How Long Does 20lb Propane Tank Last?

Propane is a popular fuel choice for people who cook outdoors – be it a camping trip or just Sunday afternoon BBQ. If you are camping with the family or a large group and plan to carry a Propane tank, a large 20lb is ideal. But you must be wondering how long does 20lb propane tank lasts?

When used with a common 2-burner camping stove at 20,000 BTU output, the 20lb Propane tank will last 21 hours at full burner flame. This is the most common equipment used with a 20lb tank.

If you are using other equipment that has different BTU ratings, the run time will vary greatly. The below table summarises the run time of a full 20lb propane tank at most common BTU ratings.

Equipment Rating20lb Propane Tank – Run time
7,500 BTU57 hours
10,000 BTU43 hours
15,000 BTU29 hours
20,000 BTU21 hours
30,000 BTU14 hours
3,5000 BTU12 hours
40,000 BTU11 hours
50,000 BTU8.5 hours
60,000 BTU7 hours
80,000 BTU5.5 hours
Table of run hours of 20lb propane tank at different BTUs

I have created a simple googlesheet tool to calculate the run time of your Propane tank if you are planning to use it at different BTU ratings. Check out the calculator here.

How Long Does 20lb Propane Tank Last

How many BTUs are in 20lb Propane Tank?

BTUs are British Thermal Units – a measure of energy stored or consumed. 1lb of Propane contains 21,594 BTUs.

By that measure, a 20lb Propane tank has 431,880 BTUs.

If you want to calculate your equipment run time on a 20lb Propane tank, just divide 431,880 by the equipment BTU rating and you will get its run time in hours. For example, if you have a camping stove rated at 20,000 BTUs;

Run time (hours) = 431,880/20,000 = 21.59 hours

How to estimate remaining fuel in your 20lb tank?

This is one of the most important questions one faces while cooking outdoor. You have been using your tank for a while, and suddenly you realize, “am I running out of gas soon?” “Should I refill?”. How to measure the remaining fuel in your 20lb tank?

There are 3 ways to measure the level of fuel left in your tank.

1. Use hot water method

This is a simple trick that will give you the level of Propane left in your tank. From this level, you can roughly estimate the weight of Propane left and can calculate the run time from there. To do this, follow the following simple steps:

  1. Warm up some water in a cattle
  2. Slightly tilt your 20lb propane tank and pour the warm water over its surface from the top. Make sure the water stays in contact with the surface all the way to the bottom.
  3. Staighten up the tank and starting from the top, place your hand on the tank surface and slowly slide down, feeling the temperature of the metal.
  4. Mark the area where the metal goes from warm to cold. This is the current Propane level in the tank.
  5. From this level, you can roughly estimate the weight of Propane left. For example, If the mark is halfway down, the tank is half full and has roughly 10lb of Propane left.

2. Weigh the tank on a scale

Another method is to simply weigh the tank on a scale if you have easy access to a weighing machine or scale.

marking of tare weight of 20lb propane tank

If you closely look at your tank, there are a few markings on the tank. One of them will be the Tare Weight (marked TW). This is the weight of the empty tank without any propane. For a 20lb Propane tank, the tare weight is around 17 lb (see picture above)

Now, measure your tank and minus the tare weight from it, and you will get the weight of Propane left in the tank. For example, if the total weight of the cylinder is 27 lb and the tare weight is marked as 17 lb, then the amount of gas left in the tank is 27 – 17 = 10 lb.

To measure the weight, you can use one of those digital scales specially designed for propane tanks. I would recommend this one from Ozeri. It has a colored gauge with a digital display to immediately tell you how much the weight of the tank is. It is small so you can sneak one into your accessories bag.

If you want to go more digital, I also found a “smart scale” that you can place under your tank. It connects to your phone via Bluetooth and keeps you up to date about your tank usage. Here is the link to check on Amazon.

3. Install a pressure guage

This one is probably the easiest of all three. Instead of calculating the weight and run time of the tank, you will just install a cheap pressure gauge (like this one) and know instantly when your tank is going to run out of gas.

Where can I refill my 20lb large propane tank?

One of the most promising features of a 20lb large propane tank (or any large propane tank) is that it can be refilled over and over again. This saves you from buying a new cylinder every time you run out of gas. Compared to this, the portable propane tanks are not refillable (you can, but it’s against the DOT rule to transport them across state lines)

Once your tank is low on gas or completely empty, you can either refill them at your local station or exchange them for a filled tank. Exchanging them saves time. You just have to turn in your empty tank and pick up a filled one at the spot.

The following retailers have exchange/refill points all over the US and you can easily find one near you.

  1. Walmart: At most of walmart shops, you may exchange your empty tank for a full one. They welcome Blue Rhino, AmeriGas, Flame King, and Backyard Grill among others and will fill your tank at a lower price than before.
  2. Home Depot: Home Depot, like Walmart, accepts all types of empty propane tanks and replaces them with filled ones.
  3. Lakes Gas: If you live in the upper midwestern United States, you can trade in your empty propane cylinder at any nearby Lakes gas station and get a new one. You may locate your closest location by entering your zip code here.
  4. RapidXchange: You can exchange old propane cylinders at a RapidXchange station to get a full one.They serve the majority of the states, and you may find your nearest RapidXchange station on their website.
  5. Blue Rhino: You can return your empty propane tank to a Blue Rhino station and get a fresh one. You can substitute any other brand of propane for Blue Rhino without difficulty, as you would with other merchants. The only exception is that the tank must be in good working order. To locate the nearest Blue Rhino station, text FIND to 75653 or go to this page to look up near your zip code.
  6. AmeriGas: AmeriGas also offers a propane tank replacement service. They work with third-party merchants to increase their geographical footprint. You may drop off your empty tank at any of these stores and pick up a new cylinder. Please note that not all stations exchange old tanks (although the majority do). To find out where you can exchange your propane tank, go to this page and enter your zip code, then apply the filter on the right side labeled “Propane Tank Exchange.”

Conclusion

Large 20lb propane tanks are ideal for cooking outdoors during your camping trip. They can last for a couple of weeks if you are doing moderate cooking. Depending on your BTU consumption, you can easily estimate the continuous run time of your propane tank using this calculator.

Once empty, you can easily exchange or refill it at any gas station without many hurdles. They can be refilled over and over again and only need recertification every once in a decade.

FAQs

How long does 20lb propane tank last on a fire pit?

A typical propane-powered firepit has a 60,000 BTU rating. At full flame, a 20 lb propane tank should last for up to 7 hours.

How long will a propane heater run on a 20 lb tank?

A single burner Mr. Buddy propane heater is rated at 9000 BTU. If connected with a 20lb propane tank, it should last for up to 48 hours continuous use. You can follow my guide on how to connect portable propane equipment to large propane tanks.

Can propane tanks freeze up?

Propane is considered a good camping gas because it works at lower temperatures without freezing. It can work as low as -42 Degrees Fahrenheit.

Do propane tanks go bad?

Propane gas has no expiry and can be stored indefinitely without degrading. However, you will have to recertify the metal tank which is storing the gas. In the US, the recertification is done after every 12 years. In Canada, it is done after every 10 years.

Recommended Camping Gears: I have compiled a list of my favourite camping gear in one place. The selection is based on my own personal experience using them for many years camping as well as feedback from fellow campers. Check them out on my Recommended Camping Gears page