Knowing How Much Fuel to Pack

Packing fuel for something like car camping isn’t overly complicated and worrisome since you’re able to bring more than enough. Determining fuel needed for backcountry cooking, on the other hand, is a different game. Although it takes a bit more brain power and planning, it is possible to determine the amount of fuel you’ll actually need for a trip. This helps avoid wasted weight and space in your pack (and makes use of those partially full canisters!)

Make a meal plan and note which meals require stove top cooking time, or boiled water (and note how much water)

(Stove top cooking time for items being cooked in a pan over heat)
(Boiled water for instant, dehydrated or freeze dried meals, and hot beverages)

Find the following for your particular stove:

Your stove's manufacturing performance specs should note your particular stove's boil and burn times.

If not, you can do at home tests!

Finding boil time is simple and straight forward. Set up your stove and fill your pot with 1 L of water. Turn your stove onto high heat. Time how long it takes for the water to come to a boil. (ex. 1L = 3m 40 secs)

Burn time is also quite simple, but you'll need a weight scale:

Weigh your fuel canister and note how many grams it is currently sitting at. Note that this weight will include the weight of the fuel and the canister.
Turn the stove onto high heat and let run for 5 minutes. (Note on why to use high heat below)
Now re-weigh the canister.

The difference in weight determines how many grams of fuel the stove used in 5 minutes.
(ex. 5 mins = 11g of fuel)

With this, you can calculate how long a full canister would take to burn from full to empty with your stove (ex. 110g = 50 minutes)

Notes:

I use high heat because this will provide results using the highest level of fuel burning. If you were to test on low heat/low fuel expenditure, less fuel would be used in the testing time frame. Unless you constantly use low heat when using your stove, this will make your results inaccurate for cooking style (meaning you will likely underestimate how much fuel you need!)
It’s smart to do the tests at the same time if you have the means to! (Kills 2 birds with 1 stone)

If you don't have a weight scale and can't determine your stove's burn time, it's still possible to estimate the amount of fuel you'll need (it's just less accurate; see more below)

Using your stove's boil time, determine how many minutes of fuel use you will need to prepare all of your meals.

*If you need to do any stove top cooking, make sure to add the estimated total cooking time (including to heat up the pot or pan) to your total fuel use minutes (as displayed above)

Determine how much fuel you'll need using one of these methods:

Method A: General Guideline (Can use if you do not have your stove's burn time)

The following chart notes the average times typical canisters take to burn from full to empty in ideal conditions. (Ideal conditions meaning fair weather, air and water temperature, altitude, etc.)

With the example meal plan above, only 17.2 minutes of burn time is needed, thus a 110g fuel canister should be more than enough.

Method B: Calculated Gram Use Estimate (Weight Scale or Burn Time Required)

1. Using the fuel use minutes required for your trip, calculate what % this is of your stove's burn time.

ex: 17.2 / 50 = 34%

2. Convert the percentage of burn time into the amount of grams this represents for your fuel canister

ex: 0.34 x 110 = 38

Tips to help save your fuel:

Use a wind screen
Cook in a less exposed area (but NOT IN YOUR TENT)
Use a lid to contain heat
When boiling water, avoid lifting the lid to check if it’s boiling; When you see steam, you know it’s ready!
Be mindful of heat temperature. High heat – or even heating water to a full boil – isn’t always necessary
Always monitor your stove and turn it off as soon as possible
Have everything prepped and ready before turning the stove on (to avoid delays and wasted fuel time)
Plan meals that requires less cooking time (ex. boil water only)
If it’s cold out, lightly warm your fuel before use. This can be done with your body heat by stuffing the canister in your jacket.

How to measure remaining fuel in a partially used canister:

Some fuel canisters are refillable, while others have gauges or marking points to determine fuel levels, so it’s easy to know how much fuel you have left. Many isopropyl canisters aren’t like this, so you’ll need to figure out how much fuel is left on your own. You can simply do this with a weight scale.

But it’s not quite as simple as throwing the canister on the scale and calling it a day. That weight includes the fuel AND the canister it’s being held in. You’ll want to know how much the canister weighs so you can accurately measure the weight of a partially full canister.

The best thing you can do is to check the weight with a brand new canister. If the fuel weight is 110g, but is weighing in on your scale as 116g, you know the canister’s weight is 6g. Write this on the bottom of your canister with a permanent marker so you have a quick and easy reference the next time you weigh the canister.

Now knowing the weight of the canister, you can now simply throw the canister on the scale – subtract the canister weight – and voilà! You know how many grams are left in that canister.

Happy cooking!

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