EV vs Gas Calculator
What an electric car costs to run against a petrol or diesel one, per km or mile and per year, and how many years the saving takes to pay back a higher purchase price.
Result…
How it's calculated
Electric cost per km = kWh per km ÷ charging efficiency × electricity price Fuel cost per km = litres per km × price per litre Yearly cost = cost per km × km a year + maintenance Saving = petrol or diesel yearly cost − electric yearly cost · Payback = extra price ÷ yearly saving
Both cars are put on the same footing: energy per kilometre times its price. The electric car's efficiency can be entered as kWh per 100 km or 100 miles, or as km or miles per kWh, and is turned into kWh per km (1 mile = 1.609344 km exactly). Charging loses some energy as heat, so the grid supplies more than the battery receives; the charging efficiency accounts for that. Fuel economy works the same way, in L/100 km, km/L or US or UK mpg (1 US gallon = 3.785411784 L, 1 UK gallon = 4.54609 L). The yearly saving is the difference in energy plus maintenance, and the payback is the extra purchase price divided by that saving, without interest or price changes.
Your numbers, step by step
About the EV vs Gas calculator
This EV vs gas calculator compares what an electric car and a petrol or diesel car cost to run, per kilometre or mile and per year, and shows how many years the yearly saving takes to pay back a higher purchase price. Enter how far you drive, the electric car's efficiency in kWh per 100 km or 100 miles or in km or miles per kWh, your electricity price, the other car's fuel economy in L/100 km, km/L or US or UK mpg, and the fuel price per litre or gallon. Add what you expect to spend on maintenance for each car. It suits anyone weighing up a switch, a fleet manager comparing models, or a driver checking whether home charging pays. Every step of the working is shown with your own numbers, and nothing is assumed about prices in your country.
How to use it
- Enter the “Distance driven a year” and choose kilometres or miles.
- Enter the “Electric car efficiency”, pick its “Efficiency unit”, and set a “Charging efficiency” (100 if your figure was measured at the wall).
- Enter the “Electricity price per kWh” you pay, averaged over home and public charging if you use both.
- Enter the “Petrol or diesel fuel economy” with its unit, and the “Fuel price” per litre, US gallon or UK gallon.
- Add each car's maintenance a year and the “Extra price of the electric car” to see the payback.
Worked example
A driver covers 12,000 km a year. The electric car uses 16 kWh/100 km at 90% charging efficiency, so it takes 2,133 kWh from the grid; at 0.28 per kWh that is 597.33, plus 250 maintenance = 847.33 a year, or 0.0498 per km in energy. The petrol car does 6.5 L/100 km: 780 L at 1.70 = 1,326, plus 550 maintenance = 1,876 a year, or 0.1105 per km. The saving is 1,876 − 847.33 = 1,028.67 a year, so an extra purchase price of 6,000 pays back in 6,000 ÷ 1,028.67 = 5.8 years.
Updated
Questions people ask
How do I compare the running cost of an electric car and a petrol car?
Work out the energy each uses per kilometre or mile and multiply by its price: kWh times the electricity price for the electric car, litres or gallons times the fuel price for the other. Multiply by your yearly distance and add maintenance to compare whole years.
What is the formula for EV payback time?
Payback in years = extra purchase price ÷ yearly running-cost saving. It ignores interest, resale value and future price changes, so treat it as a rough guide rather than an exact date.
Why include charging efficiency?
Some energy is lost as heat while charging, so the meter records more kWh than the battery receives. Leaving it out makes the electric car look slightly cheaper than it is. Use 100% if your efficiency figure already comes from the wall meter.
Does a higher electricity price always make the electric car more expensive to run?
Not always. It depends on how efficient each car is and on the fuel price. If the electric car costs more per kilometre or mile, the calculator says the extra price is never paid back at those figures.
What does the EV vs petrol comparison leave out?
Insurance, road tax, depreciation, finance, charger installation and grants are not included, and real efficiency changes with speed, weather and heating. For a buying decision, a dealer's full cost of ownership or an independent financial adviser can fill those gaps. The fuel cost calculator prices a single trip, and the EV charging calculator shows a single charge.