How Much Does a Propane Tank Weigh? (2024)

So, how much propane tanks weigh you wonder? Well, one gallon of propane weighs 4.2 pounds. “Full” 20 lb propane cylinders should have 4.7 gallons of propane in them. The most common way to measure a full propane tank is by gallons. It can also be measured by pounds (one gallon = 4.2 lbs). When measured in gallons, a meter at the pump is used to determine the amount of propane that has been filled into a propane tank. When measured in pounds, the tare (empty starting) propane tank weight must be known first.

Important Facts You Should Know About Your Tank

All propane tanks have a “tare weight” or “T.W.” stamped on the collar of the liquid propane tank. Tare weight is the weight of an empty propane. For a grill-sized tank you simply calculate the tare weight + 20 lbs, and that’s how much propane cylinders (a full propane tank) should weigh when it’s full. Almost every 20 lb propane cylinder has a tare weight of +/- 17 pounds when completely empty.This means a full propane tank weight (tare weight + propane weight) is about 37 pounds.

There is also a month and year on the collar indicating the date the propane tank was made. For 20 lb portable propane tanks, you have 12 years from the manufacture date before the tank must be re-certified with a new date stamped on it. The re-certification only adds 5 years before having to re-certify again. The cost and inconvenience of re-certifying almost always outweigh the price of a new propane cylinder.

Purging the Tanks

Brand-new propane tanks may come with air inside and need to be “purged” before the first fill. Some newer propane tanks, like Bernzomatic, will have a sticker on them saying they don’t need to be purged within 6 months of the manufacture date.

Purging requires a special adapter to allow a small amount of propane in. The tank pressure then pushes air out of a one-way bleeder valve. Purging may add another $3-4 dollars to a new propane tank, though some places don’t charge, especially if you buy the portable propane tank from them.

• 1 gallon of propane weighs 4.2 pounds

• A “full” 20 lb cylinder (a full propane tank) should have 4.7 gallon of propane in it.

These “20 lb” tanks with corresponding water capacity are designed to take up to 20 pounds of propane. You may get a pound or 2 less, depending on the temperature of the propane tank and surrounding air when the propane cylinder is filled. Cooler = more propane in, hotter = less in. Tanks can actually fit another 20% in the tank, but that extra space is designed for expansion as the temperature rises.

In very cold winter situations, like those in Canada, there may be more concerns/rules about filling a propane tank to a complete 20 lbs. This is because if you leave a propane cylinder outside in very cold temps, fill the propane tank when it’s cold, and then bring it into a hot basem*nt/garage for a space heater, the gas will expand as the propane cylinder warms – as the liquid form turns into a gas form. With enough of a temperature increase, the tank’s pressure relief valve will release a bit of gas. This is less of an issue if the relief valve is bleeding to outside air.

How Much Does A Propane Tank Weigh When Full?

Below is a chart of all the propane tank sizes with their corresponding propane tank weight when full. For this section please go into detail on the 80% rule for why propane tanks cannot drop below 20% full water capacity for safety reasons. This is the first fact to know before you ask how much does a full propane tank weighs. This chart also assumes the propane tank is 100% empty, so for owners weighing a propane tank themselves, it typically will be a higher weight than listed due to the pressure of a propane tank dropping when it hits 20% and under.
Also please be sure to link our article on how to tell when a propane tank is empty.

How Much Does A Propane Tank Weigh When Empty?

Below is a chart of all the propane tank sizes with their corresponding weight when full. For this section please go into detail on the 80% rule for why tanks are not filled up to 100% capacity. 1 Gallon of propane weighs 4.24 pounds.

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