Doing this on a job? Save it to the job record in TradePlanr — with certificates, quoting and invoicing. Free to start.
Home charging at the tariff you enter. Public rapid charging costs several times more, and a dedicated off-peak EV tariff costs far less — run it again on those rates. Real efficiency varies with driving, load, speed and weather.
The TradePlanr app puts this calculator — plus gas & electrical certificates, quoting, invoicing and job sign-offs — on your phone, working even with no signal. Free to start — works in your browser, no download needed.
This calculator works out what it costs to charge an electric car at home. Enter the usable battery size, the car's efficiency in miles per kWh, your annual mileage and your electricity tariff, and it returns the cost per full charge, per mile and per year.
It is a handy tool to have when a customer weighing up an EV charger asks what charging will actually cost them. A clear answer — pence per mile and a yearly figure — helps them see the running-cost side of the decision, alongside the charger installation you are quoting.
The maths is straightforward: a full charge is the battery size times the unit rate, the per-mile cost is the unit rate divided by the car's efficiency, and the annual cost scales that up over the miles driven.
Cost per charge = battery kWh × tariff; Cost per mile = tariff ÷ efficiency; Annual = (miles ÷ efficiency) × tariff
A full charge costs the usable battery capacity multiplied by the electricity unit rate. The cost per mile is the unit rate divided by the car's efficiency in miles per kWh. The annual cost divides the yearly mileage by the efficiency to find the kWh used, then multiplies by the tariff.
Type the usable battery capacity in kWh — the figure the car actually charges to, from the spec sheet. A typical EV is 50–70 kWh.
Enter the car's efficiency in miles per kWh. Most EVs manage 3 to 4 miles per kWh depending on the car, driving and weather; 3.5 is a reasonable default.
Enter the yearly mileage and your electricity unit rate in pence per kWh. Use the customer's actual tariff, or an off-peak EV rate if they are on one.
The calculator shows the cost of a full charge, the cost per mile and the annual charging cost.
Home charging is the cheap case. These figures assume charging at home on the tariff you enter; public rapid chargers cost several times more per kWh, so a driver who charges out and about will spend far more than this suggests. Make clear the figure is for home charging.
An off-peak EV tariff changes everything. Dedicated overnight EV tariffs can be a fraction of the standard unit rate, which slashes the per-mile and annual cost. If the customer is considering one, run the calculation again on that rate to show the difference.
Real efficiency varies. Cold weather, motorway speeds and a heavy right foot all reduce miles per kWh, pushing the running cost up. Treat the output as a good average for planning, not a guaranteed figure, and use realistic efficiency for the car and the driving.
Home charging at the tariff you enter. Public rapid charging costs several times more, and a dedicated off-peak EV tariff costs far less — run it again on those rates. Real efficiency varies with driving, load, speed and weather.
A full charge costs the battery size multiplied by your electricity rate — a 60 kWh battery at 27p per kWh is about £16.20. Per mile that is roughly 8p at 3.5 miles per kWh. An off-peak EV tariff can cut this to a few pence a mile. Enter your figures above for a tailored answer.
Divide your electricity unit rate by the car's efficiency in miles per kWh. At 27p per kWh and 3.5 miles per kWh that is about 7.7p a mile. On a cheap overnight EV tariff of, say, 8p per kWh, the same car costs a little over 2p a mile.
Almost always at home. Home electricity, and especially a dedicated off-peak EV tariff, is far cheaper per kWh than public rapid charging, which carries a premium for the speed and infrastructure. This calculator assumes home charging; public charging will cost considerably more.
Yes. Cold weather reduces range and efficiency because the battery and cabin need heating, so you use more kWh per mile and the running cost rises. Motorway speeds have the same effect. Use a realistic miles-per-kWh figure for the conditions rather than the best-case number.
TradePlanr Agency builds custom-coded, SEO-optimised websites and runs Google Ads for UK trades — from £375, by the team behind TradePlanr.
Explore TradePlanr Agency