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How Many Gallons Are in a Propane Tank? Types & Sizes

chained LPG stank with stovetop

Figuring out how many gallons your propane tank can hold can be a challenge. It is confusing because some propane tanks are measured in gallons, like a gas tank, while others are measured in weight. The most common propane tank is measured in weight (20 lbs), while tanks commonly used to heat homes are measured in gallons. What gives? How many gallons are there in a typical propane tank? In short: 20lbs tank holds 4.5 gallons.

This overview will go over how many gallons average propane tanks can hold, the average relative sizes of propane tanks, and the dimensions of propane tanks. By the end, you will have a good idea of how many gallons your propane tank can hold and how big certain propane tanks can get.

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The Common Propane Tank

The most common propane tank size typically used by homeowners and regular people is 20 pounds. The 20-pound propane tanks are often stacked up in front of your local grocery store or hardware store. These propane tanks are used to power everything from gas grills to forklifts.

A 20-pound propane tank holds 4.5 gallons of propane. Some people will say they hold 4 gallons, while others will say they hold 5 gallons. When talking about propane, it is better to err on the side of caution and use four gallons because propane tanks are rarely filled to complete capacity. Many HVAC professionals will assume that a 20-pound propane tank has 4 gallons of propane rather than 5 gallons, but it is not uncommon to see 20-pound tanks marked as 5-gallon tanks.

The 20-pound or 4-gallon tank is the average size for a propane tank, but there are other various sizes. Anything smaller than a 4-gallon tank is considered small, while anything larger is typically considered a large or above-average tank. Here is a basic breakdown of how large propane tanks are compared to each other.

Relative Tank Size Gallons
Small 0.5–3
Average 4–5
Above Average 5–25
Large 25–100
Extra Large 250+
pink propane LPG tanks
Photo Credit By: Mufid Majnun, Unsplash

Gallons Per Propane Tank

Now that we have covered the basic propane tank, what about the others? Propane tanks come in various sizes, from tiny 1-pound cylinders up to massive 1,000-gallon tubs. More confusingly, sometimes propane tanks are measured in pounds, and other times they are measured in gallons. To make it simple, we have broken down the most common propane tank sizes and labeled them in gallons and pounds. Generally, every 5 pounds holds 1 gallon, but the math is not exact.

Gallons Per Propane Tank

Size In Weight Size In Gallons
3 lbs. 1 gallon
20 lbs. 4 gallons
100 lbs. 25 gallons
500 lbs. 100 gallons
1,250 lbs. 250 gallons
2,500 lbs. 500 gallons

It is important to know how many gallons come in a propane tank, even if measured in pounds, because many filling stations will charge you by the gallon to refill them. It won’t be good to bring in a 100-pound tank to get refilled if you don’t know how many gallons it holds. You will be stuck with a bill that you have no clue about.

propane gas tanks
Photo Credit By: 652234, Pixabay

Propane Tank Sizes

In addition to knowing how many gallons your propane tank holds, it is also a good idea to know what size the propane tank is, including its empty weight. The empty weight, or tare weight, of a propane tank can be used to measure how much propane is left in the tank (which can then be converted into gallons for those who wish to know.)

Here are the dimensions and weights for common propane tank sizes from 1-gallon to 500-gallon tanks.

Common Propane Tank Sizes

Tank Size Dimensions L x W x H  (Inches) Empty Weight
1 gallon 12 x 7.6 x 7.6 5.9 lbs.
5 pounds 12 x 8 x 8 6.7 lbs.
4 gallons 18 x 11.6 x 11.6 12.7 lbs.
20 pounds 18 x 12 x 12 13.5 lbs.
20 gallons 48 x 12.5 x 12.5 50 lbs.
100 pounds 48 x 14.5 x 14.5 67 lbs.
250 gallons 92 x 30 x 30 483 lbs.
500 gallons 120 x 37 x 37 950 lbs.

As you can see, some propane tanks get extremely large and heavy. Some of these numbers can also be misleading, so it is important to know whether you are looking at a 20-pound propane tank or a 20-gallon propane tank. A 20-gallon propane tank is much larger than a 20-pound propane tank. The 20-gallon tank weighs 50 pounds and measures 4 feet long compared to just 1.5 feet for the 20-pound tank.

Knowing the empty weight and dimensions and the gallons per tank is important to consider before ordering, refilling, or transporting large propane tanks.

two propane tanks in hardware
Photo Credit By: PxHere

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Pounds vs. Gallons

Propane tanks are measured in pounds and gallons. Typically, small tanks are measured in pounds for a couple of reasons. First, it tells a person roughly how much it weighs since they are often loaded and carried by hand. Secondly, a person can weigh a propane tank and find out exactly how much propane is left inside using a scale and the tare weight. Small tanks that are movable by hand are often measured in pounds rather than gallons.

Large stationary tanks or underground tanks are usually measured in gallons. Permanent tanks are refilled by a propane truck, and the owner is usually billed in gallons. Having a 250-gallon tank labeled that way instead of a 1,200-pound tank helps the owner know how much they can expect to be charged for a refill since propane is not sold in bulk by the pound.

Also, remember that a tank’s empty weight and full weight are very different. The empty weight tells you how much the tank weighs without any propane. This is useful for measuring, moving, and storage purposes. However, the full weight is much heavier than the empty weight. For example, the empty weight of a 20-pound tank is roughly 13 pounds. One gallon of propane weighs roughly 4 pounds, so a full tank can be much heavier than you expect.

On the other hand, small tanks are usually swapped out and carried to a store by hand. Large stationery, buried, or immobile propane tanks will most often be labeled in gallons rather than pounds because no one is lifting the tanks.

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The typical propane tank holds between 4 and 5 gallons of propane, but there are numerous sizes of propane tanks that can hold anywhere from a single gallon to hundreds of gallons. Knowing how many gallons your propane tank holds can help you budget for the future and gauge the relative size of the tank for moving or storage purposes. Typically, small tanks are measured in pounds, but large tanks are almost exclusively measured in gallons. This information will help you quickly determine exactly how many gallons your propane tank can hold.

Related Read: Can Propane Tanks Explode? How Likely Is It?

Featured Image Credit: Mac Kenzie, Pixabay


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