Fuel Cost Calculator UK (2025) – Petrol, Diesel & EV Costs

Working out the real cost of driving in the UK can be tricky. Fuel prices change weekly, diesel and petrol efficiency varies by car, and electric charging costs depend on where you charge. That’s why so many drivers search for a fuel cost calculator UK — to get a clear, up-to-date picture of running costs.

This guide shows you how to calculate fuel costs yourself, with September 2025 UK fuel and energy prices, plus worked-out examples for petrol, diesel, and electric cars.

How to Calculate Fuel Costs in the UK (Formula)

The calculation is straightforward:

Fuel Cost (£) = Distance ÷ MPG × Fuel Price per Litre

• Distance: miles you plan to drive

• MPG: your car’s fuel efficiency

• Fuel Price per Litre: current UK average

For electric cars:
Cost (£) = Distance × Energy Consumption (kWh per mile) × Electricity Price per kWh

Petrol Cost Calculator UK (2025 Guide)

Petrol remains the UK’s most common fuel type.

Average petrol price (Sept 2025): £1.35/L

Example: 100 miles in a 40 MPG petrol car:

• 100 miles ÷ 40 MPG = 2.5 gallons × 4.546 = 11.37 litres

• 11.37 litres × £1.35 = ~£15.35

• Cost per mile = ~15p

This makes a petrol cost calculator useful for drivers comparing journey expenses.

Diesel Cost Calculator UK (2025 Guide)

Diesel cars usually offer better fuel economy than petrol, but the higher pump price reduces savings.

Average diesel price (Sept 2025): £1.42/L

Example: 100 miles in a 45 MPG diesel car:

• 100 miles ÷ 45 MPG = 2.22 gallons × 4.546 = 10.10 litres

• 10.10 litres × £1.42 = ~£14.34

• Cost per mile = ~14p

For long-distance drivers, diesel can still be competitive.

Electric Car Cost Calculator UK (2025 Guide)

Electric vehicles (EVs) are often the cheapest per mile, especially when charged at home.

Average home charging price (Sept 2025): 27p/kWh

Example: 100 miles in a car using 250 Wh/mile (0.25 kWh per mile):

• Total energy = 0.25 × 100 = 25 kWh

• 25 kWh × 27p = ~£6.75

• Cost per mile = ~7p

Public rapid chargers can be pricier, but home charging makes EVs the most affordable choice.

Average UK Fuel & Energy Prices (September 2025)

Fuel Cost per Mile UK: Petrol, Diesel & Electric Compared

EVs are around 50% cheaper per mile than petrol or diesel in 2025.

Journey Cost Examples

• Commute (20 miles round trip, 5 days a week):

  • Petrol: ~£15.35/week

  • Diesel: ~£14.34/week

  • Electric: ~£6.75/week

• Long trip (300 miles motorway):

  • Petrol: ~£46

  • Diesel: ~£43

  • Electric: ~£20

Why a Fuel Cost Calculator Matters

• Helps budget for daily commutes and road trips

• Compares running costs of petrol, diesel, and electric

• Useful for deciding between car leasing options

Check Options to Save on Fuel

Looking to explore more about reducing your motoring costs? Check out:

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

• Electric Car Lease Deals – drive the latest EVs with lower running costs

• Used Electric Car Leasing – affordable way to go electric