What Sizes of Propane Tanks Are Available for Generators?

Last Updated: August 8, 2022
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Many propane-powered generators are available on the market right now. You can also get conversion kits to transform your diesel generator to propane or natural gas. Propane is much cheaper to store and more durable than oil, many people want to use it as a fuel for their generators. If you’re going to use propane as a generator fuel, you’ll need to figure out what size tank you’ll need.

Why Is It Important to Pick the Right Size Propane Tank?

The size of your propane tank is an important first step in setting up your propane generator. You actually spent a lot of time deciding on the best generator for your house. You’ve researched, calculated the size you’d like based on how many appliances you’d like to operate, chosen which business to go with, and what basic model. The next move, on the other hand, is a little more difficult.

If you’re putting a generator in a house that doesn’t already have one, you’ll still need a power supply so you won’t be able to operate the system otherwise.

In order to run your generator properly, the tank you are installing must be of the correct size. Having one that’s too small won’t have enough gasoline for your needs, and one that’s too big will make you pay more than you need.

A propane fuel tank can be placed above ground or below ground. In certain cases a nearby propane provider rents or leases the fuel tank to the householder.

The decision between an above-ground and underground propane storage tank is largely based on three factors: the size tank you need (underground tanks will be bigger and have a higher capacity), the look you want for your property, and whether or not installing an underground tank is legal in your town and on your property. A certified propane tank manufacturer can inform you whether you can use an underground propane tank.

Two basic varieties are available in the above ground propane tanks: horizontal tanks and vertical cylinders. Horizontal propane tanks are large, high-capacity containers that are typically used in homes where propane is the primary source of heat. You won’t need too many propane deliveries because they store more propane, which is a major plus in places where the weather is volatile. Vertical propane cylinders are usually smaller so that they can be positioned outside the view of a house or next to a property line.

How to Know Which Size of Propane Tank You Need?

It depends on the generator size as well as the amount of time you want to run it.

You’ll need to figure out how much propane the generator needs every hour now that you’ve determined the size generator you want to add (or already have). Most propane generators come with paperwork detailing how many gallons of propane it takes every hour to generate the amount of energy it generates. You may also contact the manufacturer to collect this information.

Then you have to try to figure out how much power you want to use and how many hours you expect the generator can work. If you just want to use your generator as a backup power source, the most you can do is come up with a rough estimate. However, if you think you’re going to use it more extensively, you can try to calculate the number as accurately as possible.

It is easy to calculate how much fuel you need with these two figures identified. Multiply your generator’s fuel consumption per hour by the hour you expect to use the generator.

For most home use, we suggest either a 120-gallon tank for fast breaks (1-2 days) or a 500-gallon tank for longer periods (8-10 days).

Table 1 shows the most common sizes for below-ground residential LPG tanks,* while Table 2 shows the most common sizes for residential above-ground LPG tanks*.

*According to the manufacturer, the exact physical dimensions of the propane tanks can differ and use these as guidance only.

Table 1 – Common Sizes of Above Ground Propane Tanks Available for Generators

500 Gallon250 Gallon150 Gallon
Empty Weight950 lbs485 lbs320 lbs

Table 2 – Common Sizes of Below Ground Propane Tanks Available for Generators

1000 Gallon500 Gallon250 Gallon

The size of the tank is proportional to the length of time you want to be certain that you’ll have enough fuel to run your backup generator if your electricity goes out. 

Calculation of fuel for hours of operation is relatively easy. Each generator manufacturer shall determine the amount of fuel consumed by a certain generator engine under half and/or full load. It is only appropriate for you to calculate the load and to do some simple math.

In most cases, calculating fuel consumption for the desired time at half-load is an acceptable approximation. It would be very rare for a backup generator to run continuously at full load for three or five days.

Although the propane generators simply burn gas (cubic feet per hour) not fuel, the tanks are listed for liquid calculation. In certain circumstances, however, you will see that the maker of the standby generator has indicated fuel consumption in cubic feet per hour.


What Size Generator Should I Buy?

A 22 kw generator will support a house of 3-4,000 square feet. The Hvac systems and the washer or oven would be running at the same time. Ensure that the propane lasts much longer and more reliably by selecting the usage of the equipment when the generator is in service. Another choice is to add a bigger generator that will power more of your house’s electrical systems.

How Long Will I Have Power with Propane?

Home backup generators usually range in size from 7 to 20 kilowatts (kW). The 7 kW generator is strong enough to operate only vital systems at home. That includes heating systems, pumping, refrigerators, and some lighting. A person will need to switch to a 15 kW system at least to enjoy his house, just as with regular electricity.

On a 100 gallon tank on a max load, a 7kW generator will run about 66 hours and a 12kW generator for 36 hours.If the generator is running between 25% and 75% of its capacity and the fuel supply lasts even longer.


Whatever the portable generator’s requirements and use, you’ll be able to find a propane tank that meets them. Both propane tanks available for generators are refillable and can be filled at a propane filling station or refilled by the propane service company if they are larger unmovable tanks.

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I am a mechanical engineer with years of experience working on Internal combustion engine and fixing electrical and mechanical systems, generators, transfer switches, and equipment related to storm water and sewage pumping stations.