How Much Fuel to Take

Running out of fuel on the last morning is a common and avoidable annoyance, and carrying three times what you need is a common and avoidable weight penalty.

Work From Boils, Not Days

Fuel use depends on how many times you boil water rather than how many nights you are out.

Count actual boils: coffee, breakfast, an evening meal, a hot drink. For most people that is two to four half-litre boils per person per day.

Then estimate fuel per boil and multiply. That gives a real figure rather than a guess.

The Rough Numbers

• A canister stove uses roughly ten grams of gas per half litre boiled
• Conditions change that substantially, in both directions
• A small canister holds around a hundred grams of fuel
• So roughly ten boils, in fair conditions
• Cold, wind and altitude all increase consumption sharply

Where a range pairs stoves with pot sets, of the kind catalogued at alocs-us.com, a lid and a well-matched pot size affect fuel use as much as the stove does.

What Increases Consumption

Wind, above everything. An unshielded stove in a breeze can use several times the fuel of a sheltered one.

Cold, which reduces canister pressure and means starting with colder water.

Snow melting, which is enormously fuel-hungry and should be calculated separately at several times normal consumption.

Altitude, and cooking rather than only boiling.

Use a Lid

The cheapest fuel saving available. A lid can cut boil time substantially, and boil time is fuel.

Most people boil with the lid off out of habit.

Weigh the Canister

The practical trick for part-used canisters, which are otherwise unknowable.

Note the empty weight, which is usually printed on it, and weigh the canister. The difference is the fuel remaining.

Doing this before a trip removes the guesswork entirely.

Carry a Margin

Twenty per cent over the calculation, and more in cold weather or where resupply is uncertain.

Two Small Beats One Large

A part-used canister is dead weight you cannot assess in the field, and a spare small one is insurance.

Fuel Cannot Fly

Plan to buy at the destination and check availability first.

Shelter the Stove

Which does more than any efficiency claim.

Keep a Record

Noting what you actually used on a trip, against the conditions, turns the next calculation from an estimate into a measurement.