Is this UK MPG or US MPG?

UK imperial MPG. US gallons are smaller, so US MPG figures look higher for the same car. Do not mix the two.

Should I use the handbook MPG?

Handbook and WLTP figures are useful for comparing similar cars in the same test cycle, but real ownership economy is usually lower. Prefer your own logged MPG for budgeting.

Does it work for hybrids and EVs?

For petrol and diesel hybrids, enter the combined MPG you actually achieve. For pure EVs, use electricity cost per mile instead — this tool is for liquid fuel.

Where do I find today’s fuel price?

Check the pump, supermarket apps, or comparison sites for your postcode. Prices change daily and can differ by 10p+/litre on the same street.

Free UK calculator

Fuel cost calculator

Estimate what a journey will cost using UK imperial MPG and the price you actually pay at the pump. Built for British drivers — gallons, litres and pence converted correctly.

Distance (miles)Economy (UK MPG)Fuel price (£/litre)

Estimated journey cost

£29.30

About 20.2 litres · £0.146 per mile

Formula: miles ÷ UK MPG × 4.54609 × £/litre

How the UK fuel cost formula works

UK car economy is usually quoted in imperial miles per gallon (MPG). One UK gallon equals 4.54609 litres. So fuel used in litres is: distance ÷ MPG × 4.54609. Multiply that by your price per litre to get the journey cost.

Always use a real-world MPG if you can — the trip computer average, or a brim-to-brim tank calculation — rather than the optimistic WLTP brochure figure. Short trips, cold weather, heavy loads and motorway speeds all change the result.

This calculator does not include parking, congestion charge, Ultra Low Emission Zone (ULEZ) fees or time spent in traffic. Use it to compare cars or routes, not as a receipt.

Worked examples

London to Manchester (~200 miles) in a 45 MPG hatchback

At £1.45/litre: 200 ÷ 45 × 4.54609 × 1.45 ≈ £29.30. If economy drops to 38 MPG in winter traffic, the same trip costs closer to £34.70.

Weekly commute of 80 miles in a 55 MPG diesel

At £1.52/litre: 80 ÷ 55 × 4.54609 × 1.52 ≈ £10.05 per week, or roughly £522 a year if you drive that every week.

Comparing two used cars before buying

Run both cars at your annual mileage and local fuel price. A 10 MPG difference on 10,000 miles a year is often worth hundreds of pounds — sometimes more than a cheaper purchase price saves.

Frequently asked questions

Is this UK MPG or US MPG?: UK imperial MPG. US gallons are smaller, so US MPG figures look higher for the same car. Do not mix the two.
Should I use the handbook MPG?: Handbook and WLTP figures are useful for comparing similar cars in the same test cycle, but real ownership economy is usually lower. Prefer your own logged MPG for budgeting.
Does it work for hybrids and EVs?: For petrol and diesel hybrids, enter the combined MPG you actually achieve. For pure EVs, use electricity cost per mile instead — this tool is for liquid fuel.
Where do I find today’s fuel price?: Check the pump, supermarket apps, or comparison sites for your postcode. Prices change daily and can differ by 10p+/litre on the same street.

Related tools and guides

MotorTools calculators give planning estimates only. Confirm figures against GOV.UK, your V5C, handbook or a qualified garage before buying, renewing tax or carrying out work.