Estimate what a trip will cost in fuel, in US or metric units.
The fuel cost of any journey comes down to three things: how far you are driving, how thirsty your vehicle is, and what fuel costs where you fill up. Put those together and you get a reliable estimate for budgeting a road trip, splitting travel costs with friends, or comparing driving against other transport.
The two formulas look different because the world measures fuel economy in two ways. In the US, economy is miles per gallon — a bigger number is better — so you divide distance by MPG to find gallons used. In most of the world, economy is litres per 100 km — a smaller number is better — so you scale the distance to hundreds of kilometres and multiply by the consumption rate. The calculator switches formulas automatically when you change the unit toggle.
Beyond the trip total, the calculator shows the cost per unit of distance. This is a handy running figure: once you know your car costs, say, 15 cents a mile in fuel, you can price any journey in your head. It also makes vehicles comparable — a car that costs half as much per mile will save real money over a year of commuting.
For the best result, use your own real-world economy rather than the manufacturer's sticker figure, which is measured in ideal conditions. City traffic, cold starts, air conditioning, roof boxes and heavy loads all push consumption up. If you track a few tanks of fuel you will know your true average, and this calculator will turn it into an accurate trip budget.
Work out how much fuel the trip uses, then multiply by the fuel price. In US units: distance ÷ MPG × price per gallon. In metric: distance ÷ 100 × litres per 100 km × price per litre.
Both measure fuel economy. MPG (miles per gallon) is higher-is-better — more miles from each gallon. L/100km (litres per 100 kilometres) is lower-is-better — fewer litres to cover 100 km. This calculator handles either.
Drive smoothly, keep tyres properly inflated, remove excess weight and roof racks, and avoid high speeds where air resistance spikes consumption. Combining trips and maintaining the engine also improves real-world economy.
Enter the total distance you will drive. For a round trip, double the one-way distance, or simply put in the full there-and-back figure.
Manufacturer economy figures are measured in ideal conditions. City driving, cold weather, air conditioning, traffic and a heavy load all raise real consumption, so use your own observed economy for the most accurate estimate.