Fuel Cost Per Mile Calculator
Turn your MPG and the price at the pump into a real cost per mile, so you can price jobs and quote for travel with confidence.
Imperial gallons.
Per litre.
Advanced options
Fuel cost per mile
14.65p
- Litres per mile
- 0.1
- Cost per 100 miles
- £14.65
- Annual fuel cost
- £1,464.85
Fuel only. This is a running cost, not a tax-deductible mileage rate.
Where do I find my real MPG?
Most cars show a long-term average on the dashboard. Otherwise, fill the tank, note the mileage, refill it later and divide the miles driven by the gallons used (litres ÷ 4.54609).
What this means
Cost per mile is what the fuel alone costs you to drive one mile. It is a business cost, not a tax figure — it does not tell you what you can claim, and it is usually lower than HMRC's approved mileage rate because that rate also covers insurance, servicing, tyres and depreciation.
Use it to check whether a job that involves travel is actually worth taking, and to see what a more efficient vehicle would save over a year.
Quick answers
- How do I convert MPG to pence per mile?
- Divide 4.54609 by your MPG to get litres per mile, then multiply by the pump price per litre and by 100 to get pence.
- Why is UK MPG different from US MPG?
- UK MPG is based on the imperial gallon (4.54609 litres); US MPG uses the smaller US gallon (about 3.785 litres), so identical fuel economy shows a higher number in US MPG.
- Is fuel cost per mile the same as a mileage claim rate?
- No. It is only the fuel element. A mileage claim rate, such as HMRC's approved amount, also covers running costs like insurance and depreciation.
- Does a higher MPG always mean cheaper motoring?
- Not necessarily — the fuel price per litre matters just as much. A car with better MPG on more expensive fuel can cost about the same per mile as a thirstier car on cheaper fuel.
Feed this into your pricing
Fuel is only part of the cost of a mile: tyres, servicing, insurance and depreciation all add to it before you have earned anything.
If travel is a large part of a job, check the quote still works once the round trip is costed in.
You may also find useful
- HMRC Business Mileage CalculatorApproved mileage for your own car, van, motorcycle or bicycle at HMRC rates.
- Company Car Advisory Fuel Rate CalculatorCompany car fuel reimbursement using HMRC's quarterly advisory fuel rates.
- Cash Flow Runway CalculatorHow many months your cash lasts at your current rate of spending.
How we calculated it
UK MPG is measured in imperial gallons, where one gallon is 4.54609 litres. So:
litres per mile = 4.54609 ÷ MPG
fuel cost per mile = litres per mile × price per litre
Journey and annual costs are simply the cost per mile multiplied by the miles you enter.
Assumptions
- MPG is in imperial gallons, as used on UK vehicles.
- The fuel price stays the same across the miles you enter.
- Fuel only — no servicing, tyres, insurance, tax or depreciation.
- Real-world MPG is usually lower than the official figure, so use your own average if you have one.
How this calculator works
A car doing 45 MPG uses roughly 0.101 litres per mile. At £1.45 a litre, that is about 14.7p per mile in fuel. Halving the fuel price or doubling the MPG halves the cost per mile — both matter equally.
UK MPG uses the imperial gallon (4.54609 litres). US MPG uses the smaller US gallon (about 3.785 litres), so a US MPG figure looks higher than a UK MPG figure for the exact same fuel economy — always check which gallon a quoted MPG figure is using before you compare cars.
For tax purposes, keep this separate from mileage rates: approved mileage rates apply to your own vehicle and advisory fuel rates apply to company cars.
Worked examples
45 MPG at £1.45 a litre
Litres per mile = 4.54609 ÷ 45 = 0.101. Cost per mile = 0.101 × £1.45 = about 14.65p. Over 10,000 annual miles that is roughly £1,464.85 in fuel.
35 MPG at £1.50 a litre
Litres per mile = 4.54609 ÷ 35 = 0.1299. Cost per mile = 0.1299 × £1.50 = about 19.48p. Over 10,000 annual miles that is roughly £1,948.32.
60 MPG at £1.60 a litre
Litres per mile = 4.54609 ÷ 60 = 0.0758. Cost per mile = 0.0758 × £1.60 = about 12.12p. Over 8,000 annual miles that is roughly £969.83 — showing how much a more efficient vehicle saves even at a higher fuel price.
Key terms explained
- Imperial gallon
- The gallon used for UK MPG figures, equal to 4.54609 litres.
- US gallon
- A smaller unit (about 3.785 litres) used for US MPG figures, which is why US MPG numbers look higher for the same real fuel economy.
- Litres per mile
- The amount of fuel used to travel one mile, found by dividing 4.54609 by the MPG figure.
Common mistakes
Comparing a US MPG figure with a UK MPG figure
US and UK gallons are different sizes, so the same car can show a noticeably higher MPG figure in US units. Always confirm which gallon a figure is quoted in before comparing.Using the fuel price per gallon instead of per litre
This calculator expects the price per litre, which is how UK forecourts price fuel. Entering a per-gallon price by mistake will overstate the cost per mile several times over.Treating fuel cost per mile as a tax-deductible rate
This is a running-cost figure, not a claimable rate. For tax-free mileage payments on your own vehicle use the mileage calculatorinstead.
Common questions
How do I work out fuel cost per mile?
Divide 4.54609 by your MPG to get litres per mile, then multiply by the price per litre. That gives the fuel cost of driving one mile.
Why 4.54609?
UK MPG uses imperial gallons, and one imperial gallon is 4.54609 litres. US gallons are smaller, which is why US MPG figures look higher for the same car.
Is fuel cost per mile the same as the HMRC mileage rate?
No. HMRC's approved mileage rate also covers insurance, servicing and depreciation, so it is normally well above the pure fuel cost.
Can I use this for an electric vehicle?
No. This calculator works from MPG and a price per litre. Electric running costs are based on pence per kWh and efficiency in miles per kWh instead.
Should I use the official MPG or my own?
Use your own average if you have one. Official figures are measured under test conditions and real-world economy is usually lower.
Does the fuel price include VAT?
Pump prices include VAT. If you are VAT registered and reclaiming VAT on fuel, your net cost per mile will be lower.
What if a supplier quotes MPG in US gallons?
Convert it first. A US MPG figure divided by 1.20095 gives an approximate UK imperial MPG figure, because a US gallon is smaller than a UK gallon.
Last reviewed: 7 September 2026. This calculator is information only and is not tax, accounting or financial advice.