Will my EV be ready by morning? Generic tools only answer how long charging takes. The overnight decision is different: if you plug in at night and leave in the morning, on a tariff that is cheap for only part of the night, how much charge do you actually get, how much of it is cheap, and what is the latest you can start and still hit your target? This page answers that, including an off-peak window that crosses midnight. It runs entirely in your browser and saves or sends nothing.
Energy needed = battery size × (target % − current %). Effective charging power = charger power × efficiency. Charge duration = energy needed ÷ effective power. Departure is taken as the next occurrence of that clock time after plug-in, so 22:00 to 07:00 is 9 hours. If charging would finish after departure, the charge delivered by departure is what the page reports, not the target. The cheap/peak split is the overlap between the actual charging interval (plug-in to finish, or to departure if earlier) and the off-peak window, repeated across midnight as needed — so a window like 23:00–06:00 works too. Latest start = departure − charge duration.
With the defaults above: 60 kWh battery, 20% to 80% = 36.0 kWh needed. Effective power = 7 × 0.90 = 6.30 kW, so duration = 36 ÷ 6.30 = 5.71 hours. Starting at plug-in (22:00), charging finishes at 03:43, before the 07:00 departure, so the target 80% is reached. Latest start = 07:00 − 5.71 hours = 01:17. Charging 22:00–03:43 overlaps the cheap 00:00–05:00 window for 3.71 hours = 23.4 kWh cheap, and 12.6 kWh at peak price (22:00–00:00). At the entered prices that is 3.51 cheap + 4.41 peak = 7.92 in total.
Are the prices a tariff recommendation? No. Prices are whatever you enter, in your own currency, and tariffs, taxes and standing charges are not included — check your own tariff for the real cheap window and rates. Why is efficiency editable? Real charging loses energy to heat and to the car's own systems, and cold weather and a nearly full battery slow charging further; this page uses one flat efficiency for the whole charge, so treat the finish time as an estimate, not a guarantee. What if departure is too soon? The page shows the percentage actually reached by departure and the energy delivered, so you can see the shortfall instead of a false target. What if the off-peak window crosses midnight? Enter it as-is (for example 23:00 to 06:00); the overlap calculation handles it. Is this a charger or tariff recommendation? No. It only plans one night's charging from numbers you enter; you choose the charger and tariff yourself.
This is a free, single-purpose calculator. All calculation happens in your browser. No account, no upload, no tracking by this page beyond any ads Google may serve after approval.