EV charging cost calculator
Work out the approximate electricity cost of charging an electric car from one battery percentage to another. Include charging losses and your expected driving efficiency to estimate cost per mile.
Your charge
How the EV charging cost is calculated
Grid energy = battery energy ÷ (1 − charging-loss fraction).
Cost = grid energy × electricity price.
Estimated miles = battery energy × miles per kWh.
Charging is not perfectly efficient. Energy is lost in the charger, battery conditioning, conversion electronics and other systems, so your meter can record more energy than the battery actually stores. The default 10% is a planning assumption, not a universal figure.
For a home tariff, use the actual pence-per-kWh rate that applies while the car charges. For public charging, enter the operator’s displayed price. Real cost can also include session fees, parking charges or subscriptions that this calculator does not add automatically.
Example
A 77kWh usable battery charged from 20% to 80% stores 46.2kWh. With 10% losses, the grid supplies about 51.3kWh. At 25p/kWh that is about £12.83. At 3.5 miles/kWh, the energy added represents roughly 162 miles in idealised driving.
Which electricity price should you enter?
For home charging, use the unit rate that actually applies during the hours your car charges. If you have a time-of-use tariff, an overnight EV rate can be very different from the daytime price. For public charging, use the operator’s pence-per-kWh rate shown in its app or on the charger. Some networks also have membership pricing, connection fees or parking charges, so the calculated electricity cost may not equal the final receipt.
Why cost per mile can change
The miles-per-kWh figure is just as important as the electricity price. Cold weather, motorway speeds, heating, tyre pressure, payload and driving style can all reduce efficiency. For a conservative trip budget, use the efficiency you actually see in similar conditions rather than the car’s best-case figure.
How to use the EV charging cost calculator
Enter the vehicle’s usable battery capacity, starting and target state of charge, your electricity price and an allowance for charging losses. The calculator estimates the energy added to the battery and the larger amount that may need to be drawn from the grid.
Worked example
Charging a 60 kWh battery from 20% to 80% adds 36 kWh to the battery. With 10% charging losses, the grid energy is about 40 kWh; at 25p/kWh that works out at roughly £10.
EV charging cost FAQs
Why is grid energy higher than battery energy?
Some energy is lost in the charger, vehicle electronics, cabling and battery as heat, so the meter can record more energy than the battery actually stores.
Should I use my tariff’s peak or off-peak price?
Use the price that applies during the charging session. If charging spans different tariff periods, calculate them separately for a more realistic total.
Does the result include public charging session fees?
No. Add any connection, parking, idle or membership charges separately unless they are already included in the price you entered.