Fuel cost calculator

Fuel cost calculator

Use the fuel cost calculator below to compare the costs of two cars. Select vehicles using the drop-down lists, then enter mileage, frequency and MPG criteria and your results will appear.

Based on your selections, the results will show cost per mile and weekly, monthly and annual fuel costs for both vehicles. The fuel cost calculator results are based on the current UK average petrol, diesel and electricity prices; these are editable if these do not reflect the prices you are paying in your area, or you wish to see the impact of a change in fuel prices.

1 Select cars to compare
Select car 1
- cc (0 litre) -
Used car
CO2: g/km Official MPG (Comb): MPG Real MPG (Comb): N/A MPG
Select car 2
- cc (0 litre) -
Used car
CO2: g/km Official MPG (Comb): MPG Real MPG (Comb): N/A MPG
2 Enter mileage and frequency
3 Change fuel cost assumptions
  • Fuel cost results will be based on the following average petrol, diesel and electricity prices. Edit the prices below if you wish to see calculations based on different prices.

Ready to calculate?

Using the fuel cost calculator

After having made your vehicle selection, there is an option to enter the mileage, frequency and MPG type. The mileage and frequency should reflect the period you typically use to monitor the fuel useage - a typical driver will travel 10,000 miles in a year.

For MPG type, the calculator defaults to Real MPG which is more representative of real-life driving conditions as compared to the Official MPG figure. It is widely acknowledged that the official figures overstate the achievable MPG and thus will also show a lower fuel cost per period.

The fuel price assumptions for petrol, diesel and electricity are based on a weekly average UK price. To change these figures to a figure more representative of your local area, or to see the impact of a change in the fuel prices, the drop-downs provided can be used to alter the prices. These will be reflected in the fuel cost calculator results.

How we calculate fuel costs

Fuel cost is calculated by multiplying a vehicle's fuel economy by fuel price and the distance driven. The calculator, which can be used for all vehicle types, provides two results – one based on official fuel economy data and the other representing real-world driving.

For light-duty vehicles that are powered by petrol, diesel or electricity, official performance data is sourced from the UK Vehicle Certification Agency (VCA) or manufacturers' websites. Real-world performance factors are ether estimated using established data sources (such as the ICCT) or modelled using available UK real road test data.

The calculation for vehicles powered solely by petrol, diesel or electricity is relatively straightforward as the official test data is widely published in the public domain, and real-world correction factors are well-known given the availability of large data sets generated by vehicles driven on real roads.

The data sourcing and calculation for plug-in hybrid electric vehicles is more complex, as they can be simultaneously powered by electricity and petrol or diesel. For the real-world estimate of fuel costs for PHEVs, the calculation assumes that the vehicle is driven for half the distance in EV-mode and half using a conventional fuel.

For more details of the methodology used to calculate fuel costs, download the PDF document: NGC Fuel Cost Calculator Methodology

Fuel cost calculator - calculate fuel consumption for cars
Chris Lilly

Author:Chris Lilly
Date Updated:10th Nov 2022

Latest news