Fuel Canister Calculator
How much gas is left in a part-used backpacking stove canister, and how much fuel and how many canisters to bring for a trip.
Result
Enter canister weight now and empty canister weight to see the result.
https://calcgallery.com/hobbies/fuel-canister-calculator/
Results are arithmetic on the figures you enter and are estimates. Products, materials and animals vary, so follow the maker's instructions and label, make a test piece where it matters, and ask a vet about feeding. Nothing here is safety or veterinary advice. Read the full disclaimer
How to use the Fuel Canister Calculator
- Choose whether you want to know what is left in a canister or how much to bring.
- Enter the net weight of fuel printed on a full canister.
- To see what is left, weigh the canister without its cap and enter that and the empty weight.
- To plan a trip, enter people, days, the water each person boils a day and the fuel your stove uses to boil a litre.
- Add spare fuel for wind and cold if you want a margin.
How it is calculated
How much is left fuel left = weight now − empty weight share left = fuel left ÷ net fuel on the label water left = fuel left ÷ fuel to boil one litre days left = water left ÷ water boiled a dayHow much to bring water = people × days × water per person per day fuel = water × fuel to boil one litre × (1 + spare) canisters = ⌈fuel ÷ net fuel in one canister⌉Every figure is one you enter: the page has no table of brand weights, because empty canisters of the same nominal size differ from maker to maker. The label’s net weight, a kitchen scale and your stove’s measured burn are enough.
Measuring your stove’s burn
Fill a pot with a litre of cold water, weigh the canister with the stove removed, bring the water to a rolling boil, and weigh the canister again. The difference is your fuel per litre. Do it with the pot and lid you will carry; a lid can cut the fuel noticeably. If you use a windscreen, measure with it too, and follow your stove maker’s instructions on windscreens.
With your numbers
- Water = 2 × 4 days × 1 qt = 7.6 L
- Fuel = water × 10 g a litre × (1 + 10%) = 2.9 oz
- Canisters = ⌈fuel ÷ 8 oz⌉ = 1
Quick reference
Your stove’s real burn varies with wind, cold, altitude and pot size. Measure it on a trial boil where you can.
| Example | Result |
|---|---|
| 8 oz canister now weighing 10.5 oz, empty 7 oz | Fuel left: 3.5 oz |
| 4 oz canister now 5 oz, empty 3.6 oz | Fuel left: 1.4 oz |
| 2 people, 4 days, 10 g a litre | Canisters to bring: 1 |
| Solo, 5 days, 2 qt a day, 12 g a litre, 20% spare | Canisters to bring: 1 |
| 230 g canister now 250 g, empty 147 g | Fuel left: 103 g |
| 4 people, 5 days, 1.5 L, 12 g a litre, 25% spare | Canisters to bring: 2 |
| 2 people, 3 days, 1 L, 10 g a litre, 110 g canisters | Canisters to bring: 1 |
Common questions about the Fuel Canister Calculator
- How do I know how much gas is left in my canister?
- Weigh it. The fuel left is the weight now minus the weight of the empty canister. The empty weight is the gross weight minus the net weight if the label gives both, or you can weigh a used-up canister of the same size. The share left is that fuel over the net weight on the label.
- How much fuel do I need per day backpacking?
- It comes down to how much water you boil and how much fuel your stove uses per litre, and wind, cold, altitude and pot size all change the second. Take the figure from your stove maker, or better, boil a measured litre at home, weigh the canister before and after, and use that.
- Why does the float test or shaking the canister disagree with this?
- Floating a canister in water or judging by the slosh are rough guides. A kitchen scale reading to a gram is more reliable, and it is the method this page is built on.
- Does cold weather change how much fuel is left?
- No, the fuel left is the fuel left. Cold does make a canister deliver gas more slowly and a stove burn less efficiently, so it may use more fuel per litre, which is why the page offers spare fuel for the plan.
- Can I use this for a liquid-fuel stove?
- The planning mode works for any stove if you know its fuel use per litre in grams. The canister size is a weight of fuel, and fuel bottles are sold by volume, so enter the weight of fuel a full bottle holds: weigh it full and empty and take the difference. The left mode assumes a sealed canister you can weigh.