Fuel Cost Calculator
Trip fuel cost, cost per person and fuel economy from a fill-up
Runs in your browser · nothing is uploaded
Updated 2026-10-04The starting numbers (300 km one way, 12 km/L, 1.70 per liter) are only an example. Pick miles, mpg (US or UK) or gallons below if you use them. Live fuel prices are not connected, so enter the price at your station and your own car economy.
Trip type
Round trip doubles the distance you enter. Add tolls below for either trip type.
Distance of the outbound leg in km, up to one decimal place.
In km/L. US mpg uses the 3.785 L US gallon, UK mpg the 4.546 L imperial gallon. Your dashboard average is the most realistic number.
Any currency, up to two decimals. Use the price shown at the pump.
Tolls for the one-way trip. Leave blank for zero.
From 1 to 20. Fuel and tolls are split evenly.
Fuel cost 42.50, total 42.50, per person 42.50
Result
- Total distance
- 300 km
- Fuel needed
- 25 L
- Fuel cost
- 42.50
- Total
- 42.50
- Per person
- 42.50
- Cost per km
- 0.142
The math with your numbers
- Fuel = 300 km at 12 km/L = 25 L
- Fuel cost = 25 L × 1.70 = 42.50
Prices are never fetched, so the result is only as good as the numbers you type. Currency is generic: use whatever you pay in, with two decimals. The cost is rounded once to the smallest unit, and the per-person share is rounded too, so shares times people can differ from the total by a cent or so. Real economy shifts with air conditioning, load and traffic. Toll discounts, parking and meals are not included. For the fuel economy mode, fill the tank fully both times for a reliable number.
What it is
Planning a long drive and wondering what the fuel will cost? Enter the one-way distance, your car’s fuel economy and the fuel price, and this calculator shows how much fuel you need and what it costs. Use the units you think in: kilometers or miles, km/L, L/100 km, US mpg or UK mpg, and a price per liter or per US or UK gallon, so a US driver can type 25 mpg and 3.50 a gallon, and a UK driver 45 mpg and 1.45 a litre. Pick Round trip or Holiday trip to double the distance, add the tolls for the whole journey, and split the total between everyone riding along. A second mode works backwards: give it the distance since your last fill-up and the liters it took to top up, and it returns your real km/L, L/100 km, US mpg and UK mpg and, with a price, the cost per kilometer or mile. Everything runs in your browser and no fuel price is looked up for you.
How to use
- Choose Trip fuel cost or Fuel economy at the top, and pick your distance, fuel economy and fuel units.
- For a trip, pick one way or round trip, then enter the one-way distance, the fuel economy and the price.
- Add any tolls (for a round trip, the total for both directions), and enter how many people share the cost.
- For fuel economy, enter the distance driven and the fuel added. A price is optional and adds the total and the cost per km or mile.
- Check the result table and the math lines to see exactly how each number was reached.
How it works
- Fuel needed = total distance ÷ fuel economy (km/L or mpg), or distance × L/100 km ÷ 100. Fuel cost = fuel × price per unit of fuel.
- Units are converted with the exact definitions: 1 mile = 1.609344 km, 1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L. US mpg counts US gallons and UK mpg imperial gallons, so 30 UK mpg is about 25 US mpg.
- Round trip uses twice the distance you enter. Tolls are added for either trip type.
- Per person = (fuel cost + tolls) ÷ people, rounded to the nearest cent.
- Fuel economy = distance driven ÷ fuel added, shown to two decimals as km/L, L/100 km, US mpg and UK mpg.
- Distance takes one decimal and is capped at 100,000 in the unit you pick. Economy and fuel take two decimals.
- Math runs on integers, and money is rounded once at the end, so there is no floating-point drift.
Examples
A round trip of 300 km each way at 12 km/L, with fuel at 1.70 per liter, tolls of 25.00 and four people.
| Item | Math | Result |
|---|---|---|
| Total distance | 300 × 2 | 600 km |
| Fuel needed | 600 ÷ 12 | 50 L |
| Fuel cost | 50 × 1.70 | 85.00 |
| Total with tolls | 85.00 + 25.00 | 110.00 |
| Per person | 110.00 ÷ 4 | 27.50 |
These prices are example numbers, not real fuel or toll prices.
Good to know
Real fuel economy moves with air conditioning, luggage, traffic and driving style, so the average on your dashboard, or a number you measured over two full fill-ups, beats the brochure figure. Toll discounts, parking and meals are not included. If you want to estimate them, add them to the toll box on a holiday trip.
FAQ
How is trip fuel cost calculated?
Divide the distance by your fuel economy in km/L to get the liters needed, then multiply by the price per liter. For 300 km at 12 km/L and 1.70 per liter you need 25 L, which costs 42.50.
Does the calculator know today's fuel prices?
No. Prices are never fetched, so type the price you see at the pump. The 1.70 in the box when the page opens is only an example.
How do I cost a return trip with tolls?
Choose round trip to double the distance, then enter the tolls for the whole journey. Tolls are added on one-way trips too, whatever you enter.
How is the cost split between people?
Fuel plus tolls is divided by the number of people, from 1 to 20, and rounded to the nearest cent. Shares times people can differ from the total by a cent or two.
Which currency does it use?
Any. The tool shows plain numbers with two decimals, so enter prices in the currency you pay in. Units are your choice — kilometers or miles, km/L, L/100 km, US mpg or UK mpg, and a price per liter, US gallon or UK gallon.
