Practical guide

How to calculate the cost of a car journey

Miles, MPG, fuel price, tolls and cost sharing explained.

1. Convert MPG into fuel used

Litres = miles ÷ MPG × 4.54609

2. Convert fuel into pounds

Fuel cost = litres × pence/litre ÷ 100

3. Add route costs

Add tolls and parking separately. For a broader ownership cost, use cost per mile.

Open journey cost calculator →


Last reviewed: 31 August 2026. See also methodology and sources.