Electric Car Charging Cost Calculator
Calculate what an EV charging session could cost at home and on a public charger. Use usable battery capacity, the change in charge level, efficiency and any session fees.
How to use Electric Car Charging Cost Calculator
1. Choose the currency used for results. 2. Enter usable battery capacity and the start and target charge percentages. Choose electricity prices and add session fees or expected extras once. 3. Change a value to update the results, or select Calculate. Review the chart and notes with the total. 4. Use Copy results, Share results or Download result graphic to keep the answer. Shared links include your figures. 5. Reset restores the editable example inputs.
Why use this tool?
Charging from 20% to 80% is not the same as buying a full battery’s worth of electricity. The energy reaching the battery is only the change in charge level, while charging losses can make the electricity bought larger. Seeing the energy and the bill separately helps when comparing a home tariff with a public charger. Extra charges can matter, particularly for a small top-up. The yearly view repeats the same entered session pattern; it does not assume every charging session will have identical conditions.
How the calculation works
Energy added to the battery = usable battery capacity × (target percentage − starting percentage) ÷ 100. Electricity bought = battery energy added ÷ (charging efficiency ÷ 100). Session cost = electricity bought × price per kWh + entered session fee. Yearly cost repeats that session the entered number of times. Efficiency is editable. The model does not estimate battery conditioning, temperature effects, idle charges or time-based fees automatically. Include an expected monetary extra in the session fee when relevant.
Example
A usable 60 kWh battery charged from 20% to 80% stores 36 kWh. At 90% efficiency, 40 kWh is bought. Illustrative rates of £0.25/kWh at home and £0.60/kWh publicly give £10 and £24 respectively; adding a £1 public session fee makes that option £25.
Practical tip
Use usable capacity rather than a manufacturer’s gross capacity when the distinction is available. Check whether a public price also has parking, connection or idle fees.
Frequently asked questions
Why is electricity bought higher than energy added?
The difference represents losses under the charging-efficiency assumption. At 90% efficiency, divide battery energy by 0.9 rather than simply adding 10%.
Does this include an idle or time-based charge?
Only if you include its expected monetary amount in the extra-fee field. Charging duration and a time-based price are not automatically modelled.
Can the starting and target charge be the same?
Yes. That gives no battery energy increase. An entered session fee can still produce a cost, so set it to zero if no fee would actually be charged.