Electric vs Petrol Running Cost Calculator
Compare EV and petrol cost per mile with verified 2026 UK Ofgem and fuel figures
Last updated: June 2026
Electric vs petrol: which is cheaper to run in 2026?
This electric vs petrol running cost calculator shows you exactly how much you would spend on fuel or electricity to cover your annual mileage — and how much you could save by switching to an EV. It works out the true cost per mile for each, then projects your spend over a year and over five years of ownership. Enter your annual mileage, the petrol pump price and your car's MPG, then pick how you would charge an electric car: a cheap home off-peak EV tariff (around 7p/kWh), the standard home rate (24.67p/kWh under the Ofgem price cap for April–June 2026), or expensive public rapid charging (around 75p/kWh).
It is built for UK drivers weighing up a switch to electric, company-car drivers comparing fuel against electricity reimbursement, and anyone who simply wants to know whether an EV actually saves money on the school run and commute. Because charging cost is the single biggest variable, the calculator lets you change every figure so the result reflects your car and tariff rather than a national average. All defaults use verified 2026 UK figures.
How it works
The maths behind the calculator is simple and transparent:
- Petrol cost per mile = (pump price in £ per litre × 4.546) ÷ MPG. The 4.546 converts an imperial gallon to litres, because MPG in the UK is measured in imperial gallons.
- Electric cost per mile = (electricity price in £ per kWh) ÷ miles per kWh.
- Annual cost = cost per mile × your annual mileage. The five-year figure simply multiplies that by five.
A typical efficient petrol car returns around 45 MPG; a typical EV manages about 3.5 miles per kWh in mixed UK driving. HMRC's Advisory Electricity Rate for company-car EVs is currently 7p per mile, which lines up closely with home off-peak charging in this tool.
Worked example
Suppose you drive 10,000 miles a year. Your petrol car does 45 MPG and petrol costs 145p per litre. You would charge an EV at the standard home rate of 24.67p/kWh, and it does 3.5 miles per kWh.
- Petrol: (1.45 × 4.546) ÷ 45 = 14.65p per mile → £1,464.82 a year
- Electric: (0.2467) ÷ 3.5 = 7.05p per mile → £704.86 a year
That is a saving of about £759.97 a year, or roughly £3,799.83 over five years — and the gap widens dramatically if you charge on a cheap overnight EV tariff (around 7p/kWh), where running costs fall to about 2p per mile (£200 a year at 10,000 miles).
Frequently asked questions
Is an electric car really cheaper to run than petrol?
For most drivers, yes — provided you can charge at home. On a home off-peak EV tariff (around 7p/kWh) an EV can cost about 2p per mile versus roughly 14–15p per mile for a 45 MPG petrol car. Even at the standard home rate of 24.67p/kWh an EV is usually still cheaper. The exception is relying solely on public rapid charging at around 75p/kWh, which can erase or reverse the saving.
What electricity price should I use?
Use the rate you actually pay to charge. The Ofgem price cap sets a standard variable electricity rate of 24.67p/kWh for 1 April to 30 June 2026 (including VAT). Many EV drivers use a dedicated off-peak tariff that drops to around 7p/kWh overnight, while public rapid chargers often cost around 75p/kWh.
Does this calculator include tax, insurance and depreciation?
No. It compares fuel and electricity running costs only, so you can see the energy saving clearly. Total cost of ownership also depends on the purchase price, depreciation, insurance, Vehicle Excise Duty (EVs began paying road tax from April 2025) and servicing, which vary widely by vehicle.
How do I convert MPG to cost per mile?
Multiply the pump price (in £ per litre) by 4.546 to get the cost of one imperial gallon, then divide by your MPG. For example, at 145p (£1.45) per litre and 45 MPG: (1.45 × 4.546) ÷ 45 = 14.65p per mile.
Sources: electricity unit rate from the Ofgem energy price cap (24.67p/kWh, 1 April–30 June 2026); petrol prices from the GOV.UK weekly road fuel prices; electric mileage rate cross-checked against the HMRC Advisory Electricity Rate (7p per mile).