How much fuel do you need for a backpacking trip?
Packing for a backpacking trip takes a little more finesse than packing for a canoe trip. You feel every extra gram. This requires difficult decisions on gear: to take, or not to take? Is it essential? Is it not essential but worth the weight?
Fuel, for most of us, is in the essential category. Being relatively heavy however it is desirable to bring only what you'll need. How do you calculate how much fuel you will require?
There are a number of factors that affect fuel use. We'll talk about some of the more important ones to consider and how to calculate what you'll need. For those who want a fast answer jump to the bottom of this post for some rough guidelines, and check out our quick tips.
Factors that influence how much fuel you will burn
- What kind of cooking/heating you will be doing. Are you simply boiling water, or simmering rice?
- Temperature of the water. Add a couple minutes of burn time for heating very cold water, and especially if melting snow.
- Altitude. This won't affect your water boil times a whole lot but will greatly affect cooking times. Because water boils at a lower temperature at high altitude it takes much longer for food to cook.
- Use of reflectors and windscreens. These decrease burn times, sometimes quite significantly.
What you need to know to calculate how much fuel you will need
You need to know how many people are coming on the trip and how long the trip is so you can get an idea of how many litres of water you will be boiling. This would include meals and hot drinks. A general rule of thumb is 1L of water per person per meal. If actually cooking you can use the same formula as the stove burn time would be roughly the same.
You also need to know something about your stove - this may be boil time (how long it takes to boil a litre of water) and/or burn time (how many minutes it takes to burn a set amount of fuel). You can look these up under your stove specs (on your packaging or the manufacturer's website).
If you don't mind doing some homework you can get a fairly precise estimate on the fuel you will need by calculating water needed for each meal rather than the basic 1L/person rule. These calculations work for both canister and liquid fuel.
For example a 3 day trip for 2 people using an MSR WindPro II canister stove could be calculated like this:
- How many litres of water will need to be boiled in total? Assuming 2 hot meals and drinks a day: 2 people x 2L = 4L per day, 3 days x 4L = 12L total
- How much fuel will be needed? There are a few ways to calculate this. According to MSR's specs* on this stove it will boil 1.8L of water per oz of fuel. 12L divided by 1.8L = 6.67, so you would need 6.67oz of fuel. MSR also claims the boil time of this stove is 3.6 minutes for 1L. You could calculate how long you'll need to run your stove: 3.6 minutes x 12L = 43.2 minutes. Manufacturers will often list how long a certain sized canister will burn so it can be useful to know burn minutes required.
Therefore an 8oz (227g) canister would be more than enough for 2 people going on a 3 day trip based on the above criteria, but a 4oz (110g) canister wouldn't be enough. We figure it's best to err on the side of too much.
*Note: you will find discrepancies with many published specs. We know we have! If things don't compute quite right go with the most conservative guess so you don't end up eating a cold meal or missing your cup of coffee.
We based the following guidelines on MSR's liquid fuel bottles and canister sizes. The time spans are a rough estimate based on 1L/person/meal for 2 hot meals a day in ideal conditions.
- cover your pot to keep the heat in
- use reflector bottom and windscreen (remote fuel bottle/canister only!)
- burn a quarter turn below max power so you don't get heat loss around your pot
- be fully prepped before you light your stove so you don't waste burn time
And one more tip for canister users
How do you tell how much fuel is left in a canister? Fill a pot with water and float the canister in it right side up (tilt the canister to release any air bubbles underneath). The more fuel there is in the canister the deeper in the water it will sit. MSR IsoPro canisters have a basic float diagram on the side for reference.