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Fuel Cost Calculator

Enter the distance, fuel economy and fuel price to see the fuel a trip needs and its cost in total, per person and per mile or km. Economy can be L/100 km, km/L, or US or UK mpg. Driving 300 km each way at 6 L/100 km, with fuel at 1.80 a litre, uses 36 litres and costs 64.80.

Runs entirely in your browser

Updated

How to use the Fuel Cost Calculator

  1. 1Enter the one-way distance in kilometres or miles, and tick Return journey if you are coming back.
  2. 2Enter your car's fuel economy and choose its unit.
  3. 3Enter the fuel price per litre or per gallon.
  4. 4Optionally enter how many people are sharing the cost.

How it works

Everything is converted to kilometres and litres first. Fuel needed = distance in km × litres per 100 km ÷ 100, and cost = litres × price per litre.

Miles per gallon is converted with exact definitions: a mile is 1.609344 km, a US gallon 3.785411784 litres and a UK (imperial) gallon 4.54609 litres. That is why 30 mpg in the US (7.84 L/100 km) uses more fuel than 30 mpg in the UK (9.42 L/100 km) — a UK gallon is about 20% bigger.

Official economy figures are measured in test conditions; motorway speed, traffic, load, cold weather and air conditioning usually raise real consumption. Use your car's trip computer or a recent fill-up for a more realistic figure.

The cost covers fuel only, not tolls, parking, wear or depreciation. Everything is calculated in your browser.

The formula

fuel (L) = distance (km) × economy (L/100 km) ÷ 100 cost = fuel × price per litre
mpg (US) → L/100 km: 235.215 ÷ mpg
mpg (UK) → L/100 km: 282.481 ÷ mpg
km/L → L/100 km: 100 ÷ km/L

Worked example

A 300 km drive each way, 6 L/100 km, fuel at 1.80 a litre, three people sharing

  1. Distance: 300 × 2 = 600 km
  2. Fuel: 600 × 6 ÷ 100 = 36 litres
  3. Cost: 36 × 1.80 = 64.80, or 21.60 each

Result: 64.80 for the trip, 21.60 per person.

Tips and common mistakes

  • Use a recent real-world figure rather than the brochure economy for long trips.
  • For a car share, agree whether to split fuel only or a per-mile rate that includes wear.
  • Check the fuel price where you will fill up; motorway stations are often dearer.
  • Compare with the EV Charging Cost Calculator if you are choosing between cars.

Frequently asked questions

How do I calculate fuel cost per mile?
Divide the price per gallon by the miles per gallon. At 3.50 a US gallon and 25 mpg, each mile costs 0.14.
Is UK mpg the same as US mpg?
No. The UK gallon is about 20% larger, so the same car shows a higher mpg figure in the UK. Choose the right one, or use L/100 km.
How do I find my car's real fuel economy?
Fill the tank, reset the trip meter, and at the next fill-up divide the distance driven by the fuel added. Many cars also show an average on the trip computer.
Does it include tolls or parking?
No. It covers fuel only; add other trip costs separately.
Can I use it for a motorbike or van?
Yes. It works for any vehicle; enter that vehicle's fuel economy.
Is anything sent to a server?
No. The calculation runs in your browser.
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