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How Long Will the Generator Run on Propane (20, 30, 40 Lbs)?

Propane is a popular type of fuel that is used to run generators. It is affordable and widely available for generator owners in the market.

It is a common question about how long will a generator run on propane. Let us help you get some insight about the use of propane in generators and also look into the working mechanism of it as well.

How long will the generator run on propane?

The generator will run for fives hours on a 20lb propane tank. The time will vary based on the capacity of the propane tank that you will use. But 20lb propane tanks are popular in the United States. Thus, it can be said to be the average propane tank size though it may vary based on usage & load.

Propane has a lower burning index which is known as BTU. Therefore, propane is slow-burning fuel.

This results in efficient fuel consumption compared with other fuel types. Propane can run a generator for a longer period of time than any other fuel type. Thus, it is popular among generator owners.

You may purchase propane tanks of various sizes as per your requirements. Usually, a generator may consume around 2 – 3 lb of propane per hour.

Let us look into some popularly used capacities of tanks for storing propane and understand how much time your generator may run on it:

20 lb:

20 lb capacity of propane is widely used and easily available in the market. It is mostly used for portable home generators of 1 – 3 kW. 20 lb can run your generator for five hours on average depending on your generator’s size and load on it.

30 lb:

30 lb is an ideal propane capacity for generators with a size less than 5 kW. 30lb of propane can run a generator for 7 hours on average. The time varies based on the generator size and current load on the generator.

40 lb/5 gallons:

Generators between 6 – 8 kW use 40 lb / 5-gallon propane as fuel capacity. Though, 40 lb / 5 gallons can be used for lesser or above-sized generators than the ones are highlighted. But the highlighted range of generators is ideal for this capacity of propane.

Based on load and size, 40 lb / 5 gallons can run a generator for 8 hours on average.

100 lb:

Medium-sized generators use 100 lb propane tanks. Here, medium-sized generators are 9 – 11 kW generators. These are often used for entire home power solutions. 100 lb can run a generator for 17 hours on average depending on usage and size of the generator.

100 gallons:

For medium size generators, 100 lb is the proper amount of propane. 12 – 15 kW generators are known as medium-sized generators.

100 lb of propane can run a medium-sized generator for 36 hours at least. This time depends on the current load of the generator and its size.

500 gallons:

High power generators, like 18 – 22 kW generators, require bigger fuel tanks. 500 gallons of propane will be appropriate for these generator sizes. Out of the 500 gallons, it has the capacity to store 400 gallons more or less.

500 gallons will run your generator for an average of 6 and a half days, which is 168 hours in time. This is an ideal size for a high-power generator.

Generator Brand How Long Will They Run on Propane
Duromax generator5 hours
Westinghouse generator6.5 hours
Generac generator5.5 hours
Firman generator6 hours
Champion generator5.5 hours
Honda generator6 hours

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

It is cheaper to run a generator on gas than propane. Gas is cheaper per gallon compared to propane. Therefore, gas is a cheaper option for you to run your generator.

Let’s analyze the facts using real math. According to the recent information, 1 gallon of gas will cost you 0.90 $, and propane will cost you 2.41 $. Therefore, gas is cheaper than propane. This means gas is a cheaper choice to run a generator rather than propane.

Will a generator run longer on gas or propane?

A generator will run longer on propane compared to gas. The same propane will run your generator three times more compared to the same amount of gas.

Though this depends on the load on the generator and the size of it as well. To understand this more properly, let’s look into some numbers. If you take 1 gallon of gas and propane individually in two generators, the generator on propane runs for 32 hours.

Whereas, the generator on gas will run only for 10 hours or less. These numbers say clearly that propane can run your generator for a long time compared to gas.

Propane vs. Natural Gas Generator

There are the following differences among propane and natural gas –

Fuel consumption:

Propane generators consume less compared to natural gas generators. A propane generator can run for 3 times more compared to a natural gas generator. Thus, propane generators are efficient compared to natural gas generators.

Electricity production:

Natural gas generators produce more electricity rather than propane generators. You can see that the running and starting power production of a natural gas generator is 20 – 30% more than a propane gas generator. Thus, natural gas generators produce more electricity.

Environment friendly:

Generators burn fuel to run its engine which exhausts carbon smoke in the environment. This means generators are a big reason behind environmental pollution causing temperature rise in the environment and many more.

Propane generators do not release any kind of smoke in the environment which is bad for the environment. But natural gas generators release bad smoke. Therefore, propane generators are environmentally friendly rather than natural gas generators.


Propane generators have a better lifespan compared to natural gas generators. As natural gas generators produce carbons, it slowly jams the engine and exhaust. Therefore, the generator gets damaged slowly.

Moreover, Propane generators have a lower BTU compared to natural gas generators. Due to the lower BTU, propane generators heat generator engines less compared to natural gas, providing a better lifespan.

Thus, propane gas generators last longer compared to natural gas generators.

How to calculate propane generator run time?

If you want to calculate the run time of a propane generator, you will have to get some information and then calculate then in a simple method. Let us discuss the method so that you can find out the run time of your propane generator:

Identify the fuel consumption per hour of your generator:

Every generator has a particular rate of propane consumption limit per hour. Check your manual or search the internet for the information. But it is generally said that about 18.37 lb or 2 gallons of fuel is consumed per hour.

Find out the size of your propane tank:

To find the size of the propane tank, you can find it simply at the body of the tank. For small generators, a 20 lb propane tank is commonly used.

Calculate the time:

Now you will just have to use the following method to calculate. If you are calculating using lb amount of fuel the formula will be: (Size of the propane tank in lb/fuel consumption per hour (lb).

The formula will be the same for gallons as well. You will just have to use values in gallons.

How much propane does a generator use per hour?

Different sizes of generators consume different amounts of propane. Besides the size of a generator, the load on a generator also varies the quantity of propane required per hour. 

Let us help you understand how much propane is required per hour for the following sizes of generators:

Generator Size Propane Usage
2000w generator2.44 lb
3400w generator2.27 lb
3500w generator2.28 lb
4000w generator2.28 lb
5000w generator2.55lb
6000w generator2.63lb
6500w generator2.65lb
7500w generator2.70lb
8000w generator2.74lb
9000w generator2.88lb
9500w generator2.91lb
10kw generator3 lb
12kw generator3.1 lb
22kw generator3.47 lb

How long can a propane generator run continuously?

A portable generator can run 140 – 210 hours continuously. Though the run time will vary based on the propane capacity of the tank and load on the generator. If you continuously provide the necessary propane to run, it will run for you the whole time you need.

As propane generators run on a low BTU limit, the engine can run for a longer time compared to a natural gas generator.

Final Thoughts

A propane tank generator will run for 5 – 6.5 hours depending on the amount of fuel given in the generator and load. The generator will run for a longer run time also if the necessary fuel is provided from time to time. Thus, a propane generator can be an ideal generator for home users.