EV Charging Time Calculator
Type your battery size, how full it is, how full you want it and the charger’s power. You get the charging time straight away, plus the car’s limit, range added and cost in Advanced.
The usable kWh in your car’s specs. Small cars often have 40–60 kWh, bigger ones 70–100 kWh.
2.3–3.7 kW: a wall plug or slow charger. 7.4–22 kW: home and workplace AC chargers. 50–350 kW: DC rapid chargers.
Rough figures: about 90% on AC, 95% on DC. Some energy turns to heat.
Your car’s limits
Also called the onboard charger. 7.4 or 11 kW is common. Leave blank for no limit.
The peak in your car’s specs; 50–250 kW is common.
A straight-line guess: the power falls evenly from the start % to this share at 100%. Real charging curves vary a lot between cars and with battery temperature.
Charger power from volts and amps
For 3-phase use the line-to-line voltage (often 400 V; 3 × 230 V gives almost the same answer).
Range added
From the trip screen. Many cars use about 14–20 kWh/100 km (3–4.5 mi/kWh); more in winter and on motorways.
Cost
Example prices only; they follow your currency until you type your own. Use your tariff or the charger app’s price.
Charge to 80% by a set time
Time on each charger size
How your charging time is worked out
Energy to add, the power the car takes, losses, then divide.
- 1
Energy to add
60 kWh × 60%(20% → 80%)= 36 kWh
- 2
Power the car takes
charger 7.4 kWcar limit 11 kW= 7.4 kW
- 3
After losses
7.4 kW × 90%= 6.66 kW
- 4
Charging time
36 ÷ 6.66= 5 h 24 min
Read more: the formula, a worked example, DC slow-down, volts × amps and cost
Charging time is the energy you need to add divided by how fast it goes in. The speed is the lower of what the charger gives and what your car accepts, less a little lost as heat. On DC rapid chargers most cars also slow down as the battery fills.
The formula
energy to add (kWh) = battery kWh × (target % − start %) ÷ 100
power used (kW) = the lower of charger kW and the car’s max kW
power into the battery = power used × efficiency
hours = energy to add ÷ power into the battery
Worked example
A car with a 60 kWh battery goes from 20% to 80% on a 7.4 kW AC home charger, with a rough 90% efficiency. The car takes up to 11 kW on AC, so the charger is the limit.
Energy to add: 60 × (80 − 20) ÷ 100 = 36 kWh. Power into the battery: 7.4 × 0.9 = 6.66 kW. Time: 36 ÷ 6.66 = 5.405 hours; 0.405 × 60 = 24.3 minutes, so about 5 h 24 min.
You pay for 36 ÷ 0.9 = 40 kWh. At an example home price of $0.17 a kWh that is 40 × 0.17 = $6.80; at a public $0.45 a kWh, 40 × 0.45 = $18.00. At 17 kWh/100 km the 36 kWh adds 36 ÷ 17 × 100 = 211.8 km (131.6 miles). Plugged in at 22:00, it is done at about 03:24, well before 07:00.
When the car is the limit
On a 22 kW charger the same car still takes only 11 kW: 11 × 0.9 = 9.9 kW, and 36 ÷ 9.9 = 3.64 hours (3 h 38 min). A 350 kW charger on a car with a 150 kW peak gives at most 150 kW.
DC slow-down (rough)
power at s% = peak × (1 − k × (s − start %))
k = (1 − power left at 100%) ÷ (100 − start %)
slow hours = (battery kWh ÷ 100 ÷ peak) × ln((1 − k × a) ÷ (1 − k × b)) ÷ k
Here a and b are how far past the start % you begin and end. Example: 60 kWh from 20% to 100% on a 150 kW charger, a car that takes 150 kW and 95% efficiency, so 142.5 kW goes in. From 20% to 80%: 36 ÷ 142.5 = 0.2526 h (15.2 min). From 80% to 100% with the power falling to 20% of peak: k = 0.8 ÷ 20 = 0.04, and (0.6 ÷ 142.5) × ln(1 ÷ 0.2) ÷ 0.04 = 0.004211 × 40.24 = 0.1694 h (10.2 min). Total about 25 minutes, against 20 minutes with no slow-down. This is a simple straight-line model; real cars each have their own curve, so treat it as a guide.
Charger power from volts and amps
1-phase kW = volts × amps ÷ 1,000
3-phase kW = 1.732 × volts (line to line) × amps ÷ 1,000
230 V × 32 A ÷ 1,000 = 7.36 kW. 1.732 × 400 V × 16 A ÷ 1,000 = 11.08 kW (11.09 kW with √3 in full). A US 240 V circuit at 40 A gives 9.6 kW.
Typical charger sizes
| Charger | Power | Type |
|---|---|---|
| Wall plug (10 A at 230 V) or US 120 V Level 1 | 1.4–2.3 kW | AC |
| 16 A one-phase | 3.7 kW | AC |
| 32 A one-phase home charger | 7.4 kW | AC |
| 16 A / 32 A three-phase | 11 / 22 kW | AC |
| Rapid charger | 50 kW | DC |
| Ultra-rapid chargers | 150–350 kW | DC |
These are estimates. Real charging time also depends on battery temperature (cold batteries charge slowly), the car’s own charging curve, sharing a charger with another car, and the supply. Efficiency and the slow-down figures are rough guides you can change; check your car’s specs.
Common questions
How long does an electric car take to charge?
Work out the energy you need to add, then divide by the power that reaches the battery. A 60 kWh battery from 20% to 80% needs 60 × 0.6 = 36 kWh. On a 7.4 kW home charger with about 90% efficiency, 7.4 × 0.9 = 6.66 kW goes in, so it takes 36 ÷ 6.66 = 5.4 hours, about 5 h 24 min.
Why does my car charge slower than the charger’s kW?
The car decides how much power it takes. Many cars accept only 7.4 or 11 kW on AC, so a 22 kW charger gives them no more than that. On DC rapid chargers the car also has a top rate, and it slows down as the battery fills. Use the lower of the charger’s and the car’s figure.
Why is charging from 80% to 100% so slow?
On DC rapid chargers, most cars cut the power as the battery gets full, to protect it. That is why rapid-charging times are often quoted from 10% or 20% to 80%. This calculator has a rough straight-line slow-down you can tune; real curves vary a lot between cars.
How many kW is my home charger?
Multiply volts by amps and divide by 1,000. A one-phase 230 V supply at 32 A gives 230 × 32 ÷ 1,000 = 7.36 kW (sold as 7.4 kW). A three-phase 400 V supply at 16 A gives 1.732 × 400 × 16 ÷ 1,000 = 11.1 kW. A US 240 V Level 2 charger at 40 A gives 9.6 kW.
How much does it cost to charge an electric car?
Divide the energy added by the charging efficiency to get the energy you pay for, then multiply by your price per kWh. 36 kWh at 90% efficiency is 40 kWh from the charger; at $0.17 a kWh that is $6.80. At a public charger at $0.45 a kWh it is $18.00, plus any session or per-minute fees.
Related calculators
Made by Zulu Calculator, part of AlphaZulu LLC. Formulas are shown in full and rule figures are checked against official sources; see how we build calculators.