence, they require larger fuel tanks such as 500 gallons. These generators can store 400 gallons or less while using the rest. These generators can run up to 168 hours (6 and half days).

Propane Generator Fuel Consumption

On average, a generator will use 2 – 3 lb propane per hour. This time may slightly vary with the operating conditions of the generator. If you want to calculate how long will a generator run on propane, you can use the formula given below to figure out the estimation.

The total amount of Propane used in an hour in gallons=Watts/3000×0.65

The above equation can be derived as indicated below with the following assumptions and calculations.


  • The fuel value of Propane is 92000 BTU
  • The weight of every gallon of Propane is 4.2 pounds


BTU=Calculated Horsepower×10,000

Gallons of Propane=BTU/92,000

Considering a generator of 3000 watts, you will get 6 horsepower. Then the resulting BTU will be 60,000 BTU hourly. With the final step of the calculation, you will see that the gallons of propane equal 0.65. Combining all these equations, the initial equation written at the beginning can be obtained.

The Efficiency of Propane Generators

Propane is considered a favorable fuel for generators as it emits lesser toxic fumes. Thus, it leaves behind a less damaging carbon footprint. Hence, propane generators are a practical solution for alternative power sources. Propane is also more efficient as it is a more pure fuel than gasoline and has a longer combustion time. If you need to learn more about the differences, refer to Propane vs Gas Generators

What Size of Propane Tank Would Suit Residential Needs?

Selecting the ideal propane tank for your generator is an important task. This should be done based on the size and the running time of the generator. If you need to know more about the propane consumption per hour, you can refer to the related manufacturer details. Considering residential applications, a 20 lb propane tank would be enough for basic needs such as powering up a gas stove, furnace, and other small appliances. Although this may help your electricity needs for around 5 hours, you would need to have more propane for longer periods. 

Frequently Asked Questions

How Long Will a Generator Run on Propane?

How long will a generator run on a 20 lb propane tank?

On average, a generator will run for around 5 hours on a 20 lb propane tank. This may change depending on other conditions of the generator’s operation.

Do I need to purchase a generator?

You may need to purchase a generator if you face frequent power outages in your area, which hinders your daily tasks. Having a backup power source will help reduce the stress and move on with your routine without disturbances. 

Which is cheaper; a propane generator or a gas generator?

In terms of mere cost, propane generators may be a little less efficient than gas generators. But propane is cheaper than gasoline or diesel. Considering the environmental effects and cleaner-burning, propane is considered to be a wise choice.

How often should you operate your generator?

It is recommended to run your generator for a few minutes every four weeks. This will ensure proper oil circulation to keep the components lubricated. Make sure to add a load by plugging in some electrical appliances when running the generator. If not, the alternator could be damaged due to running for a long time without a load. 


The propane generator run time on a 20 lb tank will be around 5 hours or more. Therefore, having an adequate supply of fuel for your generator will help face extreme power outages, especially during seasons of adverse weather where power failures are common. Being a generator owner, you should also make sure to keep your generator safe from the rain while operating. This will not only protect the machinery but also remove potential risks of electrocution. 

Are propane generators quiet? This is a major concern among people who are looking for a new generator. Knowing these important facts will help in choosing the ideal type of generator for your power requirements in blackouts.