EV charging time calculator for any socket, wallbox or rapid charger
This EV charging time calculator answers “how long will it take to charge my electric car?” from any starting percentage to any target. Enter the battery size and the charger, by kilowatts or by amps, volts and phases, and it shows the time, the power the car really draws and how much range you add.
It accounts for the two things most quick estimates miss: the car’s own on-board charger, which caps AC charging however big the wallbox, and the way DC rapid charging slows down as the battery fills. A table compares the same charge on a 3-pin plug, a 7 kW or 11 kW wallbox and 50–350 kW rapid chargers.
How to work out EV charging time
- Pick a Charger preset, or choose AC or DC rapid and enter your own figures.
- Enter the Usable battery capacity and the Charge from and Charge to percentages.
- For AC, check the Voltage per phase, Current and Supply phases, and the car’s On-board charger kW and phases. In the US you can enter the breaker size instead.
- For DC, enter the charger power and the car’s maximum DC power; adjust the slow-down point if you know your car’s curve.
- Optionally enter the car’s energy use to see the range added, then read the time, the chart and the comparison table.
EV Charging Time Calculator features
Amps, volts and phases
Power = phases × voltage × current, for 1-phase, 3-phase and US split-phase supplies.
On-board charger limit
AC charging is capped by the car’s charger, and a 1-phase charger uses only one phase of a 3-phase supply.
Breaker sizing
US circuits charge at 80% of the breaker rating, so a 40 A breaker gives 32 A.
DC slow-down model
Full power up to a chosen charge level, then a straight-line fall — editable and clearly labelled.
Range per hour
km or miles added from your car’s energy use.
The EV charging time formula
Energy into the battery = usable capacity × (charge to − charge from) ÷ 100. AC charging power = phases × voltage × current ÷ 1,000, but never more than the car’s on-board charger. Time = battery energy ÷ (power × (1 − charging loss)).
Worked example: a 60 kWh car charged from 20% to 80% takes in 36 kWh. A 230 V, 32 A single-phase wallbox supplies 7.36 kW; with a 7% loss that is 36 ÷ 0.93 ÷ 7.36 = 5.26 hours, about 5 h 16 min. On a UK 3-pin socket at 10 A (2.3 kW, about 15% loss) the same charge takes over 18 hours.
Why charging slows down near full
Lithium-ion cells accept less current as their voltage rises, so the car’s battery management lowers the power, usually from about 70–80% on rapid chargers. The US Department of Energy notes that charging power varies with the vehicle and the battery’s state of charge. That is why makers quote 10–80% times and why stopping at 80% on a journey is often quicker overall.
The calculator models this as full power up to the “Slows down above” level, then a straight-line fall to the “Power left at 100%” share. The defaults (80% and 20%) are an illustration, not measured data for any car; if you know your car’s curve, change them. Set the power left to 100% to switch the slow-down off.
Typical charger power
| Charger | Supply | Power |
|---|---|---|
| UK 3-pin socket | 230 V × 10 A | 2.3 kW |
| US Level 1 | 120 V × 12 A | 1.4 kW |
| Single-phase wallbox | 230 V × 32 A | 7.4 kW |
| US Level 2 | 240 V × 32–80 A | 7.7–19.2 kW |
| 3-phase wallbox | 3 × 230 V × 16 / 32 A | 11 / 22 kW |
| DC rapid | — | 50–350 kW |
EV Charging Time Calculator FAQ
How do I calculate EV charging time?
Divide the energy you add (battery kWh × change in %) by the charging power, then allow for 5–15% losses. The EV charging time calculator above also applies the on-board charger limit and the DC slow-down.
How long does it take to charge an EV at 32 amps?
At 230 V a 32 A single-phase charger gives 7.36 kW, so 36 kWh (20–80% of 60 kWh) takes about 5 h 16 min. At 240 V in the US, 32 A gives 7.68 kW.
Why does my car charge at 7 kW on an 11 kW or 22 kW charger?
The on-board charger sets the limit for AC charging. Many cars accept 7.4 kW on one phase, or 11 kW on three phases; a car with a single-phase charger draws from only one phase of a 3-phase wallbox.
What size breaker do I need for EV charging?
In the US, EV charging is a continuous load, so the National Electrical Code (Article 625.41) sizes the circuit at 125% of the charger current: a 32 A charger needs a 40 A breaker. Ask a qualified electrician.
How long does DC rapid charging take?
At a 150 kW charger a car that accepts 120 kW adds 36 kWh in about 19 minutes before it starts slowing down; going to 100% takes much longer.
Are the results exact?
No. Cold batteries, preconditioning, shared chargers and each car’s curve change real times. Treat the result as a planning estimate.