The weight of the propane depends on the temperature and pressure. The weight of one gallon of propane at room temperature (77 F) and atmospheric pressure is about 4.2 pounds or 1.9 kilograms. Propane has a density of 0.493 g/cm3 at standard temperature and pressure.

Propane is a hydrocarbon gas that is used as a fuel. It is widely used in heating and cooking.

In this article, we’re going to discuss how much does a propane tank weigh, water capacity, propane density, and how to calculate the propane weight per gallon. By using these parameters, you can easily illustrate how much does a gallon of propane weigh in pounds?


Propane is a highly flammable gas that is stored in tanks under pressure and at a certain temperature.

The most common way to measure propane is by the gallon. You can also measure it in pounds, where one gallon equals four pounds (4.2lbs).

The propane weight per gallon is dependent on temperature and pressure.

To find out how to check the propane level in a tank, check out this article here.

Where to store a propane tank?

How much does propane weigh?The density of propane

According to Wiki, “The density of propane gas at 25 °C (77 °F) is 1.808 kg/m3, about 1.5x the density of air at the same temperature. The density of liquid propane at 25 °C (77 °F) is 0.493 g/cm3, which is equivalent to 4.11 pounds per U.S. liquid gallon or 493 g/L. [25]

At room temperature (77°F), LPG has a density of 4.11 lb/gallon, which is dependent on temperature. As the temp rises, gas becomes less dense.

We know that at high temperatures, gases (even liquidated one’s like liquid propane) expand, which results in decreasing the density of propane and increasing the volume and pressure of propane inside the propane tank.

When propane is subjected to lower temperatures, the “density” of propane increases while propane volume and pressure decrease.

According to the wiki, Propane expands at 1.5% per 10 °F”. Thus, the density of liquid propane at 15.6 °C (60 °F) is approximately 4.2 pounds per gallon (504 g/L).

So Propane weight per gallon varies with a change in the temperature of atmospheric conditions.

How much does a propane tank weigh?- Tare weight of propane tank:

Every propane cylinder has some information that is stamped into the guarding shroud on the top.

Stamped on the handle of the propane tank is “TW” followed by a number.

Propane tanks have a “tare weight” also known as “TW” printed on their collar, which is the weight of the tank when it’s empty. So in order to find “how much does an empty propane tank weigh?” simply look at the Tare weight of the propane tank.

Typically, the propane tank we use at home for bbq, grilling, or cooking is 17 or 18 pounds.

To figure out how much a full 20 lb propane tank weighs, simply add 20 pounds to the tare weight. So if your propane tank has a tare weight of 17, then a full propane tank weight should be about 37 pounds.

Water capacity of a propane tank

The propane cylinder has water capacity markings and that will be stamped as “WC” followed by a number.

The water capacity is the pounds of water the tank will hold if you’re to open that cylinder up and fill it right to the top with water.

Now we need to consider a couple of things.

First of all, we’re only allowed to fill the tank up to 80% full.

Second water weighs differently than liquid propane.

Liquid propane is about half the weight of water. Now at this point, we could do a bunch of irritating math with specific gravities and all that, or we could just do with the propane storage and handling code tells us to do.

So let’s do an example together.


I found a propane cylinder here, and it has a WC stamping of 47.6

Water density = 1 g/cm3

The density of propane liquid is 0.493 g/cm³ at 25 °C (77 °F) or 4.24 pounds per US gallon.

To fill the propane by weight, multiply the Water capacity ‘WC’ by 42%

That is 47.6*42% = 19.992 we’ll call it approx 20 pounds.

So what that means is when we filled the propane we will fill up to its 80% capacity like we are supposed to. That is 20 pounds of propane.

For portable tanks, the water capacity is listed on the collar in (lbs or gallons). Multiply this value by 0.42 to get propane capacity in pounds or gallons (according to how the water capacity is listed in pounds or gallons). A 20 lb cylinder holds 20 lbs of propane at 80% capacity and that applies up through 100 lb cylinder sizes.

Now the next thing I want to point out is that tare weight and we can see that in the stamping it looks like TW18.

What this means is if we had that propane cylinder completely empty, it would weigh 18 pounds on a scale. So what we can do is take my propane capacity and add it to the tare weight. We would easily find out how much a propane cylinder weighs when it’s filled up to 80% full.

So 20 pounds + 18 pounds = 38 pounds

Date on a propane tank:

There’s also a month and year provided on the propane tank collar that indicates the date it was manufactured.

If you buy a 20 lb propane tank, it could have 12 years left of usable life. Re-certification will only give the tank an additional 5 years before it has to be re-certified again. Re-certifying tanks may be more expensive and time-consuming than purchasing a new tank.

Propane tanks that come straight from the manufacturer can not be filled all the way. A lot of times, there is air in these tanks, which means that you need to purge it before you can use it.

Propane Tank Weight Chart

Below, you will find the propane tank weight chart for common propane sizes to help you choose the one that best suits your needs.

Propane tank20 Pound Propane Tank100 Pound Propane Tank100 Gallon Propane Tank250 Gallon Propane Tank500 Gallon Propane Tank
Propane Content19.74 Pounds98 Pounds418 Pounds1048 Pounds2098 Pounds
Empty Tank Weight17 pounds67 Pounds212 pounds483 Pounds949 Pounds
Full Tank Weight37 Pounds165 pounds630 Pounds1531 Pounds3047 Pounds
Propane Tank BTU Content344,470 BTUs1,722,350 BTUs7,320,000 BTUs18,300,000 BTUs45,750,000BTUs
Can Generate 10,000 BTU/h 36 Hours7 Days32 Days78 Days193 Days
Propane Tank Weight Chart

Thank you for reading this article. Hopefully, after reading this article, you can figure out how much does propane different-sized tanks hold! If you have any questions, feel free to leave a comment below.

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