EV Charging Cost Calculator
Works out what a charge costs, counting the energy you are billed for rather than the energy that reaches the battery. The two differ by around 10% on home charging, and only the first appears on your bill.
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The formula
cost = (battery × charge added ÷ efficiency) × price per kWh
The efficiency term is what most charging calculators leave out. Charging is not lossless: at 90% you are billed for about 11% more energy than ends up in the battery.
What to watch out for
Four things that move this number more than people expect:
- Charging losses. AC home charging is roughly 85–90% efficient; DC rapid is a little better at the charger but adds battery heating. Either way you pay for kWh that never gets stored.
- The tariff matters more than the car. An off-peak EV tariff can be a third of the standard day rate. The same charge can cost three times as much depending only on when you plug in.
- Public rapid charging is a different product. It commonly costs four to six times the off-peak home rate, which is why home charging is most of the EV cost argument.
- 20–80% is the normal working range. Charging past 80% is slow on a rapid charger and harder on the battery, so most real charges are partial.
Frequently Asked Questions
How much does it cost to charge an electric car?
A 60 kWh battery from 20% to 80% stores 36 kWh, which is about 40 kWh billed once losses are counted. At $0.30/kWh that is roughly $12; on a $0.10 off-peak tariff, about $4.
Why do I pay for more energy than the battery holds?
Charging loses energy as heat in the onboard charger and the cells. At 90% efficiency, storing 36 kWh means drawing about 40 kWh from the wall — and the meter counts what leaves the wall.
Is it cheaper to charge at home or at a public charger?
Home, substantially. Public rapid charging typically runs four to six times an off-peak home rate. The gap is why home charging dominates the running-cost case for EVs.
Should I charge to 100%?
Not routinely. Most manufacturers suggest 80% for daily use and 100% only before a long trip. Above 80% charging also slows dramatically on a rapid charger, so the last 20% costs disproportionate time.