EV Charging Time Calculator: 20 to 80% and Cost
How long will my EV take to charge? Enter battery size, start and target charge, charger power and efficiency to get the charging time, the energy added and the cost at your price per kWh. This page is about time and cost at the plug. For how many kilometres or miles that energy buys, use the EV range calculator.
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Formula
- Energy added:
kWh_added = capacity × (target % − start %) ÷ 100 - Energy from the charger:
kWh_grid = kWh_added ÷ efficiency - Time:
hours = kWh_added ÷ (charger kW × efficiency) - Taper (assumption, DC fast charging only, chargers of 22 kW or more): the part of the charge above 80% runs at 50% of the power, so that portion takes twice as long. Slower AC charging runs at a constant rate.
- Cost:
kWh_grid × price per kWh
Worked example
60 kWh battery, 20% to 80%, 50 kW charger, 90% efficiency, price 0.30. Energy added = 60 × 0.6 = 36 kWh. From the charger = 36 ÷ 0.9 = 40 kWh. Time = 36 ÷ (50 × 0.9) = 0.8 hours (48 min). Cost = 40 × 0.30 = 12.00.
For 20% to 100% the last 20% adds 12 ÷ 22.5 = 0.533 h, for 1.33 hours and 16.00.
Use this when
You are planning a stop on a trip, comparing a home charger with a public one, or estimating what an overnight charge costs. Home chargers of roughly 7 to 11 kW and public DC chargers of roughly 50 to 150 kW are typical.
EV charging time vs EV range
This page converts a charger and a battery gap into minutes and money. The EV range calculator converts the energy in the battery into distance.
Assumptions
The charger delivers constant power up to 80%, then half power when it is 22 kW or more. Below 22 kW (home AC charging) the rate stays constant. Real curves depend on the car, temperature and charger, so treat the result as an estimate.
Common mistakes
- Dividing by the charger rating alone and ignoring efficiency losses.
- Expecting the last 20 percent to charge as fast as the first 80.
- Forgetting that the car's onboard charger can be slower than the wall box.
Frequently asked questions
How long does it take to charge an EV from 20 to 80%?
A 60 kWh battery needs 36 kWh for 20 to 80%. On a 50 kW charger at 90% efficiency it receives 45 kW, so the charge takes 36 ÷ 45 = 0.8 hours, or 48 minutes.
Why does charging slow down above 80%?
Cars reduce charging power near full to protect the battery. This calculator assumes, for fast chargers of 22 kW or more, that the part above 80% runs at half power; slower AC chargers are treated as constant rate. Going from 20 to 100% in the example takes 1.33 hours instead of the 1.07 hours a constant rate would give.
What does charging efficiency mean?
Some energy is lost as heat in the charger and car. At 90% efficiency, 36 kWh added to the battery means 40 kWh drawn from the charger, and that is what you pay for.
How is the charging cost calculated?
Cost is the energy drawn from the charger times your price per kWh. 40 kWh at 0.30 per kWh costs 12.00. Public fast chargers may add session or idle fees that are not included.
How long does it take to charge an EV on a home 11 kW charger?
Charging a 60 kWh battery from 10 to 100 percent adds 54 kWh. At 90 percent efficiency an 11 kW charger delivers 9.9 kW, so it takes 5.45 hours (about 5 h 27 min) and draws 60 kWh from the grid.
How long does a 150 kW fast charger take from 10 to 80%?
For a 77 kWh battery, 10 to 80 percent adds 53.9 kWh. At 90 percent efficiency the charger delivers 135 kW, so it takes about 0.4 hours, or 24 minutes. Real cars often slow down, so treat this as a best case.
How long does it take to charge 40 kWh on a 7 kW charger?
A 40 kWh battery from 20 to 100 percent adds 32 kWh. A 7 kW charger at 90 percent efficiency delivers 6.3 kW, so the charge takes 5.08 hours (about 5 h 5 min) and costs 10.67 at 0.30 per kWh.