How to Measure How Much Fuel is Left in a Backpacking Canister

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I love hot food after a cold day of hiking. It warms my spirits in the midst of nature. I feel alive. It’s also a lot healthier than cold food. If you want to boost a camper’s morale, then hot food is the way to go. I haven’t met someone who didn’t become a happy camper after eating some hot food. If you want to eat well on your next backpacking trip, then this article, How to Measure How Much Fuel is Left in a Backpacking Canister, is sure to help.

Let’s get started.

First Things First, Understand Your Gas Canister

If you know how to use your specific gas canister, then props to you. This short section will be a refresher. If you are a beginner, then you are going to need to learn from a mentor. That’s the way I learned and I recommend you do the same to understand what follows.

A tool is only as good as its user. Know how to maintain, start, shut off clean, and take care of your specific gas canister. Use a wind barrier, insulate it when in use, keep your canister warm, and monitor its fuel levels (as we’ll discuss how to later in this post). The more you know about it, the more you can effectively use it as it was meant to be used. When a gas canister becomes as familiar as the back of your hand, then monitoring fuel levels becomes a piece of cake.

When you get the weights for your gas canisters using one of these methods, be sure to understand your stove’s and canister’s burn time/weight ratio. Each brand is unique. Learn your canister. When you create your next backpacking trip’s meal plan, you will need to take the burn time/weight ratio into account to fully manage your trip.

Image Credit: Eelke

Method #1: Just Weigh Two Canisters

Of all the methods I am going to talk about here, this one is the most reliable. You will get a hard number to go off of.

For this you are going to need a calculator, digital scale, and two gas canisters of the same brand, one empty and another half empty or so. (For all these methods, the canisters need to be the same brand to best calculate the difference between the two.) You won’t get accurate results any other way. The digital scale is a specialty item, so it might be a bit pricey to get but it will do the job well.

Check out the following steps:

  1. Put the empty canister onto the digital scale and record its weight.
  2. Take the empty canister off the scale.
  3. Put on the other canister and record its weight.
  4. Calculate the difference between the two canisters.
  5. Congratulations! You now understand the weight difference between an empty and a nonempty gas canister.

The biggest drawback is you cannot do it in the field. Backpackers just do not bring a digital scale into the back country with them. It is superfluous. In other words, a digital scale will unnecessarily weigh you down.

Image Credit: patchattack

Method #2: the Back Country Water Buoyancy Test

Have you ever heard of the world-famous bath tub story of Archimedes the mathematician? Hiero, Archimedes’ king, suspected his goldsmith to be shortchanging his crown by not using 100% gold and creating a cheaper alloy with silver instead. He just did not know how to prove it.

Archimedes, not to be easily dismayed, took up the king’s challenge. He worked and worked trying to come up with a solution to the problem. He almost reached his breaking point and fretted throughout the night. After taking a trip to the city’s baths, he noticed the water level rise when he let his body sink into the pool. The displaced water could be measured and record the volume of his body.

By this line of reasoning he realized, since gold is denser than silver, a 100% gold crown should displace more water than a gold-silver alloy of the same weight. He solved the king’s riddle.

Archimedes then leapt naked out of the tub and rushed home shouting, “Eureka! Eureka!” Or, translated, “I’ve found it! I’ve found it!”

While I don’t recommend you run home naked after figuring anything out, Archimedes’ mythical story summarizes the method I am about to discuss in a short, humorous anecdote. This method is my go to in the back country. Unlike a lot of things in fresh water, gas canisters float thanks to the gas inside.


For this to work, you are going to need enough water to float a canister, a big enough pot to hold one, a black sharpie, and two gas canisters of the same brand, one empty and another half empty or so. Check out the following steps and you’ll know your fuel levels in no time flat:

  1. Fill your pot up to a sufficient level with water.
  2. Place the empty canister into the water and let it float.
  3. Gently tilt it to free up any bubbles that might be under the concave bottom of the canister.
    (This step increases accuracy).
  4. Sharpie the water line on it ‘with your eyeball.’ It helps to look at a feature or some words on the canister to help ‘eyeball’ your sharpie line. You don’t need to be perfect, but exactness does help.
  5. Repeat the appropriate steps for the second canister.
  6. Compare the two lines to get an understanding of how much fuel you have left.

When doing this, do not let any water inside the valve or into the canister; this will ruin your gas. You bought that canister with your hard-earned cash. You definitely do not want to destroy it.

Some brands like MSR and Jetboil have fuel gauges on their canisters to take care of the guess work for you. You should otherwise be all set to go.

Method #3: the ‘Shake and Gut Feel’ Test

If you do not have access to water or a digital scale or just want a quick and dirty method, then the ‘Shake and Gut Feel’ test is for you. I use this method regularly on my backpacking adventures whenever I am about to cook up a meal. It is amazing how good you can get at this method with a bit of practice.

You will need two gas canisters of the same brand, one empty and another half empty or so for this method to work. It’s quite simple really. Just check out the following steps:

  1. Put the empty canister in one hand and gently shake it to gauge its heft.
  2. Put it down and pick up the other one. Gently shake it to gauge its heft.
  3. Pick up both canisters and gently shake them to gauge their weight against each other.

For this method to work, there are a few caveats.

One, you need some knowledge. In other words, be able to answer these questions. What does the canister’s manufacturer say about how long the canister is supposed to last? How much have you recently used your canister? How many minutes does a full canister of your brand last?

Two, this method is not for beginners. Seasoned experts know their canisters, stoves, and journey inside and out. They can tell you how the weather will impact their cook time before you’ve even set up your tent. They know how to boil pasta on 5 minutes of fuel. Well, maybe not the last one. But you get the point, experts understand their stove; beginners do not.

Third, this method is a best guess, not an exact measurement. You will not get anything perfect out of this method, only a general idea of your fuel levels.

Do You Need Some More Adventure in Your Life?

Well, you should be all set to go. You have three solid methods at your disposal for your next backpacking trip. I am sure you will eat hot and healthy on your next adventure. When you know your fuel, then you can plan well.

If you enjoyed this article as much as I did writing it and want to check out another one, then I suggest you take a look at a previous blog post, Why Should You Even Consider REI Outdoor Travel Adventures? You need more fun in your life and REI is a great way to do it. They are my favorite outdoor brand by a wide margin. You are going to feel good after reading the blog post.

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If you have any thoughts, questions, or think I missed anything, do not hesitate to comment below and please share the article. Thank you so much and I hope you make it a great day!

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