Fuel Cost Calculator UK 2026
This fuel cost calculator turns your mileage, MPG and pump price into an annual fuel cost and a clear pence-per-mile figure for petrol or diesel. Use the fuel cost calculator below to see what your driving really costs — then add it to your wider household budget.
How the fuel cost is worked out
Annual fuel cost = (miles ÷ MPG) × 4.546 litres per gallon × pump price. The pence-per-mile figure is that total divided by your annual miles — handy for working out the cost of a commute or a specific journey.
How much does fuel cost to run a car in the UK in 2026?
Fuel is one of the biggest running costs of owning a car. Through 2026 UK pump prices have broadly sat in the region of £1.35 to £1.45 per litrefor both petrol and diesel, though the exact figure moves with wholesale oil markets and differs from one forecourt to the next. Those numbers are illustrative only — for today’s confirmed average, check RAC Fuel Watch before you budget. This fuel cost calculator turns whatever pump price you enter into a cost per mile and an annual fuel bill, so the figure you see reflects the price you actually pay.
What makes fuel spending hard to picture is that it depends on three things at once: how far you drive, how efficient your car is (its MPG), and the price per litre on the day. A driver covering 5,000 miles a year in a frugal hybrid spends a fraction of what a 20,000-mile commuter in a thirsty petrol does, even at the same pump price. Working the cost out per mile is the fairest way to compare cars, journeys and fuel types.
Fuel is only part of the cost of motoring, which also includes insurance, road tax, servicing and depreciation — and it sits alongside all your other household outgoings. To see driving costs next to your energy, water and council tax, use the household bills calculator, and to check how much take-home pay is left to cover the car after tax, try the salary calculator.
How cost per mile is worked out
Every fuel cost calculation comes back to one formula. UK cars measure economy in miles per gallon (MPG), but you buy fuel in litres, so the sum has to convert between the two using the fact that one imperial gallon is 4.546 litres:
annual fuel cost = (miles ÷ MPG) × 4.546× pump price (£/litre)
Dividing your annual mileage by your MPG gives the number of gallons burned; multiplying by 4.546 converts that to litres; and multiplying by the pump price in pounds gives the cost. To get cost per mile, simply drop the mileage: cost per mile = 4.546× pump price ÷ MPG.
Worked example
Take a typical petrol car returning 40 mpg with the pump price at £1.40 a litre. The cost per mile is 4.546 × 1.40 ÷ 40 = about 15.9p per mile. Drive 12,000 miles a year and the fuel bill comes to 15.9p × 12,000 = roughly £1,909. Swap in a 60 mpg hybrid at the same pump price and the cost per mile drops to about 10.6p — cutting the same 12,000-mile bill to around £1,273. That gap is the whole reason MPG matters.
Annual fuel cost by mileage and MPG
The table below shows the estimated annual fuel cost for four common mileages against three efficiency levels, all at a pump price of £1.40 per litre. Read down a column to see how much a more efficient car saves at your mileage; read across a row to see how quickly costs climb as you drive further. Enter your own MPG, mileage and today’s pump price in the calculator above for a figure tailored to your car.
| Annual mileage | 40 mpg | 50 mpg | 60 mpg |
|---|---|---|---|
| 5,000 miles | £796 | £636 | £530 |
| 8,000 miles | £1,273 | £1,018 | £849 |
| 12,000 miles | £1,909 | £1,527 | £1,273 |
| 20,000 miles | £3,182 | £2,546 | £2,121 |
Illustrative at £1.40/litre using annual cost = (miles ÷ MPG) × 4.546 × price. Source: RAC Fuel Watch for today’s pump price.
The spread is striking. A 20,000-mile driver in a 40 mpg car spends over £3,182 a year on fuel alone, while a 5,000-mile driver in a 60 mpg hybrid spends barely £530. Because the pump price changes constantly, treat these as a guide and re-run the calculator whenever prices move — a 10p-per-litre swing changes the whole table.
Petrol vs diesel vs hybrid
Which fuel is cheapest to run depends less on the pump price and more on how many miles you cover and where. The three mainstream options — petrol, diesel and hybrid — each suit a different kind of driver, and their typical MPG ranges explain why.
| Fuel type | Typical economy | Cost per mile* | Best for |
|---|---|---|---|
| Petrol | 45–55 mpg | 12.7p | Cheapest to buy, higher pump price per litre |
| Diesel | 50–65 mpg | 11.6p | Best for high-mileage motorway drivers |
| Hybrid | 60+ mpg | 9.8p | Strong in town, no plug-in needed |
*Cost per mile at £1.40/litre on the mid-point MPG shown. Diesel usually costs a few pence more per litre than petrol, which narrows its per-mile advantage.
Petrol cars are cheapest to buy and returning 45–55 mpg suit most low- and medium-mileage drivers. Diesel engines return 50–65 mpg and come into their own on long motorway journeys and high annual mileages, where the extra economy outweighs the slightly higher pump price. Hybrids can exceed 60 mpg and are strongest in stop-start town driving, recovering energy under braking without needing to be plugged in. Remember that fuel is only one line in the running-cost total — insurance, servicing and depreciation can easily outweigh the per-mile fuel difference, so compare the whole cost of ownership rather than economy alone.
The 45p mileage allowance and fuel duty
If you drive your own car for work, you can be reimbursed tax-free under HMRC’s Approved Mileage Allowance Payments (AMAP). The headline rate is 45p per mile for the first 10,000 business miles in a tax year, then 25p per mile after that. The rate is designed to cover not just fuel but wear, servicing, insurance and depreciation, which is why it is well above the pure fuel cost per mile.
| Vehicle | First 10,000 miles | Over 10,000 miles |
|---|---|---|
| Car or van | 45p per mile | 25p per mile |
| Motorcycle | 24p per mile | 24p per mile |
| Bicycle | 20p per mile | 20p per mile |
Source: GOV.UK — Travel, mileage and fuel rates and allowances. If your employer pays less than these rates, you can claim tax relief on the shortfall.
If you drive a company carrather than your own, a different set of figures applies: HMRC’s Advisory Fuel Rates, reviewed quarterly, set the pence-per-mile you can reclaim for business fuel or repay for private mileage.
A large slice of what you hand over at the pump is tax. Fuel duty is a flat 52.95p per litre — a fixed amount charged regardless of the oil price — and on top of that 20% VAT is added to the duty and the wholesale product cost. On a £1.40 litre that is roughly 52.95p of duty plus about 23p of VAT — more than half the price going to the Treasury before the retailer sees a penny.
Source: GOV.UK — Fuel Duty
Ways to cut your fuel costs
Because fuel spending is mileage × efficiency × price, you can attack all three levers. Some savings come from how you drive, some from keeping the car in good shape, and some from simply buying fuel more cheaply.
- Drive smoothly — gentle acceleration and anticipating traffic can cut fuel use by 10% or more.
- Ease off the motorway speed: driving at 70mph uses noticeably less fuel than 80mph.
- Keep tyres correctly inflated — under-inflated tyres increase rolling resistance and fuel use.
- Remove roof bars, roof boxes and unnecessary weight when you are not using them.
- Service the car regularly and use the correct engine oil to keep it running efficiently.
- Combine short trips so the engine warms up once, rather than several cold, thirsty starts.
- Use a fuel price app or RAC Fuel Watch to find the cheapest local forecourt before you fill up.
If your mileage is high and you can charge at home, switching to an electric car can cut the per-mile energy cost dramatically, because home electricity is far cheaper per mile than petrol or diesel. You can model that home-charging cost against your other energy use with the electricity bill calculator or the combined gas and electric bill calculator. And because a car is a fixed monthly commitment much like council tax, it is worth reviewing fuel spending next to your council tax calculator figure when you plan the year’s budget.
Fuel cost calculator: frequently asked questions
Everything you need to know about working out cost per mile, comparing petrol, diesel and hybrid MPG, the 45p mileage allowance and how to pay less for fuel in 2026.