Propane smokers have become a popular method of smoking over the years. They are easy, simple, and cheap, and you don’t have to mess around with charcoal or buy an expensive pellet smoker.
I have owned many different gas smokers over the years, and there have actually been multiple occasions where I’ve run out of propane mid-smoking without having a replacement ready. It was equally frustrating every time. Knowing how long a propane tank will last in your smoker is no doubt a good idea and I learned that the hard way.
For finding out how long a propane tank lasts, I have done some research and some testing of my own, which I will share with you in this article. We will look at how much propane smokers use, how to calculate it for your own smoker, as well as how to check how much propane is left in the tank you’re using.
Here’s the quick answer on how long a propane tank lasts on the average smoker:
As a general rule, a 20 pounds propane tank will last around 20 hours on most normal, medium-sized smokers. On larger smokers it can sometimes use propane twice as fast, which means a 20 pound tank will be used in around 10 hours.
What Factors Determines How Long a Propane Tank Will Last?
There are a few main things that are relevant when it comes to the propane usage on a smoker; the temperature, the BTU usage of the smoker, and the amount of propane in the propane tank
BTU Usage of The Smoker
BTU is basically a unit of measurement of energy in things such as propane. A propane smoker uses a certain amount of energy or BTU’s per hour which is how it heats up and cooks the food.
Most smokers uses around 30,000 BTU per hour when the burners are set to maximum, but this will vary a lot from smoker to smoker. Usually the BTU level of your specific smoker can be found in the manual you got when you bought it, or sometimes on the manufacturers website.
BTU Capacity in The Propane Tank
1 pound of propane has 21,600 BTU in capacity, which means a 20 pound grill has a total of 432,000 BTU’s.
This means that if you run a smoker that can use 30,000 BTU per hour with the burners set to max, a 20 pound propane tank will be gone in around 10 hours.
The reason I’m not saying the exact number is because of how many factors are involved which can change the result quite a bit. In reality, it’s hard to find the exact amount of propane that in reality will be used.
Some of the factors are; the outside temperature, quality of smoker, smoker size, smoker model, type of meat you’re smoking, and so on.
Ironically, a rough estimation is the most precise way guessing how long a propane tank will last. And to be honest, it’s really all you need for in the real world when using a propane tank on a propane smoker.
Let’s quickly talk about the temperature. If you’re firing at a lower temperatures the burners are going to use less propane. If you want to increase the temperature, the burners have to use more propane.
As mentioned, there is really no way of giving a precise theoretical answer to the BTU’s are required for a certain temperature, as there are just too many factors involved. I think you’re better off by just knowing roughly what’s going on.
A general rule, if you smoke at 225-250 degrees Fahrenheit (which is quite common when smoking), you’re probably going to use a 20 pound propane tank in those 20 hours which means that the smoker must use around 20,000 BTU per hour at this temperature.
How to Calculate the Propane Usage on Your Smoker
We will now look at how to calculate the propane usage yourself for your smoker. Even though it’s hard to get the theoretical results to match with the real world results, it will still give you a general idea. For these reasons, it won’t really hurt skipping this part of the article. It’s more for those who want to calculate it themselves.
At full strength, the time a propane tank will last will be the BTU capacity in the propane tank divided by the maximum BTU per hour of the smoker.
Let’s say you have a 15 pound tank, and a smoker that uses BTU of 25,000 when the burners are set to max.
1 pound of propane has 21,600 BTU’s, which means 15 pounds of propane has 324,000 BTU’s.
The propane tank can then be found by dividing the tanks BTU capacity with the smokers BTU usage, in this case: 324,000 BTU divided by 25,000 per hour which is 13 hours.
This is if the burners are set to maximum which you’re obviously not going to do when smoking, so let’s look at the BTU usage at lower burner settings.
How to Find the Propane Usage at a Lower Burner Settings
Usually your smoker will tell you the temperature inside. By adjusting the burners you are, of course, going to alter the temperature. So, let’s look at how changing the burners will change the propane usage.
The K factor
To calculate how long a propane tank will last at lower burner settings, you first need to factor in something called the “k factor.”
The k factor is a certain number between zero and one, that a bunch of really smart people assigned to different cooking temperatures.
The chart on the right shows the different k factor values at low, medium and high settings, as well as how many burners are used.
How the K factor Fits In the Equation
By looking at the chart, you can find the specific k factor value that fits for the smoker you have.
For example, let’s say you’re using 4 out of 6 burners and that they are all set to medium. In this case, we can see on the chart that the k factor is 0.49.
All you need to do to use the k factor is to multiply it by the maximum BTU usage of the smoker.
Let’s say the maximum energy output level of your smoker is 25,000 BTU. If the k factor is 0.49 when at medium then the smoker must use 12,250 BTU’s per hour.
Also, let’s say we have a 20 pound propane tank, which has a capacity of 432,000 BTU’s.
Then, to find out how long the propane tank will last on this smoker, all we need to do is divide the 432,000 BTU with the 12,250 BTU’s per hour which is 35 hours.
This is how long the propane should theoretically last on this smoker, at this specific k factor. Again this result, might not be completely true in the real world, but it will definitely give as a good idea of how long the propane tank will last on our smoker.
How to Find Out How Much Propane is Left in The Tank
There are two pretty simple methods of estimating how much propane is left in the tank.
1. Using Water
This method is pretty cool, actually. Simply take some water and pour a bit on the side of the tank. If you run you hand down the side, you’ll notice a point where it goes from hot to cold, which is where the propane is. This is because the propane absorbs the heat from the water. I found this cool video which explains it better than I can.
2. Weighing The Propane Tank
This is quite straight forward, and probably the most precise method, if you have some way to weigh the tank.
Simply substract that weight of the tank if it were empty (which is also called the tare weight, or TW) with the weight you get from weighing it.
For example, if the propane tanks Tare Weight is 17 pounds and you weigh it to be 30 pounds there must be 13 pounds of propane left to use.
How Long Does a 15 pound Propane Tank Last on a Smoker?
A smoker uses around 20,000 BTU per hour when smoking at 250 degrees Fahrenheit. This means a 15 pound propane tank will last for around 15 hours.
How Long Does a Propane Tank Last at 250 Degrees?
At 250 degrees a 20 pound propane tank will last around 20 hours.
Is a Propane Smoker Even Worth It?
If you don’t already have a propane smoker, it might be worth it talking about whether or not you should even get one.
Propane smokers are definitely a very cost effective option, as opposed to many of the modern grills you can get today. On average, It’s also quite a bit cheaper to purchase a propane smoker than an electric, smoker although electric smokers are cheaper to run.
Propane smokers are also very easy to use and delivers a good final product. No, you may not get the same flavor as on a charcoal grill or a pellet grill, but the flavor is nevertheless good. The flavor is also better than on an electric smoker.
If you’re interest in a propane smoker check out my review on the Smoke Hollow 44241G2 propane smoker. I’ve owned this smoker for many years, and I think it’s a great option. Even if you don’t want that specific smoker, you will learn a lot about how propane smokers work simply by reading the review.
Thanks for reading!