This article will provide you with all the information on how many BTUs are in a gallon of propane and also some useful tips on how to calculate them.

By

Rodney Nestor

Research Writer

Rodney holds a Master’s degree in Arts and apart from working as a freelance writer, is a rather successful author of science fiction stories published in several literary read more

Last updated: September 09, 2023

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When you purchase or fill up a propane tank, there are several different elements to consider. First, there is the weight and size of the tank, but you also need to understand the BTUs and measurements that coincide.

Having a better understanding of the details and configurations of your propane tank will better prepare you to use the tank and get the most out of it. Understanding how many BTUs are in a gallon of propane is one of those details you should know.

A BTU is a standard of measurement. These letters stand for British Thermal Unit, and ultimately, each BTU is one unit of energy or heat. The measurement reflects the energy required to heat or increase a temperature specific to an element.

In this guide, we will share with you more details about BTUs and how many are in your propane tank. We will break it down to several sizes of tanks and walk you through everything you should know about the topic.

How many BTUs your propane holds will ultimately depend on the size of the tank. Different sizes of tanks hold different levels and amounts of propane. With that in mind, different sizes of tanks will also host different BTUs.

You will need to understand the BTU output for operating things like generators, grills, appliances, and more. Generally speaking, you need a specific level of BTUs based on the square feet or the total space that you need to accommodate with the source. There are calculations you can do as well as handy calculators on the web.

Being familiar with the general BTU levels of a propane tank will certainly help you be prepared for your task!

Below, we will break down various sizes of propane tanks and how the BTUs relate to each size.

**1 lb. Propane Tank**

First up is the traditional 1-pound tank. This is a very small tank, so you would immediately expect it to have fewer BTUs. In most cases, the larger the tank, the more it will contain. These tanks weigh about 4 pounds on average, and they are designed for portability or portable-type usages like a portable generator or a portable camping stove and things along those lines.

This size of tank measures about 21,545 BTUs.

**20 lb. Propane Tank**

When you step up to the next size of the tank, you go from that small 1 lb. model straight up to a 20 lb. model. These are one of the most common sizes that you purchase from stores for things like home generators, various appliances, and powering your grill. They are also popular for RVs and camping life too.

A 20 lb. propane tank holds approximately 4.5 gallons of propane. The propane weighs about 17 pounds, and a tank that is full will weigh about 35 pounds usually. The measurement for this size of the tank is 430,000 BTUs.

**30 lb. Propane Tank**

The 30 lb. propane tank increases even more in size and capacity. This size of the tank is most commonly used for larger appliance operations, large or commercial grills, and even large generators. It’s a good in-between size if you use your propane tank quite a bit.

The numbers increase astronomically, as you can see with each upgrade in size. This tank contains approximately 649,980 BTUs.

**40 lb. Propane Tank**

If you operate a food truck or do a lot of commercial grilling, this might be the size of the propane tank that you’re using. You might also be using much larger tanks. It likely depends on what types of crowds you’re serving and what your truck can best host.

Of course, there are others uses for a tank this size, but this gives you a good indication. A 40 lb. propane tank holds slightly over 9 gallons of propane and weighs about 70 pounds. It measures approximately 860,540 BTUs.

**100 lb. Propane Tank**

A 100 lb. propane tank is large and in charge! At 100 pounds of propane, you’re looking at a tank that is near 4 feet tall and will hold close to 25 gallons of propane. They fill a gap between the small tanks and the really large tanks, particularly when space is a concern.

This tank hosts about 2,160,500 BTUs.

**5-Gallon Propane Tank**

A 5-gallon propane tank is very similar to a 20 lb. propane tank. These tanks are perfect for portability such as camping or grilling and can also operate small appliances. This is what you will find at traditional retail stores that sell propane tanks or refills a lot.

This size of the tank contains somewhere around 457,510 measurements for BTU.

**250-Gallon Propane Tank**

This size of the tank is reaching the exponential size and is more like the tanks that you will see grounded outside of homes and businesses. You probably won’t see them portable very often. The tank itself measures about 7 feet long and weighs more than 1,000 pounds when full.

These tanks hold a lot of propane. The BTU measurement is about 22,875,500.

**500-Gallon Propane Tank**

Finally, we reached one of the largest tank sizes on the market. The 500-gallon tank is a permanent fixture used for a home or business. These tanks typically measure somewhere around 10 feet long. When filled to the 80% rule, these tanks hold 400 gallons. You’re talking about more than 1,600 pounds of propane alone. And that isn’t counting the size and weight of the tank! When you count the tank, it’s close to 3,000 pounds.

In terms of BTUs, this monstrosity has approximately 45,751,000 in it.

On average, propane tanks hold about 92,000 BTUs for every gallon of propane. When you use a calculator, this is likely what the number will be based on. This isn’t an exact number, but, in most cases, you can take 92,000 times the number of gallons in the tank to figure the BTUs each tank holds.

It’s a standard number that you can use across the board. Keep in mind that this is not for the pounds of propane but the actual gallons of propane. So, a 20 lb. propane tank holds about 5 gallons of propane when full. Therefore, when completely full, a 5-gallon tank will have approximately 460,000 BTUs.

You can also use this same calculation with other sizes, and if you test it against the numbers above, you will see they all come very close. Be aware that the total size of the cylinder holding the propane could make a slight difference in the numbers.

What exactly does this mean, right? You have the BTUs, you know your gallons and your pounds, but how do you know the rate at which the propane will burn? The burn rate gets slightly more complicated because it depends on the consumption of the product that is burning propane.

So first, you need to know what the BTU of your appliance or usable item is. They always tout the BTU information if you’re cooking on a grill. Find this number to do the calculation. We also know that about 1 gallon or 4.24 pounds of propane uses about 92,000 BTUs, right?

So, to find your consumption rate, divide 92,000 by the number of BTUs from your appliance. Once you have that number, you can multiply it by the propane in your tank to get your burn rate.

To recap – first find your consumption rate. Multiply your consumption rate by the propane in your tank, and that is your burn rate.

To make the most out of your propane grill and your propane tank, you need to be sure you have all the right parts and connections. An overflow valve that is DOT approved, like the Flame King’s option, is ideal.

If you’re looking at propane grills and trying to determine how many BTUs you need or the right size of a propane tank, here is the general rule. For your grill to be effective, you want anywhere from 80-100 BTUs for every square inch of cooking surface on the grill.

This exception is for an infrared grill, which heats slightly better and only needs about 60-80 BTU each square inch.

If you keep these numbers in mind, you can look at grills, calculate how many BTUs they have per square inch of cooking surface, and see where it measures up. Does it fall within 80-100 per square inch? If not, it might not have enough heating power to do a really great job.

While a fire pit or fireplace is not the same as a propane grill, it’s a similar concept. You need to determine the space that the device needs to heat. Here, you have to consider factors like the weather, the environment, and even the placement of the fireplace or heater.

Things like the wind could affect your BTUs and the effectiveness of the appliance in question. To give you a range, your fire pit or fireplace could have BTUs anywhere from 40,000 to 150,000.

If you have a larger space or fight more wind, you will need to consider higher levels of BTU. Lower numbers will likely be sufficient if you’re just using a small fire pit to put out a bit of heat and make a cozy setting on the patio.

It’s easy to determine how many BTUs are in a gallon of propane when you understand how each gallon measures up. BTUs are a unit of measurement, but you also need to keep other factors like your consumption and burn rates in mind to get the most use out of your propane.

Take the time to learn the concept; this will help you whenever you’re shopping for propane or propane-powered items.

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