EV vs petrol running-cost comparison
Compare the electricity and petrol cost of covering the same distance using your entered efficiency and price figures. Use a trip distance for a journey comparison or annual mileage for an energy-cost projection; this does not compare purchase price or total ownership cost.
Result
EV cost
Petrol cost
EV saving vs petrol
How to use this tool
- Choose a distance that represents the comparison you care about, such as a regular trip or your annual mileage.
- Enter the EV's measured miles per kWh and the electricity unit price you pay.
- Enter the petrol car's real-world mpg and the pump price per litre you pay.
- Read both costs and the difference for the same distance.
Assumptions
- The prefilled efficiency and price values are illustrative inputs, not current market averages. Replace them with your own vehicle data and current tariff or pump prices.
- Uses one electricity price for the whole distance. For mixed home/public charging, enter a kWh-weighted average price; practical guidance below shows how to calculate it.
- Petrol mpg uses a UK imperial gallon (4.54609 litres), not a US gallon.
Sources & reference data
Technical details: what the fields mean
- Distance
distanceMiles - The same distance for both vehicles, such as one trip or your annual mileage for a yearly fuel-and-energy comparison.
- EV efficiency
evEfficiencyMiPerKwh - EV miles travelled per kWh.
- Electricity price
evPricePerKwh - Electricity price per kWh.
- Petrol fuel economy
petrolMpg - Petrol car's miles per UK gallon.
- Petrol price
petrolPricePerLitre - Petrol price per litre.
Methodology
EV cost = (distance ÷ efficiency) × price per kWh. Petrol cost = (distance ÷ mpg) × 4.54609 × price per litre. Saving = petrol cost − EV cost.
Worked example
Illustrative 10,000-mile scenario (the rates are examples, not current or typical market prices)
Inputs: Distance: 10000 miles, EV efficiency: 3.5 mi/kWh, Electricity price: £0.3/kWh, Petrol fuel economy: 45 mpg, Petrol price: £1.45/L
Result: EV: (10,000 ÷ 3.5) × £0.30 = £857.14. Petrol: (10,000 ÷ 45) × 4.54609 × £1.45 = £1,464.85. Difference: £607.71. All prices and efficiencies here are illustrative.
Practical guidance
- If you charge at home and publicly, calculate one kWh-weighted tariff rather than averaging the number of charging sessions. For example, an illustrative mix of 80% at 10p/kWh and 20% at 60p/kWh gives 20p/kWh.
- Run a second comparison with a different distance or tariff to see how sensitive the difference is to your actual usage.
Common mistakes
- Entering a total charge-session cost instead of a price per kWh; divide the session cost by the kWh added to get a comparable rate.
FAQs
What does the EV saving output mean?
It is petrol running cost minus EV energy cost for the same distance. A positive result means the EV energy cost is lower; a negative result means the petrol cost is lower.
Last reviewed: 2026-10-11
This compares energy/fuel for one selected distance; it is not an emissions estimate, vehicle recommendation or total ownership-cost model.
This tool provides an indicative estimate, based on the assumptions stated above.
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