How to calculate fuel cost for a trip
Use distance, fuel economy and the price of the fuel you expect to buy.
By the TripFuel team · Updated November 3, 2026
Use consistent units
For a trip measured in miles and fuel economy measured in US miles per gallon, divide distance by MPG to estimate US gallons. Multiply that fuel volume by the price per US gallon. A 250-mile trip at 30 MPG uses 250 ÷ 30 = 8.333… US gallons. At $3.50 per gallon, the estimated cost is $29.17 after rounding to cents.
The metric calculation
With kilometres and litres per 100 kilometres, multiply distance by the consumption rate and divide by 100. For 400 km at 7 L/100 km, estimated consumption is 28 litres. At 1.60 per litre, the cost is 44.80 in the currency you use. TripFuel converts the selected units internally, so you can combine a distance in miles with an economy value in L/100 km without manually converting first.
Know what the estimate includes
This calculation estimates fuel only. It does not include tolls, parking, insurance, depreciation, meals or accommodation. Fuel price is entered by you; there is no automatic live-price or map lookup. Use a realistic average price for the journey, and remember that traffic, weather, speed, load and terrain can change actual consumption. The currency selector labels the result and does not apply exchange rates.
Put the example into practice with the free fuel cost calculator.