EV Charging Cost Calculator
Work out exactly what it costs to charge your EV from any percentage to any other.
What a charge actually costs
The cost of charging an EV at home is the energy you draw from the wall multiplied by the price your utility charges per kilowatt-hour. The battery doesn't accept 100% of what comes from the wall — typically 5–15% is lost as heat in the on-board charger and the battery management system.
Worked example
A 75 kWh battery charging from 20% to 80% adds 45 kWh to the pack. With a 90% efficient charger, the wall delivers about 50 kWh. At $0.15 per kWh, the charge costs $7.50.
Where you charge matters
- Home overnight: usually the cheapest, especially on time-of-use plans (off-peak rates as low as $0.05–0.10 per kWh in many areas).
- Public Level 2: often $0.20–0.40 per kWh, sometimes free at hotels or stores.
- DC fast charging: the most expensive — commonly $0.40–0.60 per kWh, paid for the speed.
Real-world home efficiency lands between 85% and 92%. It drops slightly in extreme cold, because energy goes into warming the battery before it can take the full charge.
Frequently asked
How is the charging cost calculated?
Cost = battery capacity × percentage added, divided by charging efficiency, multiplied by your electricity rate. A 75 kWh battery going from 20% to 80% adds 45 kWh to the pack; with a 90% efficient charger, the wall draws about 50 kWh; at $0.15/kWh that is $7.50.
Why does the calculator factor in charging efficiency?
Some of the energy from your wall does not reach the battery — it is lost as heat in the onboard charger and the battery management system. Typical home AC charging is 85–92% efficient, so 100 kWh from the wall delivers about 88 kWh to the pack. The calculator reflects this so the result matches what your utility bill actually shows.
What charging efficiency should I use?
For most home charging at moderate temperatures, 88–92% is realistic. Drop to 80–85% in extreme cold, when more energy goes into warming the battery before it can take the charge. DC fast charging is generally more efficient (92–96%) because the AC-to-DC conversion happens in the charger, not the car.
Can I use this for public Level 2 or DC fast charging?
Yes — just change the electricity rate to match the public charger's per-kWh price (typically $0.20–0.40 for Level 2, $0.40–0.60 for DC fast). For DC fast charging you can also bump efficiency up to 92–96% since the AC-to-DC conversion happens in the charger.
What is a typical electricity rate to use?
The US national average is around $0.15/kWh, but state rates range from $0.10 (Idaho, Washington) to $0.40+ (Hawaii, top California tiers). Many utilities offer time-of-use plans that drop overnight rates to $0.05–0.10/kWh — signing up is usually the single biggest free win in EV ownership.
Does the calculator save my numbers?
No. The math runs entirely in your browser; nothing you type is sent anywhere or stored after you close the page.