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How Many Gallons Are in a Propane Tank? (Standard Size Chart)

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 (20lbs), 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 lbs. The 20 lb. propane tanks are the ones you often see 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 lb. propane tank holds 4.5 gallons of propane. Some people will say that they hold 4 gallons, while other people 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 lb. propane tank has 4 gallons of propane rather than 5 gallons, but it is not uncommon to see 20 lb. tanks marked as 5-gallon tanks.

The 20 lb. 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 in comparison 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
Image Credit: 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 one-pound cylinders all the way up to massive 1000-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 five pounds holds one 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 it is measured in pounds because many filling stations will charge you by the gallon to refill them. It won’t do you any good to bring in a 100 lb. 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
Image Credit: 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 itself 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, say, 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, as well as the gallons per tank, is important to consider before ordering, refilling, or transporting large propane tanks.

two propane tanks in hardware
Image Credit: PxHere

Pounds vs. Gallons

Propane tanks are measured in both pounds and gallons. Typically, small tanks are measured in pounds for a couple of reasons. One, it tells a person roughly how much it weighs since they are often loaded and carried by hand. Two, 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 1,200lb 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 can be much heavier than the empty weight. For example, the empty weight of a 20lb tank is roughly 13lbs. One gallon of propane weighs roughly four pounds, so a full tank can be much heavier than you expect.

Small tanks, on the other hand, 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 in pounds because no one is lifting the tanks.

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The typical propane tank holds between four and five 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 figure out 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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