Fuel Cost Calculator
Work out what a trip costs in fuel, one way or there and back.
Total cost
£17.69
One way · 100 mi
Fuel
10.11 litres
Cost
£0.177 per mile
Please note: The result is an estimate and has been rounded. Actual costs and values may differ, and no rights can be derived from this calculation.
How this number is calculated
The blocks use your input. Change a value above and they update with it.
Step 1 · Total distance
Step 2 · Fuel
Step 3 · Cost
How the calculation works
The calculator combines the distance, your car's fuel economy and the price of fuel. Choose round trip and the distance is doubled.
The result is an estimate based on average fuel economy. A real trip can cost more or less depending on speed, load and weather. Miles, mpg and prices per gallon are converted to kilometres, litres per 100 km and price per litre before the calculation.
Formula
Cost = distance × trip (1 or 2) × fuel economy (L/100 km) ÷ 100 × price per litre
Assumptions
- Fuel economy is an average over the whole trip.
- The fuel price stays the same during the trip.
- Only fuel counts: no tolls, parking, maintenance or depreciation.
- For a round trip, the way back is as long as the way there.
Example calculations
The button fills in the calculator above, so you can carry on from there.
-
Commute, round trip
Total cost
£6.09
Distance 25 km · Fuel economy 5.8 L/100 km · Fuel price £2.10 per L · Round trip
-
Holiday drive, one way
Total cost
£156.00
Distance 1,200 km · Fuel economy 6.5 L/100 km · Fuel price £2.00 per L · One way
-
100-mile drive
Total cost
£25.75
Distance 100 mi · Fuel economy 8 L/100 km · Fuel price £2.00 per L · One way
Frequently asked questions
How do I find my car's fuel economy?
Check the trip computer. Or fill the tank, note the mileage, and at the next fill-up divide the litres you put in by the kilometres you drove and multiply by 100 for L/100 km, or divide the miles you drove by the gallons you put in for mpg.
Should I choose US or UK mpg?
Use the gallon of the country your figure comes from. A UK (imperial) gallon is 4.546 litres and a US gallon is 3.785 litres, so the same car shows a higher mpg figure in UK gallons. Other units can be converted with the Fuel Economy Converter.
How much does it cost to drive 100 miles?
That depends on your fuel economy and the fuel price. At 30 mpg (US) and 3.50 per US gallon, for example, 100 miles takes 3.33 gallons and costs about 11.67. The calculator also shows the cost per mile or per kilometre.
Why does my real fuel economy differ?
Speed, load, tyre pressure, air conditioning and weather all affect fuel use. Use an average over several fill-ups for a better estimate.
How do I split fuel costs with passengers?
Divide the total cost by the number of people sharing it. If a round trip costs 30 in fuel and three people share, each pays 10.
Does it work for diesel and LPG?
Yes, the calculation is the same for any fuel. Enter the fuel economy and the price of your fuel. A car on LPG usually uses more litres per 100 km than on petrol, so use its LPG figure.
Sources and checks
Sources
- Weekly road fuel prices | GOV.UK (opens in a new tab)
- Advisory fuel rates | GOV.UK (opens in a new tab)
- NIST Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically (opens in a new tab)
- NIST Handbook 44 (2026), Appendix C: General Tables of Units of Measurement (opens in a new tab)
How we check it
This calculator has 13 fixed checks: 11 calculations with a result that is fixed in advance, and 2 cases of invalid input that must be rejected. They all run automatically every time we publish; if one fails, the calculator does not go live.
See the calculations
- Distance 150 km · Fuel economy 6.5 L/100 km · Fuel price £2.05 per L · One way → Total cost £19.99
- Distance 150 km · Fuel economy 6.5 L/100 km · Fuel price £2.05 per L · Round trip → Total cost £39.98
- Distance 100 mi · Fuel economy 8 L/100 km · Fuel price £2.00 per L · One way → Total cost £25.75
- Distance 300 km · Fuel economy 15 km/L · Fuel price £1.90 per L · One way → Total cost £38.00
- Distance 100 mi · Fuel economy 30 mpg (US) · Fuel price £3.50 per US gal · One way → Total cost £11.67
- Distance 200 mi · Fuel economy 40 mpg (UK) · Fuel price £6.59 per UK gal · One way → Total cost £32.95
- Distance 100 mi · Fuel economy 30 mpg (US) · Fuel price £3.50 per US gal · One way → Total cost £11.67
- Distance 0 km · Fuel economy 6.5 L/100 km · Fuel price £2.00 per L · One way → Total cost £0.00
- Distance 100,000 km · Fuel economy 60 L/100 km · Fuel price £20.00 per L · Round trip → Total cost £2,400,000.00
- Distance 25 km · Fuel economy 5.8 L/100 km · Fuel price £2.10 per L · Round trip → Total cost £6.09
Changes
- : The cost per distance can now be shown per mile; the UK and US editions start with miles.
- : Separate default values and units for the UK and the US: distance in miles, fuel economy and fuel price from official national figures, and official sources for both.
- : Clearer help texts for the fields. Sources added and content reviewed.
- : Added an explanation, assumptions, worked examples and frequently asked questions.
- : First version.
Last reviewed: · How we build and check our calculators
Also useful
- Dutch Fuel Costs per YearEnter how far you drive per year and what the car uses, and see what that cost each year since 2006 at the average Dutch pump price of that year. Also in today's money.
- Dutch Fuel Price on a DateLook up the average Dutch pump price of petrol (Euro95), diesel or LPG on a date since 2006, and see how much more or less it costs now. Also in today's money.
- Dutch Number Plate CheckEnter a Dutch number plate to see what the RDW, the Dutch vehicle authority, records about the vehicle: make and model, year, weight and dimensions, fuel use, the MOT (APK) expiry date and open recalls. Then work out fuel, charging or depreciation costs with one click.
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