# HOW MUCH DOES A GALLON OF PROPANE WEIGH? (Propane Tank Math)

Are you wondering HOW MUCH DOES A GALLON OF PROPANE WEIGH?

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?

## HOW MUCH DOES A GALLON OF PROPANE WEIGH?

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

Liquid propane is measured in gallons, while gas propane is measured in pounds.

The most common way to measure propane is by the gallon. You can also measure it in pounds, where one gallon of propane weighs 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?

You can use a propane tank gauge or scale to measure the weight of a propane tank.

Magnetic Gas Level Indicator

Propane Tank Gauge Level Indicator

## 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. 

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.

## How much does an empty propane tank weigh?

An empty propane tank weight is usually referred to as the tare weight. You can easily find the TW, i.e., the Tare Weight of the propane on the steel collar of the tank.

Moreover, if you want to know the remaining gas in the tank, subtract the empty tank weight from the total, and here you go!

As cleared already, the weight of empty propane tanks is different for different sizes. Let’s have a look at the chart indicating the weight of propane tanks with different sizes when it’s empty:

For 100lbs propane tank:

The weight of empty propane tank=  70 lbs

Weight of a full tank=  170lbs

Capacity to be filled= 170-70 lbs = 100 lbs.

Let’s take another example for a 30lbs propane tank:

Empty propane tank weight= 25lbs

Weight of total propane tank= 55lbs

Capacity of gas= 55-25 lbs= 30lbs

In short, the weight of a full propane tank is the combination of empty tanks weight and the capacity of the gas that can be filled in the tank.

Propane gas to be filled in the tank =Weight of full tank – Weight of empty propane tank

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.

## How much does a 100lb propane tank weigh?

Propane weighs 4.24 lbs per gallon so 100 lb capacity would hold 23.6 gallons.

The full weight of a 100lb propane tank is 165 pounds.

When empty 100lb propane tank weighs 67 pounds and has a propane capacity of 98lb. It can generate 10,000 BTU/h for 36 hours.

## FAQs

### How much does a pound of propane weigh?

The density of propane is taken as 493 gm/Ltr at 25°C.
While1 Pound = 453.6 gm.
So the volume of 1 Pound propane = 453.6/493= 0.92 Ltr

1 Pound of propane will be 0.92 Litter in volume at 25°C.
Please note that propane expands at the rate of 1.5 % with the increase of 10°F temperature.

### How much does one gallon of propane weigh?

One gallon of propane weighs 4.24 lb.