About the Fuel Cost Calculator
Before a long drive, a new commute or a holiday by car, it helps to know what the fuel will cost. It is also the fairest way to share costs with friends or colleagues who ride along, and a useful way to compare driving with the train, a coach or a flight. The arithmetic is straightforward, but it depends on units that differ from country to country: Americans measure fuel economy in miles per US gallon and pay by the gallon, British drivers use miles per imperial gallon but pay by the litre, and most of the world uses litres per 100 kilometres.
This fuel cost calculator handles all three. Choose US, UK or metric units, enter the distance, your vehicle's fuel economy and the fuel price, and it gives the cost of the journey, the fuel used, the cost per mile or kilometre, and — if you are sharing — the cost per person. Tick return journey to include the drive back.
How to Use the Fuel Cost Calculator
Choose the units you use.
Enter the distance one way, in miles or kilometres.
Enter the fuel economy: miles per gallon, or litres per 100 km.
Enter the fuel price: per US gallon in the US, per litre in the UK and elsewhere.
Tick return journey if you will drive back, and enter the number of people sharing the cost.
How Fuel Cost Is Worked Out
US fuel (gal) = miles ÷ mpg
cost = gallons × price per gallon
UK fuel (L) = miles ÷ mpg × 4.546
cost = litres × price per litre
Metric fuel (L) = km × L/100 km ÷ 100
cost = litres × price per litreStep-by-Step Example
A 300 mile trip in a 30 mpg car, with fuel at 3.50 a gallon.
Fuel: 300 ÷ 30 = 10 gallons
Cost: 10 × 3.50 = 35.00
Per mile: 35.00 ÷ 300 = 11.67 cents
Return: 2 × 35.00 = 70.00, or 35.00 each for two peopleA 500 km trip at 6.5 L/100 km, with fuel at 1.80 a litre.
Fuel: 500 × 6.5 ÷ 100 = 32.5 litres
Cost: 32.5 × 1.80 = 58.50A 200 mile trip in the UK at 45 mpg, with fuel at 1.45 a litre.
Fuel: 200 ÷ 45 = 4.44 gallons × 4.546 = 20.2 litres
Cost: 20.2 × 1.45 = 29.30Finding Your Car's Fuel Economy
The official figure is in the owner's manual, on the manufacturer's website or on the window sticker of a new car. Many cars also show average economy on the dashboard trip computer. The most accurate number, though, is your own: fill the tank, drive normally, fill it again, and divide the distance by the fuel added. The MPG calculator does this for you. Real-world figures are often 10 to 20 percent worse than official ones, so using your own figure gives a far more reliable estimate.
What Changes Your Fuel Use
Speed: fuel use rises sharply above about 55 to 60 mph, or 90 to 100 km/h, because air resistance increases with the square of speed. Driving at 70 mph instead of 80 can save around 10 to 15 percent.
Driving style: smooth acceleration and early braking use less fuel than sudden starts and stops.
Traffic and short trips: stop-start traffic and cold engines are the least efficient conditions of all.
Load and drag: roof boxes, bike racks and heavy loads increase consumption, as do open windows at speed.
Tyres: under-inflated tyres increase rolling resistance.
Air conditioning and weather: air conditioning, heating a cold engine and winter fuel blends all add a little.
Sharing Fuel Costs Fairly
For a trip with friends, the simplest approach is to split the fuel equally between everyone in the car, including the driver. Some groups also include tolls and parking in the shared cost, and some let the driver off a share in return for doing the driving and providing the car. For regular lift-sharing to work, many people use a set rate per mile or kilometre, which the cost per distance figure gives you.
Fuel Is Only Part of the Cost of Driving
Fuel is the cost people notice at the pump, but it is not the whole cost of a car. Insurance, tax, servicing, tyres, parking and depreciation often add up to more than the fuel. Official mileage allowances, such as the rates employers pay for business driving, are set well above fuel cost for this reason. When comparing driving with public transport, fuel is the fair figure only if you would own the car anyway.
Diesel, Petrol and Electric
Diesel usually costs a little more per litre or gallon than petrol, but diesel engines typically travel 20 to 30 percent further on the same amount of fuel, so the cost per mile is often lower on long motorway journeys. Hybrids save most in town, where they can run on electric power at low speeds. For a fully electric car, the cost depends on the price of electricity and where you charge — home charging overnight is usually far cheaper per mile than petrol, while rapid public chargers can cost much more. The EV charging cost calculator covers that case.
Understanding Your Result
Fuel cost is the total cost of the fuel for the journey.
Fuel used gives the gallons or litres and the total distance.
Cost per distance gives the fuel cost per mile or kilometre and per 100.
Per person divides the cost between the people sharing.
Worth knowing explains why real consumption is often higher.
When Should You Use This Calculator?
Planning a holiday or weekend away by car.
Sharing costs with passengers.
Comparing driving with the train or a flight.
Working out a commute before taking a new job.
Budgeting fuel for a delivery round or business trip.
Common Mistakes
Mixing US and UK gallons.
Forgetting the return journey.
Using the official figure instead of real-world economy.
Entering the price per litre as a price per gallon.
Ignoring tolls and parking when sharing costs.