Fuel Cost Calculator

Fuel Cost Calculator estimates how much fuel a journey uses and what it costs, from the distance, your vehicle’s fuel efficiency and the fuel price. It accepts kilometres or miles, km/L, L/100 km, US mpg or Imperial mpg, and prices per litre or per gallon, and shows every conversion it makes.

Fuel-efficiency figures come in several incompatible units, and mixing up US and Imperial gallons alone changes the answer by about 20%. A calculator that converts each unit with exact factors and shows its working lets you budget a trip or compare vehicles with confidence.

1. Enter the one-way distance and choose kilometres or miles.
2. Enter your fuel efficiency and choose its unit.
3. Enter the fuel price and whether it is per litre, US gallon or Imperial gallon.
4. Tick Round trip if you are coming back the same way.
5. Press Calculate fuel cost, then check the conversions and copy or download the summary.

• km/L, L/100 km, US mpg and Imperial mpg efficiency units
• Distance in kilometres or miles; price per litre, US gallon or Imperial gallon
• Converted distance, fuel used and fuel cost, with an optional round-trip total
• Exact conversion factors and every formula shown
• Plausibility checks for zero, negative, blank and extreme values
• No live prices or exchange rates fetched — the symbol is display-only

• Use your real-world average consumption rather than the official test figure.
• Check whether an mpg figure is US or Imperial before entering it.
• Add a margin for traffic, hills, heavy loads or air conditioning.
• Update the fuel price before each long trip.