Fuel Cost Calculator
A 300 km trip at 7 L/100km uses 21 litres. At 1.80 per litre that costs 37.80. A fuel economy of 30 mpg (US) is 7.84 L/100km.
How to use
- Enter the distance and choose km or miles. Tick Round trip to double it.
- Enter your fuel economy and pick its unit: L/100km, km/L, mpg (US) or mpg (UK).
- Enter the fuel price and whether it is per litre, per US gallon or per UK gallon. The cost and fuel needed update at once.
How it works
Everything is converted to kilometres, litres and a price per litre. Fuel used = distance in km × L/100km ÷ 100. Cost = fuel used × price per litre.
Fuel economy conversions: L/100km = 100 ÷ (km/L). For mpg, L/100km = 235.215 ÷ mpg (US) or 282.481 ÷ mpg (UK).
The US gallon is 3.785411784 litres, the UK (imperial) gallon is 4.54609 litres, and one mile is 1.609344 km, all exact.
The result is an estimate. Real fuel use changes with speed, load, traffic and weather.
Fuel economy equivalents
| L/100km | km/L | mpg (US) | mpg (UK) |
|---|---|---|---|
| 5 | 20.0 | 47.0 | 56.5 |
| 7 | 14.3 | 33.6 | 40.4 |
| 10 | 10.0 | 23.5 | 28.2 |
| 15 | 6.7 | 15.7 | 18.8 |
FAQ
Why is mpg different in the US and UK?
The gallons are different sizes. A UK gallon is about 20% bigger, so the same car has a higher mpg figure in the UK than in the US.
Is a lower L/100km better?
Yes. L/100km measures fuel used, so lower is better. mpg and km/L measure distance per fuel, so higher is better.
How do I find my car's fuel economy?
Fill the tank, reset the trip meter, drive normally, then fill up again. Divide litres added by distance driven and multiply by 100 for L/100km.
Does it include tolls or parking?
No, only fuel. Add other trip costs yourself.