How Many Gallons Of Propane In A Tank? 20 lb, 30 lb, 100 lb

Prices of propane are usually listed ‘per gallon’. If you have a 20 lb, 30 lb, or 100 lb propane tank you will obviously be interested in how many gallons of propane are needed to fill up the tank.

Converting this propane size in lb to gallons of propane is not all that easy. That’s why we have prepared 3 useful resources to help to figure out how many gallons are in different propane tanks:

1. Propane Tank lb To Gallons Calculator. Here you just insert the propane tank size (10 lb, 20 lb, 30 lb, 50 lb, 100 lb, and so on), and you will automatically get the result of how many gallons of propane you need to fill up the tank.
2. 20 lb, 30lb, 100 lb Examples. Because 20 lb, 30 lb, and 100 lb tanks are the most commonly used ones we present examples of how many gallons of propane in a 20 lb tank and how many gallons of propane in a 100 lb tank to illustrate how the calculation works.

   

3. All-Encompassing Propane Tank lb To Gallons Chart. Here we calculate how many gallons of propane go into any lb propane tank (from 1 lb propane bottle to big 500 lb propane tanks).

Namely, there are two reasons why figuring out how many gallons of propane do these tanks hold are a bit complex:

1. 80% max. capacity rule. Example: 20 lb tank holds only 16 lb of propane. This is because all propane tanks can only be filled up to 80% of their capacity. This is a safety precaution; propane can expand at higher temperatures and create too much outward pressure for a propane tank to hold. That’s why we leave 20% of the tank empty to alleviate that dangerous pressure build up.
2. Density of propane. When you are converting the mass of propane (lb) to the volume of propane (gallons), you need to know how much does a gallon of propane weigh (for lb to gal conversion). Namely, as we have pointed out in the article about how much a gallon of propane weigh here, the density of propane is 4.11 lb per gallon (at 77°F).

Using these two metrics, we have designed the calculator, solved 20 lb, 30 lb, and 100 lb examples, as well as completed the full 1 lb – 500 lb propane tank chart. Let’s start with the LPG lb tank to gallons of propane calculator you can use yourself, and follow up with specific examples and the all-encompassing chart:

Propane Tank Lbs To Gallons Calculator

Here is how you can use this calculator:

Let’s say you have a 50 lb propane tank. How many gallons of propane go into a 50 propane tank? Just slide the slider to ’50’ and you get the result: 50 lb propane tank holds 9.73 gallons of propane.

Let’s look at some examples to see how this calculation is made:

How Many Gallons Of Propane In A 20 Lb Tank? (Example 1)

Alright, let’s say you have an empty 20 lb propane tank and want to fill it to the max. How many gallons of propane do you need to fill a 20 lb propane tank?

We have to use those two rules we have used in the introduction.

Applying the 80% capacity rule: A 20 lb propane tank actually holds 16 lb of propane when completely full.

Applying the LPG density: We have to divide these 16 lbs of propane by 4.11 lb/gallon to get to gallons like this:

20 lb Tank Capacity In Gallons = 16 lb ÷ 4.11 lb/gallon = 3.89 Gallons

In short, a 20 lb propane tank holds 3.89 gallons of propane.

How Many Gallons Of Propane In A 30 Lb Tank? (Example 2)

Let’s say you have an empty 30 lb propane tank and want to fill it to the max. How many gallons of propane do you need to fill a 30 lb propane tank?

We have to use those two rules we have used in the introduction.

Applying the 80% capacity rule: A 30 lb propane tank actually holds 24 lb of propane when completely full.

Applying the LPG density: We have to divide these 24 lbs of propane by 4.11 lb/gallon to get to gallons like this:

30 lb Tank Capacity In Gallons = 24 lb ÷ 4.11 lb/gallon = 5.84 Gallons

In short, a 30 lb propane tank holds 5.84 gallons of propane.

How Many Gallons Of Propane In A 100 Lb Tank? (Example 3)

Let’s say you have an empty 100 lb propane tank and want to fill it to the max. How many gallons of propane do you need to fill a 100 lb propane tank?

We have to use those two rules we have used in the introduction.

Applying the 80% capacity rule: A 100 lb propane tank actually holds 80 lb of propane when completely full.

Applying the LPG density: We have to divide these 80 lbs of propane by 4.11 lb/gallon to get to gallons like this:

100 lb Tank Capacity In Gallons = 80 lb ÷ 4.11 lb/gallon = 19.46 Gallons

In short, a 100 lb propane tank holds 19.46 gallons of propane.

These are just 3 examples. If you have a 10 lb tank or a 200 lb tank, you will need to check this next all-encompassing propane tank lb to gallons chart:

Propane Tank lb To Gallons Chart

With this chart, you can find how many gallons of propane go in pretty much any available propane tank. Hopefully, you can now calculate or read off the chart the amount of propane in gallons that goes into lb-sized propane tanks.