EV Charging Time Calculator

Charging time depends on three things: battery capacity (in kWh), how much charge you need to add, and the charger's power output (in kW). The basic equation is straightforward: kWh needed divided by charger power equals hours, with a real-world adjustment for the charging curve. A 50 kWh battery filled from 20% to 80% needs 30 kWh; on a 7 kW home charger that takes about 5 hours, on a 50 kW rapid charger about 40 minutes.

The catch is that fast chargers slow down dramatically as the battery fills. Most EVs charge fastest between 10% and 60% state of charge, then taper sharply above 80%. Charging from 0 to 80% on a 150 kW ultra-rapid might take 25 minutes; the final 20% to 100% can take another 30 minutes alone. The calculator applies a sensible 80% efficiency factor to the headline charger power to reflect this real-world behaviour.

A standard UK three-pin socket delivers about 2.3 kW (limited by the 13A fuse), which means a 50 kWh battery from 20% to 80% takes around 13 hours. Workable for an overnight top-up but slow if you need to add more than 100 miles in a session. A dedicated 7 kW home wallbox is the standard upgrade and roughly halves the time, getting the same charge done in around 4 to 5 hours overnight.

22 kW chargers are not generally usable at home in the UK because most domestic supplies are single-phase and capped at 7.4 kW. Some properties have three-phase supplies that support faster home charging, but installation costs jump significantly. The OZEV grant helps cover wallbox installation if you rent or live in a flat. For the rest, a 7 kW unit is the sweet spot of cost vs speed for daily use.

On a long-distance trip, public charger speed matters more than overnight time. A 50 kW rapid charger (the most common UK roadside type) gives a typical mid-size EV around 100 miles of range in 30 to 45 minutes. A 150 kW ultra-rapid (Tesla V3 Supercharger, IONITY, GRIDSERVE high-power bays) can do the same in 15 to 20 minutes, but only if your car supports that peak rate; many older EVs cap at 50 to 100 kW regardless of the charger.

Cost varies widely. Home electricity at 28p/kWh is the cheap baseline. Public rapid charging routinely costs 70p to 85p/kWh during peak times, sometimes more. Charging a 60 kWh battery from 20% to 80% (36 kWh added) costs around £10 at home and £25 to £30 on a public rapid. Use the [road trip cost calculator](/road-trip-cost-calculator) to compare total trip costs against petrol and diesel.

Some scenarios make rapid charging genuinely uneconomical. Adding 5% to 10% on a public rapid (just to make a destination) costs disproportionately because of the per-session connection fee that some operators charge. Charging from 80% to 100% on a high-speed charger is also slow and expensive: the battery is already full enough for most journeys, so it is usually faster overall to unplug at 80% and continue.

If you have a wallbox at home, the dominant pattern is overnight top-ups using off-peak tariffs. Octopus Go and similar EV-specific tariffs offer rates as low as 7.5p/kWh between midnight and 5am, which makes a 50 kWh full charge cost around £3.75. That is the figure that makes EV total ownership genuinely cheaper than petrol; without home charging access, the total cost picture changes significantly.