Checked 15 October 2026. What was checked. How these pages are maintained.
Trip fuel formula
Metric: litres used = distance × (L/100 km) ÷ 100. Cost = litres × price per litre. US: gallons used = miles ÷ MPG. Cost = gallons × price per gallon. Real trips vary with speed, heat, cargo, and winter fuel.
Worked example
A 400 km trip at 8.0 L/100 km uses 32 litres. At $1.55/L that is $49.60. The same trip at 28 MPG over 250 miles uses about 8.93 gallons; at $3.80/gal that is about $34.
Highway ratings assume steady speed. Winter fuel, a roof box, and city traffic can add 10–20%. Carry a reserve on long gaps between stations in the North or on the Prairies.
Litres per 100 kilometres, then the pump
A 650 km drive at 7.2 L/100 km uses 650 × 7.2 ÷ 100 = 46.8 litres. At $1.62 a litre the trip is 46.8 × 1.62 = $75.82. The page also shows the cost of 100 km, which at that efficiency is 7.2 × 1.62 = $11.66. That second number is useful when you are comparing two cars and you do not care about a particular trip.
Switch to miles and MPG and the formula flips. Gallons = miles ÷ MPG, and you type a price per gallon. Do not leave a litre price in the box after you switch units. A 400 km trip and a 250 mile trip are not the same road. Convert the distance first, or stay in one system for the whole line.
The rating on the window sticker
Natural Resources Canada publishes city, highway, and combined figures. A highway number assumes a steady speed with little cargo. Winter fuel, a roof box, a headwind, and short cold trips can add 10 to 20 percent. On a 650 km gap between stations, a 15 percent reserve on 46.8 litres is about 7 extra litres. This page will not add the reserve unless you raise the distance or the L/100 km yourself. It also will not split a trip across two different pump prices. Average them, or run the legs separately and add the dollars.
Common questions
Where do I find L/100 km?
On the window sticker, your trip computer, or the Natural Resources Canada fuel rating for the model.
Should I add a buffer?
Yes. 10–15% extra is reasonable for hills, traffic, and a reserve.