Free calculator

Fuel cost calculator

Work out what it really costs to drive, for a single journey or a whole year. Put in the miles, the car's economy and what you pay for fuel, and see the cost per mile, the fuel used and the total. Works for petrol, diesel and electric. Free, no sign-up.

What are you working out?

A single journey A year of driving

Fuel type

Fuel economy (MPG) The higher this is, the cheaper the car is to run.

Petrol price (pence per litre) Edit to the price you actually pay.

Distance (miles) One way; we'll show the return trip too.

Petrol vs diesel vs electric, over a year

10,000 miles a year, each on typical economy and fuel prices: petrol at 45 MPG, diesel at 55 MPG, and an EV at 3.5 miles per kWh charged at home.

Worked example: a year of fuel at 10,000 miles
	Petrol	Diesel	Electric
Assumed economy	45 mpg	55 mpg	3.5 mi/kWh
Assumed price	140p/l	147p/l	24.5p/kWh
Cost per mile	14.1p per mile	12.2p per mile	7p per mile
Cost a year	£1,414.34	£1,215.05	£700

On these figures the electric car saves about £714.34 a year in fuel against petrol, but only because it's charged at home. Swap in a public rapid-charger rate and that gap narrows fast, sometimes to nothing. Diesel edges petrol on economy but costs more per litre and faces tighter Clean Air Zone rules in some cities. There's no single winner; it depends on your mileage, where you charge or fill up, and what you pay. Change the numbers above to match your own driving.

Working out what a car costs to drive

The pump price gets all the attention, but it's the wrong number to judge a car on. Two cars filling up at the same forecourt can cost wildly different amounts to run, because what actually matters is how far each one goes on that fuel. A thirsty petrol doing 30 to the gallon burns twice as much as an economical one doing 60, mile for mile, however cheap the petrol looks on the pole. The figure worth knowing is the cost per mile, and that's the first thing the calculator above works out.

For petrol and diesel the sum is simple once you've got the car's real MPG: every mile uses a gallon divided by the MPG, a gallon is 4.54609 litres, and you multiply the litres by the pump price. The catch is the word "real". The MPG on the window sticker is measured in a lab, and almost nobody sees it on the road: town driving, short cold-engine trips and a heavy right foot all drag it down. Use the figure off your trip computer if you have it, and if you're buying, knock the brochure number down a fair bit for an honest estimate.

Electric cars change the shape of the sum. Efficiency is measured in miles per kWh instead of miles per gallon, and the "fuel price" is your electricity unit rate. Charge at home overnight and the cost per mile is usually a fraction of petrol, which is where the "EVs are cheap to run" line comes from. But lean on public rapid chargers and the per-kWh price can be two or three times a home rate, enough to wipe the saving out. The honest way to compare is to put in the price you'll actually pay to charge, not the best-case home figure.

Whatever the car, fuel is only one slice of the running cost. Tax, insurance, servicing, tyres and depreciation all pile on top, and some of those swing hugely between models. It's worth checking the road tax and, if you drive into a city, whether the car faces a ULEZ or Clean Air Zone charge before you commit. And because every one of these sums leans on the car being what the advert says, it's worth confirming that first: the free MOT check sanity-tests the mileage and last test, and the full report confirms the registered fuel type, engine and spec, so the economy you're banking on is the economy you'll get.

Fuel cost calculator: common questions

How is the cost of fuel for a journey worked out?

It comes from three numbers: how far you're driving, how many miles the car does per gallon (or per kWh for an electric car), and what you pay for fuel. Divide the miles by the MPG to get gallons, turn that into litres (a UK gallon is 4.546 litres) and multiply by the pump price. For an electric car it's the miles divided by the miles per kWh, times your electricity unit rate. This calculator does all of that from whatever figures you put in.

What MPG or miles per kWh should I use?

Use what the car actually returns, not the brochure figure; real-world economy is nearly always lower than the official number. Most petrol cars manage somewhere between 35 and 50 MPG in mixed driving, diesels a bit more, and an electric car typically covers 3 to 4 miles per kWh. Your trip computer is the honest source; if you don't know it yet, the defaults here are sensible starting points.

Is an electric car really cheaper to run than petrol?

On fuel alone, usually yes, if you charge at home. At a typical home electricity rate an EV often costs a third to a half of the fuel of an equivalent petrol car per mile. That flips if you rely on public rapid chargers, which can cost two to three times the home rate and sometimes rival petrol. Put your real charging price into the calculator to see where you land. Remember fuel is only part of the running cost: tax, insurance and depreciation matter too.

What's the difference between the pump price and the cost per mile?

The pump price is per litre; the cost per mile is what actually leaves your pocket for every mile you drive, once you factor in how thirsty the car is. A car doing 30 MPG and one doing 60 MPG pay the same at the pump but the first costs twice as much per mile. Cost per mile is the fairest way to compare two cars, or petrol against electric.

Does the car's real fuel economy match the advert?

Not always. A car that's been poorly maintained, driven hard or has a mechanical issue can return far worse economy than its official figure, and adverts quote the flattering number. Our £5.00 report confirms the car's registered fuel type, engine and spec from the DVLA record, and its MOT-recorded mileage history, so you know what you're actually buying before you trust an economy claim.