EV vs Petrol & Diesel Running Cost Calculator UK 2026
Switching to an electric car can save thousands of pounds a year on fuel — but the exact figure depends on how far you drive, what you pay for electricity, and how much charging you do at home. This calculator uses real UK pump prices and electricity tariff rates to show you the true running cost difference between an EV and a comparable petrol car, based on your own numbers. Adjust any figure to match your situation; results update instantly.
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How this calculator works
Petrol cost per mile is calculated by multiplying the petrol price (p/litre) by 4.546 litres per gallon, then dividing by your MPG. The EV cost uses a blended charging rate — a weighted average of your home and public rates based on the percentage of charging you do at each — divided by the car's efficiency in miles per kWh.
The result is the annual fuel cost for each option at your stated mileage. All figures are estimates for planning purposes. Real-world results vary with driving style, speed, season (battery efficiency drops in cold weather), and changes in energy prices.
Making the most of off-peak tariffs
The biggest lever you can pull is your home charging rate. Standard electricity costs around 24–25p/kWh, but EV-specific overnight tariffs can cut that to 8–9p/kWh. At 10,000 miles/year on Octopus Intelligent Go (8p/kWh) instead of the standard rate, the difference is around £350 extra annual saving — purely from the tariff switch.