Fuel cost calculator

What a journey costs in fuel, and each person’s share.

Formula Everyday

Fuel cost

Rounded for display

Cost per person: ≈ 27.63
Fuel used: 16.25 L
Cost per km: ≈ 0.111

How it works

The fuel used is worked out from the distance and your car’s consumption, then multiplied by the price. Turn on “return trip” to double the distance.

US and UK miles per gallon are different, because the US gallon is 3.785411784 litres and the UK (imperial) gallon 4.54609 litres. In the UK fuel is sold by the litre, so the UK mode converts gallons to litres.

Real consumption depends on speed, traffic, load and weather. Results are in whatever currency you enter the price in.

Formula

Litres = km × L/100 km ÷ 100
US gallons = miles ÷ US mpg
Litres (UK) = miles ÷ UK mpg × 4.54609
Cost = fuel used × price

Worked example

A 250 km trip in a car using 6.5 L/100 km needs 250 × 6.5 ÷ 100 = 16.25 litres. At 1.70 per litre that costs 27.63. In US units, 150 miles at 30 mpg is 5 gallons, or 16.00 at 3.20 a gallon.

Questions people ask

How do I convert mpg to L/100 km?

Divide 235.215 by US mpg, or 282.481 by UK mpg. So 30 US mpg is about 7.84 L/100 km.

Why are UK and US mpg different?

The imperial gallon is about 20% larger than the US gallon, so the same car shows a higher mpg figure in the UK.