Trip Fuel Cost Calculator: Gas Cost for Any Drive

Enter your trip distance, your car's fuel economy and the fuel price to see how much fuel you'll use and what it costs. You can also split the cost between passengers. Works with metric or imperial units.

How to use the calculator

Enter the one-way distance of your trip and choose kilometres or miles. Add your car's fuel economy in the unit you know: litres per 100 km, km per litre, or miles per gallon (US or UK gallons are different sizes, so pick the right one). Then enter the fuel price and say whether it is per litre, per US gallon or per UK gallon.

Tick Round trip if you are coming back the same way, and set how many people are splitting the cost. The total cost, cost per person, fuel needed and cost per km or mile update straight away.

The formula

The calculator first converts everything to litres and kilometres. Fuel used in litres = distance in km × L/100 km ÷ 100. For km per litre it is distance ÷ km/L. For MPG it is miles ÷ MPG × litres per gallon (3.785 for a US gallon, 4.546 for a UK gallon).

The price is converted to a price per litre in the same way, then total cost = litres used × price per litre. Cost per person is the total divided by the number of people, and cost per km or mile is the total divided by the distance driven.

Worked example

A 300 km drive in a car that uses 6 L/100 km needs 300 × 6 ÷ 100 = 18 litres. At 1.80 per litre that costs 18 × 1.80 = 32.40, or about 0.108 per kilometre. Make it a round trip and the cost doubles to 64.80.

In US units, a 500 mile trip at 25 MPG uses 500 ÷ 25 = 20 US gallons (75.71 litres). At $3.50 a gallon that is $70.00, or $35.00 each for two people.

Tips for a realistic estimate

This is an estimate. Real consumption changes with speed, traffic, hills, air conditioning, roof boxes and load. Motorway driving above 110 km/h (70 mph) can use 10–20% more fuel than the official figure. Use the average shown on your trip computer if you have one, and add a small buffer for detours.

For electric cars, this tool doesn't apply directly; use energy per distance and electricity price instead.

Frequently asked questions

What is the difference between US and UK MPG?

A UK (imperial) gallon is 4.546 litres while a US gallon is 3.785 litres. So 40 MPG in UK gallons is only about 33 MPG in US gallons. Choose the unit that matches where your figure came from.

How do I convert MPG to L/100 km?

For US MPG, divide 235.21 by the MPG figure; for UK MPG, divide 282.48 by it. For example, 30 US MPG is about 7.8 L/100 km.

How should we split fuel costs on a shared trip?

The simplest fair method is to divide the total fuel cost equally among everyone in the car, including the driver. Some groups exclude the driver or add tolls and parking; you can add those separately.

Why does my actual fuel bill differ from the estimate?

Official economy figures come from controlled tests. Speed, weather, cargo, tyre pressure and idling all change real use, and fuel prices vary between stations along the route.