Electric vs Petrol vs Diesel Cost Calculator UK

Which is cheaper to run?

Compare electricity, petrol and diesel costs for the same mileage.

How far do you drive?

That's 10,000 miles a year.

How do you usually charge?

These percentages need to add up to 100%.

Choose the closest match

Pick the closest option. We show the exact value used in the calculation under each field.

Electric

Battery size

Used for full-charge cost and range: 60 kWh

Efficiency

Used in calculation: 4 mi/kWh

Higher mi/kWh means the EV uses less electricity per mile. 4.0 mi/kWh is a neutral example; charging losses are added separately.

Petrol

Tank size

Used for full-tank cost and range: 50 litres

Engine size

HMRC mean used: 42.8 mpg

Choose the closest engine size. We then apply the matching HMRC mean MPG. If you know your own MPG, enter it instead.

Diesel

Tank size

Used for full-tank cost and range: 50 litres

Engine size

HMRC mean used: 49.6 mpg

Choose the closest engine size. We then apply the matching HMRC mean MPG. If you know your own MPG, enter it instead.

Change prices and assumptions

Petrol price (p/litre)Diesel price (p/litre)Energy lost while chargingDfT modelling uses an 11.8% charging-loss assumption for BEVs. We show this as 12% for readability.Example journey (miles)

About these figures. We compare all three options over the same mileage. Results include electricity or fuel only — not vehicle price, insurance, tax, servicing or depreciation. Battery and tank sizes are representative examples; they affect full charge/tank cost and estimated range, but not cost per mile when efficiency is unchanged.

Prices checked 7 September 2026. Petrol 161.61p/l and diesel 183.49p/l are the latest available UK DESNZ averages (week commencing 31 August 2026; the next release is due 8 September). Home charging uses the Ofgem Great Britain average price-cap unit rate of 26.11p/kWh for 1 July–30 September 2026; Northern Ireland tariffs differ and standing charges are excluded. Public <50kW uses Zapmap's August 2026 weighted PAYG average of 54p/kWh; Rapid/Ultra-rapid 50kW+ uses 77p/kWh, updated 4 September 2026. The EV-tariff option is an Octopus Intelligent Octopus Go example from 8p/kWh, not a UK-wide EV-tariff average. HMRC MPG bands are effective from 1 September 2026 and use manufacturers' data weighted by business-car sales. EV efficiency is a representative scenario rather than a claimed UK market average; charging losses use the DfT 11.8% modelling assumption.

Sources: DESNZ fuel prices · Ofgem price cap · Zapmap Price Index · Intelligent Octopus Go · HMRC advisory fuel rates methodology · DfT EV energy-consumption research.

How does this electric vs petrol vs diesel cost calculator work?

Enter how far you drive, how you usually charge, and the closest electric, petrol and diesel vehicle. The calculator compares all three over the same mileage and shows the estimated yearly cost, monthly cost and cost per mile.

You can enter mileage by week, month or year. The results are always scaled to a full year, then divided by 12 for the monthly figure. Open Change prices and assumptions to use your own petrol or diesel price, change charging losses, or try a different example journey.

What the results include

The figures cover electricity or fuel only. They leave out the price of the car, insurance, vehicle tax, servicing and depreciation. Battery size and tank size change the full-charge or full-tank cost and the estimated range. They do not change the cost per mile if efficiency stays the same.

Per mile — electricity or fuel cost for one mile at the prices and efficiency you chose.

Full charge or full tank — the cost to fill the battery or tank you selected.

Estimated range — how far that full charge or tank should take you.

Equivalents a year — how many times you would use that amount of electricity or fuel over your annual mileage.

Where the default prices come from

Petrol and diesel defaults use UK DESNZ weekly averages. Home charging uses the Ofgem Great Britain average price-cap unit rate. Public and rapid charging use Zapmap pay-as-you-go averages. The EV tariff option is an Octopus Intelligent Octopus Go example, not a UK-wide average. Northern Ireland electricity tariffs differ, and standing charges are not included.

Petrol and diesel efficiency bands use HMRC advisory fuel rate mean MPG figures. If you know your own MPG, choose I know my MPG and enter it. Electric efficiency is a representative example. Charging losses default to the DfT 11.8% modelling assumption, shown as 12% in the calculator. The sources and the date the prices were checked are listed under Change prices and assumptions.

These are estimates for comparison, not a quote for a particular car or energy tariff. Fuel and charging are only part of the cost of running a car. For how a vehicle loses value, use the car depreciation calculator. If you are comparing an electric car on finance, see electric car finance.

Electric vs Petrol vs Diesel Cost Calculator