# How Many Gallons In a 100 lb Propane Tank (Propane Tank Size)

Have you ever asked yourself or your friend how many gallons are in a 100 lb propane tank? Well, you are at the perfect place to find the answer to such a question.

A 100 lb propane tank holds 100 lb of propane, right? Well, not exactly.

It can be a bit confusing that propane tanks are typically labeled by weight, not gallons. As a result, a 100 lb propane tank does not carry 100 gallons of propane. You have to do some math in order to figure out how many gallons any propane tank carries.

To put it simply, on average you have 0.236 gallons = 1 pound of propane.

So, how many gallons (gal) are in a 100 lb propane tank? A 100 lb propane tank has the capacity to hold about 23.6 gallons of propane, and it weighs 170 lb when full. This information is useful whenever you are selecting and maintaining your propane tank. In reality, a 100-lb propane tank is about 80% full, so the most you can put in is 20 gallons.

To learn more about the maximum capacity in gallons of a 100 lb propane tank, keep reading. This guide fully explains the math and conversion so you can figure out how many gallons are in your propane tank, whether it is 100 lb or another size.

## How Many Gallons Are In A 100 lb Propane Tank?

A 100 lb propane tank holds 23.6 gallons of propane. If the 100 lb tank is filled up with 23.4 gallons of propane, the entire container will weigh about 170 lb in total.

### How Can You Calculate How Many Gallons Are In A Propane Tank?

We did not just pull 23.6 gallons out of the blue. Instead, you can use a formula to figure out how many gallons will be in your propane tank.

Whenever the propane tank is set at 60 degrees Fahrenheit, which is the ideal temperature, 1 lb of propane is equal to 0.236 gallons. You can use this information to figure out how many gallons are in your propane tank.

In the case of a 100 lb tank, all you need to do is multiply 0.236 gallons by 100 lb. When you do this math, you will find that there are 23.6 gallons in the 100 lb propane tank.

0.236 gallons X 100 lb = 23.6 gallons

You can do this for any size tank. All you will need to do is change out 100 lb by however many lb are in the tank if you’re dealing with. For example, let’s say you need to figure out the capacity in gallons of a 50 lb tank. Multiply 0.236 gallons by 50 lb. You will find that that tank holds 11.8 gallons.

0.236 gallons X 50 lb = 11.8 gallons

## It’s Not An Exact Science

All that being said, keep in mind that estimating how many gallons are in a propane tank is not an exact science. Different factors impact how much propane is in an individual tank. 23.6 gallons is the number of gallons within a 100 lb tank in ideal situations.

Depending on your environment and factors, there may be more or less in the tank.

## Factors That Impact How Much Propane A Tank Can Hold

What factors impact how much propane a tank can hold in gallons? Here are the main factors you need to consider:

### Temperature

Whenever we calculated how many gallons are in a 100 lb tank, we used calculations based on propane tanks kept at 60 degrees Fahrenheit. If you change the temperature of the tank, you will also change the pressure within the tank.

If the temperature goes above 60 degrees Fahrenheit, the molecules will become more spread out, which means less propane can fit inside the tank at one time. This isn’t that big of a deal if you aren’t at the maximum capacity. However, the tank can explode if the temperature is increased, and the tank is already at its maximum capacity.

Conversely, dropping the temperature will drop the pressure as well. If the pressure drops enough in the tank, the tank will stop working altogether. Even if the tank works at a lower pressure, you will have to refill the tank more frequently.

In other words, only expect the tank to have a capacity of 23.6 gallons if the tank is maintained at a 60 degree Fahrenheit constant.

### Water Capacity

Every tank will have a water capacity stamped on the collar. This number tells you the total mass of liquid in lb that the individual cylinder can hold if it becomes filled with water. Propane tanks can hold about 42% of the water capacity in propane.

Let’s say that your tank has a water capacity of 240. Multiply 240 by 0.42. You find that that tank can actually hold 100.8 lb of propane, not just 100 lb. As a result, this tank can hold slightly more than a standard 100 lb tank since this tank has a slightly higher capacity.

Obviously, 0.8 lb is not that big of a difference. Even so, this factor can make a huge difference in certain tanks.

Looking at the water capacity can give you a better idea of how many lb your tank can hold so that you can have a more accurate estimation of how many gallons it can hold.

## How Much Does A 100 lb Propane Tank Weigh When Full?

Because the propane tank can hold 100 lb, you might assume that a 100 lb propane tank weighs 100 lb when full. This is not the case. The 100 lb refers to the weight of the propane, not the propane and the tank together.

In order to get the actual answer to how much a 100 lb propane tank weighs, you have to add the 100 lb of the propane to the weight of the tank. The exact weight of the tank will vary based on the manufacturer and other factors. That being said, most propane tanks weigh around 70 lb.

If your propane tank weighs 70 lb when empty, all you need to do is add 100 and 70. That tells you that a 100 lb propane tank weighs about 170 lb when full.

## How Long Will A 100 lb Propane Tank Last?

Unfortunately, there’s no one size fits all answer for how long a 100 lb propane tank will last. How long your propane tank lasts ultimately depends on how much you use it.

If you use it all day, it won’t last as long as a tank that is only used for half a day.

You also have to consider the BTU of the appliance you are using the propane tank on. BTU stands for British thermal unit.

The higher the BTU, the higher the power of your appliance. For example, fireplaces can be measured in BTUs. The higher the BTU, the more powerful the fireplace is at warming the area.

If you have a 100 lb propane tank and are using it to power your 20,000 BTU fireplace, how long you used the fireplace will determine how long the propane will last.

If you use the fireplace constantly, your propane will only last about 4.5 days. However, that tank will last up to 9 days if you only use the fireplace 12 hours out of the day.

So, you’ll need to figure out the BTU and estimated time of usage if you want to figure out how long a 100 lb propane tank will last.

There simply is no one quick answer to this question.

## Propane Tank Capacity Comparison

There are several different sized propane tanks. It’s important to select the right propane tank capacity based on your intended needs. Here’s a look at the most common propane tank capacities.

Here’s a chart that explains the dimensions and tares weight of many propane tank sizes:

## What Sized Propane Tank Is Right For Me?

What size propane tank is right for you ultimately depends on your needs. A 100 lb propane tank is really good for individual small indoor appliances. For example, a 100 lb tank is frequently used to heat up a sole fireplace or a grill.

If you are looking for a propane tank for smaller jobs, you probably do not need a 100 lb tank. You might be able to get away with a 25 or 50 lb tank instead.

In contrast, you will want to upgrade to a 500, 750, or 1000 lb propane tank if you need it for intense residential or commercial needs.

## Final Thoughts

You can calculate how many gallons are in your propane tank. Whenever the constant temperature is 60 degrees, 1 lb of propane is equivalent to 0.236 gallons.

If you multiply the lb by the gallons, you will be able to find out how many gallons are in your propane tank.

When looking at a 100 lb propane tank specifically, you will multiply 0.236 gallons by 100 lb. Using this math, you’ll find that there are 23.6 gallons of propane in a 100 lb propane tank.

Keep in mind that this capacity is based on a constant temperature of 60 degrees Fahrenheit.

The great news about propane tank capacity is that you can use the same math on any propane tank.

Whether you are dealing with a 20 lb tank or a 1000 lb tank, you will be able to find out how many gallons the tank can hold using the formula above. Good luck!