Inputs
Enter your annual mileage, realistic EV miles per kWh, home or public charging price, petrol MPG, and pump price per litre.
Vehicle cost calculator
Electric car vs petrol cost calculator
Compare annual running energy costs for an electric car and a petrol car. Use your mileage, tariff, EV efficiency, MPG, and petrol price for a quick like-for-like estimate.
Method
EV cost is annual kWh multiplied by electricity price. Petrol cost converts MPG to litres using an imperial gallon of 4.54609 litres.
Result
The result compares energy and optional annual extras only. It does not include purchase price, insurance, tax, depreciation, servicing, charging losses, or finance.
Last reviewed: 16 June 2026Calculation type: running energy cost estimate
How to make the comparison useful
This calculator is designed for a narrow question: how much the driving energy costs might differ between an electric car and a petrol car over a year. It is not a full ownership calculator. That distinction matters because depreciation, finance, insurance, vehicle tax, servicing, tyres, and parking can outweigh energy savings for some drivers.
- Annual mileageUse the miles you actually expect to drive, not the advertised average. Energy savings scale directly with mileage.
- EV efficiencyUse a real-world miles-per-kWh figure from the car display, trip computer, or owners' data. Cold weather, motorway driving, and heavy loads can reduce efficiency.
- Charging priceUse the rate you will actually pay. Home charging, workplace charging, and rapid public charging can produce very different results.
- Petrol economyUse a real MPG figure if you have one. Official economy figures are useful for comparison, but can be optimistic for short journeys or urban traffic.
Worked example
At 8,000 miles per year and 3.5 miles per kWh, the EV uses about 2,286 kWh. At 24p per kWh, that is roughly £549 per year. A petrol car doing 45 mpg uses about 808 litres over the same mileage. At 145p per litre, that is roughly £1,172 per year, so the energy-only saving is about £623.
Why does the calculator use miles per kWh?
Miles per kWh is a direct way to estimate how much electricity the car needs. If your car reports kWh per 100 miles, divide 100 by that number to get miles per kWh.
Should I include road tax or servicing?
Only use the extras fields if you want a rough annual adjustment. The core comparison is energy cost, so keep insurance, depreciation, and finance separate unless you are building a wider ownership estimate.
Why might my real saving be lower?
Public rapid charging, winter driving, low EV efficiency, high motorway speeds, or a very efficient petrol car can reduce the gap. Use your own numbers for the most useful estimate.