Canister Fuel-Remaining Calculator

Every stove drawer and glovebox in the country holds the same mystery: a part-used fuel canister that sloshes when you shake it and commits to nothing. Shaking tells you fuel exists. It cannot tell you whether the can holds three boils or thirty — and that difference is a trip plan. This calculator removes the guessing. Weigh the canister on a kitchen scale, pick its size, enter the weight, and it gives you the fuel left in grams, the liters of water that boils, and the days it covers. The method is the one from our full answer to how much fuel is left in my canister?: gross weight, minus the empty can’s weight, is fuel. Nothing else about a canister is honest.

Weigh your canister

The empty-can weights behind the subtraction are the class figures used across this site’s fuel pages: about 95 g for the small can, about 128 g for the medium, about 195 g for the large. The steel cans are standardised across the major brands, which is why one table serves all of them — but if your canister’s base is stamped with its own empty weight, trust the stamp over our class figure, and the difference will rarely be more than a few grams either way. The burn rates are from our camp stoves compared dataset: about 14 grams per liter for a typical upright stove (the MSR PocketRocket 2’s published rating works out to 14.2), and about 10 grams per liter for an integrated system of the Jetboil Flash class, whose heat-exchanger cup keeps heat the open burners throw away.

A worked example

A medium canister comes home from a trip and weighs 260 g on the kitchen scale. Subtract the medium can’s roughly 128 g of steel and the fuel left is about 132 g — a little over half the can. On an upright stove in calm weather that is about 9 liters of boils, or four to five solo days of freeze-dried cooking at the roughly 2 liters a day our fuel-per-day answer budgets. The shake test would have called that can “some left.” The scale calls it a long weekend, exactly.

How to use it

1. Weigh the whole canister as it stands, cap on, on a kitchen scale that reads in grams. Guessing from a bathroom scale’s pounds is not accurate enough — the whole question lives in a 100-gram window.
2. Pick the size by the fuel figure printed on the label — 100, 230, or 450 g — not by how tall the can looks. If your can is an in-between size, pick the nearest and read the grams-left figure as approximate.
3. Run it twice if the weather is uncertain: once calm, once on the wind-and-cold setting. Pack for the second number. Cold canisters lose pressure and every boil stretches, which is the physics in why does my canister stove die in cold weather?
4. Write the grams left on the cap, with the date. Next season’s packing-you gets a number instead of another mystery can, and a shelf of weighed, labelled part-used cans is a fuel store, not a junk drawer.

As an Amazon Associate, Shelter Tactics earns from qualifying purchases. It never changes a score or a number on this page.

Questions people ask

Can I just shake the canister instead? You can learn that fuel exists, and nothing more. A can three-quarters empty and one a quarter empty both slosh audibly, and neither sound converts to boils. The scale is the only household instrument that answers the actual question, which is why this calculator is built on it.

My scale only reads in ounces. Can I still use it? Yes — multiply the ounces by 28.35 to get grams. The worked example above, a medium can at 260 g, reads about 9.2 oz. Weigh in ounces if you must, but convert carefully: a one-ounce error is 28 grams, which is two boils of error.

Does a cold canister weigh less? No. Cold changes the fuel’s pressure, not its mass — a can that flames weakly on a frosty morning may hold plenty of fuel that burns fine once warmed. Weigh first, warm second, condemn last.

How accurate is the days figure? It assumes a solo hiker boiling about 2 liters a day for freeze-dried meals and hot drinks, from our fuel-per-day tables. Real cooking with simmering burns a quarter to a third more; groups scale differently. Treat the days as a planning figure with the same honesty as the grams: close enough to pack by, not a promise.

Planning the trip this canister has to survive? How much stove fuel do I need per day? works the budget from the other direction — in calculator form at the Fuel-Per-Day Calculator, which also runs the white-gas math — and the whole set of stove and fuel questions lives at What People Are Asking About Stoves and Fuel.

Talk it over with other readers. The Shelter Tactics Community on Facebook is where readers compare notes on knives, lights, packs, and the rest of the kit — and where your questions help decide what we research next. Join the group →