What this calculator does#
It works out how many kilojoules your trip menu asks for, divides by the efficiency your stove and conditions realistically deliver, and converts that into grams of fuel and a canister or bottle to buy.
How the maths works#
Energy into the water. Heating a litre from your source temperature to boiling takes 4.186 kilojoules per kilogram per kelvin. From 10 degrees C that is 377 kJ per litre. If you are melting snow, we use 763 kJ per litre instead: 10 kJ to warm the snow from minus 5 to freezing, 334 kJ for the phase change, and 419 kJ to take the meltwater to boiling.
Delivered efficiency. This is the number that actually decides your fuel weight, and it is where most planning goes wrong. Base figures used: upright canister stove with a plain pot 34 percent, the same with a windscreen 45 percent, integrated heat exchanger system 62 percent, remote canister 40 percent, liquid fuel 38 percent, alcohol 25 percent. Wind then multiplies that: sheltered 1.05, light breeze 0.90, exposed 0.70, with a smaller penalty for heat exchanger systems because the fin ring shields the flame. Below 5 degrees C we apply a further 1.2 percent penalty per degree, to a floor.
Simmering is charged separately at about 1.8 g per minute for gas, 2.0 for liquid fuel and 2.6 for alcohol.
Margin. We add 15 percent, and note that the last 10 to 15 g in any canister is effectively unusable in cold weather.
Calibrating it against yourself#
The model is generic. You are not. Three trips of weighing will beat any calculator:
- Weigh the canister before the trip on a kitchen scale, to the gram, and note it.
- Cook as you normally do, and count the litres you actually boil.
- Weigh the canister on your return.
Grams used divided by litres boiled is your personal figure for that stove, pot and cooking style. Most people find it is 10 to 30 percent above or below the model, consistently, and after that you can plan fuel by multiplication.
Frequently asked questions#
How long does a 230 g canister last?#
For two people boiling 1.2 litres each per day on an upright stove in light wind, roughly three to four days. In cold and wind, closer to two. The variance is efficiency, not the canister, which is why the same canister gets wildly different reviews.
Does a windscreen work with an upright canister stove?#
A full windscreen around an upright stove can trap heat around the canister, which is dangerous. Use a partial screen that shields the burner without enclosing the canister, or use a remote canister stove, which is designed for a full screen.
How much fuel to melt snow?#
Roughly double what the same volume of stream water costs, because 334 kJ per kilogram goes into the phase change before the temperature moves at all. Always start with a little liquid water in the pot to avoid scorching the base and to speed the transfer.
Why does my stove get worse as the canister empties?#
Two reasons. The canister cools as fuel evaporates, dropping the pressure, and the blend fractionates because propane leaves preferentially, so the remaining fuel is more butane rich and holds less pressure. Both are covered in canister stoves in the cold.
Is alcohol lighter than gas for a long trip?#
Rarely. Alcohol carries about 26.8 MJ per kg against 45.8 for gas, and burns at lower efficiency, so the fuel weight roughly triples. The stove itself is far lighter, so alcohol wins on very short trips and loses badly on long ones.
Should I plan fuel per person or per litre?#
Per litre boiled. People plan by headcount and get it wrong, because a group of four sharing one pot boils far less than four people cooking separately. Count the litres your menu needs, then apply the efficiency.
Standards, sources and further reading
- Specific heat capacity of water, 4.186 kJ per kg per K, and latent heat of fusion of ice, 334 kJ per kg, standard physical constants.
- Lower heating values used: canister gas 45.8 MJ per kg, white gas 43.5, denatured alcohol 26.8.
- Delivered efficiency ranges are our modelled figures, described below, not laboratory measurements of specific stoves.
How this page is made. Every number here is either a published standard, a physical constant, or arithmetic we show in full so you can check it. Read our evaluation method and editorial standards, or tell us we got something wrong.
Last reviewed and updated 9 September 2026.