Fuel Cost Calculator UK: Calculate Petrol, Diesel and Electric Costs

Use our fuel cost calculator to estimate how much a trip will cost in a petrol, diesel or electric car.

Enter your distance, vehicle fuel economy and the price you pay for fuel or electricity. You can then estimate the total cost, cost per mile and fuel or energy used.

For the most accurate result, use your car's real-world MPG or miles per kWh and the current price you expect to pay.

Fuel Cost Calculator UK

For a petrol or diesel car, the calculation is:

• Fuel cost = (Distance ÷ MPG) × 4.54609 × fuel price per litre

For an electric car:

• Electric cost = (Distance ÷ miles per kWh) × electricity price per kWh

The calculator gives an estimate. Your actual cost can vary because of traffic, driving style, weather, vehicle load, tyre pressures and real-world fuel economy.

For an electric car, the electricity price also depends on where you charge. Home charging and public charging can have very different rates.

How to Calculate Fuel Cost

You need three main figures:

• Your distance in miles

• Your vehicle's MPG, or miles per kWh for an electric car

• The fuel price per litre or electricity price per kWh

Enter these figures into the calculator to estimate the cost of your trip.

Petrol and diesel fuel cost formula

For petrol or diesel:

• Fuel used in litres = (Distance ÷ MPG) × 4.54609

• Fuel cost = Fuel used in litres × price per litre

For example, a 40 MPG car travelling 100 miles would use:

100 ÷ 40 × 4.54609 = 11.37 litres

At an example petrol price of £1.50 per litre:

11.37 × £1.50 = £17.05

The £1.50 price is an example, not a current UK average. Replace it with the price you actually pay.

Electric car cost formula

For an electric car:

• Electric cost = Distance ÷ miles per kWh × electricity price per kWh

For example, if an electric car achieves 3.5 miles per kWh and electricity costs 30p per kWh:

100 ÷ 3.5 = 28.57 kWh

28.57 × £0.30 = £8.57

This is an energy-cost calculation. Actual charging costs can be higher depending on charging losses, the charging network and the tariff you use.

Petrol Cost Calculator

A petrol cost calculator estimates how much petrol a journey will use and what that fuel will cost.

To calculate petrol cost:

1. Divide the distance by the vehicle's MPG.

2. Multiply the result by 4.546 to convert UK gallons into litres.

3. Multiply the litres used by the petrol price per litre.

Example: Petrol Cost for a 100-Mile Journey

Suppose a petrol car achieves 40 MPG.

For 100 miles:

100 ÷ 40 = 2.5 UK gallons

2.5 × 4.546 = 11.365 litres

If the petrol price you enter is £1.50 per litre, the calculation would be:

11.365 × £1.50 = £17.05

So the journey would cost approximately £17.05 in petrol at that example price.

The £1.50 figure is only an illustration. Fuel prices change, so use the current price you actually expect to pay.

For a current UK fuel-price figure, use the latest GOV.UK weekly road fuel prices rather than relying on an old number in this article.

Petrol Cost Per Mile

The formula is:

Petrol cost per mile = (petrol price per litre × 4.546) ÷ MPG

For example, at £1.50 per litre and 40 MPG:

(£1.50 × 4.546) ÷ 40 = 17.0p per mile

At the same petrol price, a 50 MPG car would cost approximately 13.6p per mile.

The cost per mile changes when either the fuel price or the vehicle's MPG changes.

Diesel Cost Calculator

A diesel cost calculator works in the same way as a petrol calculation.

Use the vehicle's diesel MPG and the diesel price per litre.

Example: Diesel Cost for a 100-Mile Journey

Suppose a diesel car achieves 55 MPG.

For 100 miles:

100 ÷ 55 = 1.818 UK gallons

1.818 × 4.546 = 8.264 litres

If diesel costs £1.60 per litre in this example:

8.264 × £1.60 = £13.22

The estimated fuel cost is therefore approximately £13.22 for 100 miles at that example price.

This is not a current UK diesel price. Use the latest pump price for your own calculation.

Diesel Cost Per Mile

The formula is:

Diesel cost per mile = (diesel price per litre × 4.546) ÷ MPG

At £1.60 per litre and 55 MPG:

(£1.60 × 4.546) ÷ 55 = 13.2p per mile

A diesel car's actual cost per mile depends on its fuel economy and the diesel price.

Journey Fuel Cost Calculator

A journey fuel cost calculator can be used for a commute, day trip, motorway journey or longer road trip.

For petrol or diesel:

Journey fuel cost = (distance ÷ MPG) × 4.546 × fuel price per litre

Example: 50-Mile Journey Fuel Cost

The following examples use £1.50 per litre for petrol purely to demonstrate the calculation.

Petrol MPG	Approx. fuel used	Example cost for 50 miles
30 MPG	7.58 litres	£11.37
40 MPG	5.68 litres	£8.52
50 MPG	4.55 litres	£6.82

Example: 200-Mile Journey Fuel Cost

Using the same illustrative £1.50 per litre petrol price:

Petrol MPG	Approx. fuel used	Example cost for 200 miles
30 MPG	30.31 litres	£45.47
40 MPG	22.73 litres	£34.09
50 MPG	18.18 litres	£27.27

These figures demonstrate the calculation rather than representing current UK fuel costs.

For a current estimate, replace the example price with the latest price you will actually pay.

UK Fuel Prices Used for These Calculations

Petrol and diesel prices change over time and can differ between retailers and locations.

For a current UK calculation, use the latest GOV.UK weekly road fuel prices or the actual price shown by the fuel station where you plan to fill up.

The most accurate calculation for an individual journey uses:

• Your actual fuel price per litre

• Your vehicle's real-world MPG

• The actual journey distance

• Your normal driving conditions

A national average is useful for comparison, but it will not necessarily be the price you pay.

Fuel Cost Per Mile Calculator

Fuel cost per mile makes it easier to compare vehicles with different fuel economy.

For petrol and diesel:

Fuel cost per mile = (fuel price per litre × 4.546) ÷ MPG

To express the answer in pence, multiply the result in pounds by 100.

Petrol Cost Per Mile Example

Using £1.50 per litre as an illustration:

MPG	Approx. petrol cost per mile
30 MPG	22.7p
40 MPG	17.0p
50 MPG	13.6p
60 MPG	11.4p

These figures change when the petrol price changes.

Diesel Cost Per Mile Example

Using £1.60 per litre as an illustration:

MPG	Approx. diesel cost per mile
40 MPG	18.2p
50 MPG	14.5p
55 MPG	13.2p
60 MPG	12.1p

Again, these are examples rather than current diesel prices.

Electric Cost Per Mile Example

Electric cars use electricity rather than litres of petrol or diesel.

The basic calculation is:

Electric cost per mile = electricity price per kWh ÷ miles per kWh

For example, if an electric car uses 3.5 miles per kWh and the electricity used for charging costs 30p per kWh:

30p ÷ 3.5 = 8.6p per mile

This is the energy cost based on the stated electricity price. It does not include other vehicle costs or any separate public-charging fees.

For home charging, use the electricity tariff that applies to the electricity used for charging.

For public charging, use the actual tariff charged by the charging network.

Also check: Super Unleaded vs Unleaded Petrol

Fuel Cost for Common UK Journey Distances

There is no fixed fuel cost for a particular distance because different cars use different amounts of fuel and fuel prices change.

As an illustration, a petrol car returning 40 MPG would use approximately:

Distance	Approx. petrol used
25 miles	2.84 litres
50 miles	5.68 litres
100 miles	11.37 litres
200 miles	22.73 litres
500 miles	56.83 litres

To calculate the cost, multiply the litres used by the current petrol price per litre.

For example:

100 miles ÷ 40 MPG × 4.546 = approximately 11.37 litres

At £1.50 per litre:

11.37 × £1.50 = approximately £17.05

How Much Fuel Will I Use?

To estimate petrol or diesel consumption:

Fuel used in litres = (Distance ÷ MPG) × 4.546

For example, a car returning 40 MPG over 100 miles would use approximately 11.37 litres.

This can help estimate:

• Fuel needed for a journey

• Weekly commuting fuel

• Monthly fuel consumption

• Annual fuel use

• Running costs between different cars

Official fuel economy figures are useful when comparing vehicles, but your actual MPG can be different in everyday driving.

How Much Does Petrol Cost Per Mile in the UK?

There is no single petrol cost per mile for every UK driver.

It depends mainly on:

• Petrol price per litre

• Vehicle MPG

• Driving conditions

• Actual fuel consumption

For example, at £1.50 per litre:

• 30 MPG = approximately 22.7p per mile

• 40 MPG = approximately 17.0p per mile

• 50 MPG = approximately 13.6p per mile

• 60 MPG = approximately 11.4p per mile

Use the current petrol price and your own vehicle's MPG for a more accurate result.

How Much Does Diesel Cost Per Mile in the UK?

Diesel cost per mile depends on the price of diesel and your vehicle's fuel economy.

For example, at £1.60 per litre, a 55 MPG diesel car would cost approximately 13.2p per mile in diesel.

A 40 MPG diesel car at the same price would cost approximately 18.2p per mile.

This is why comparing cost per mile can be more useful than simply comparing petrol or diesel prices.

Average Fuel Cost Per Mile UK

There is no single average fuel cost per mile that applies to all UK cars.

A small petrol car, large SUV and diesel estate can have very different MPG figures. The same vehicle can also return different MPG in urban traffic and motorway driving.

For an individual estimate, use:

(fuel price per litre × 4.546) ÷ MPG

If you are comparing cars, use the same fuel price and annual mileage for each vehicle. This gives you a consistent comparison.

How Much Is a Gallon of Petrol and Diesel in the UK?

A UK imperial gallon contains 4.54609 litres.

To calculate the equivalent price of a UK gallon:

Price per UK gallon = price per litre × 4.54609

For example, if petrol costs £1.50 per litre:

£1.50 × 4.54609 = £6.82 per UK gallon

If diesel costs £1.60 per litre:

£1.60 × 4.54609 = £7.27 per UK gallon

These are mathematical examples, not current UK pump prices.

A UK gallon should not be confused with a US gallon, which contains approximately 3.785 litres.

Petrol vs Diesel vs Electric Running Costs

Fuel or electricity is only one part of the cost of running a car.

When comparing vehicles, consider:

• Fuel or electricity

• Insurance

• Servicing and maintenance

• Vehicle tax

• Annual mileage

• Charging costs for an EV

• Purchase or lease payments

• Depreciation where relevant

An electric car's energy cost per mile can be lower than the fuel cost of some petrol or diesel cars, particularly when charging at home on a suitable electricity tariff. However, the result depends on the vehicle's efficiency, electricity price and where the car is charged.

Public charging can have a different price from home charging, so it should be calculated separately.

Also check: How Much Does It Cost to Charge a Tesla in the UK

Fuel Costs and Your Total Car Running Costs

Fuel is only one part of what it costs to run a car. If you are comparing vehicles, looking at fuel cost per mile gives you a useful starting point, but your overall monthly motoring cost can be quite different once other expenses are included.

For example, two cars could have similar fuel costs but different insurance, servicing and vehicle costs. Likewise, a more economical car can reduce fuel spending if you cover a high annual mileage.

It can therefore be useful to estimate:

• Fuel or electricity cost per mile

• Expected annual mileage

• Annual fuel or charging cost

• Insurance

• Servicing and maintenance

• Vehicle tax where applicable

• Monthly vehicle cost

How Annual Mileage Changes Fuel Costs

A small difference in cost per mile can become more noticeable over a year.

For example, if one car costs 17p per mile in petrol and another costs 13p per mile:

12,000 miles × 17p = £2,040

12,000 miles × 13p = £1,560

The difference is £480 a year in fuel at those example figures.

This is why fuel economy is worth considering alongside the monthly cost of the car, particularly if you drive several hundred miles each month.

Choosing a Car Based on Running Costs

Once you know your expected annual fuel or charging cost, you can compare it with the other costs of running the car.

If your current car is expensive to run, changing to a more efficient petrol, diesel or electric model may reduce your ongoing costs. Consider how much you drive, where you drive and how you will use the car rather than looking at fuel economy alone.

For some drivers, replacing an older car with a newer, more efficient model can also mean more predictable maintenance and running costs.

If buying a car outright is not the preferred option, car leasing is another way to access a newer vehicle with a fixed monthly vehicle payment, although fuel, insurance and other running costs are normally separate.

This means the fuel cost calculation can be used alongside the monthly lease cost to estimate a more realistic motoring budget before choosing a vehicle.

Fuel Cost Per Mile and HMRC Mileage Rates

A fuel cost calculation is not the same as an HMRC mileage rate.

HMRC mileage rates are used for specific business mileage and expense purposes. The amount you actually spend on fuel is calculated separately.

If you want to know how much your personal car costs to drive 100 miles, use your actual fuel price and vehicle MPG.

If you are claiming business mileage, check the current HMRC guidance and applicable mileage rates rather than using the result from this calculator as an expense rate.

Also check below links:

• No Deposit Car Leasing – spread the cost without upfront payments

• Business Car Lease Deals – drive the affordable car with lower running costs

• Used Electric Car Leasing – affordable way to go electric