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EV Charging Time Calculator

Calculators · Added

Enter the battery size, where the charge is now and where you want it, and pick the charger. The estimate accounts for the two things that catch people out: on AC the car's own on-board charger is usually the limit rather than the wallbox, and on DC the power ramps down sharply past about 80 per cent, so the last stretch takes far longer than the arithmetic suggests.

kWh

The usable figure, not the gross one.

%
%

230 V x 32 A. The common home wallbox in the UK, Ireland and India.

Supply type
Charger power

7.4 kW

Set by the charger above. Choose Custom to enter your own.

kW

The hard ceiling on any AC charge. Commonly 3.3, 7.4, 11 or 22 kW — it is in the car's specification, not the charger's.

%

Energy that reaches the battery. The rest is heat.

Per kWh. 0 to skip the cost.

kWh/100km

Adds the range this charge buys. 0 to leave it out.

How to use the ev charging time calculator

  1. 1Enter the usable battery capacity in kWh — the usable figure from the specification, not the gross one, since a few kWh are reserved and never charged.
  2. 2Set the current state of charge and the target you want to reach.
  3. 3Pick the charger. Choosing one sets whether it is AC or DC and a sensible default efficiency; choose Custom to type a power in kW.
  4. 4On AC, enter the car's on-board charger rating. On DC, leave the taper modelling on unless you specifically want the flat figure.
  5. 5Add an electricity price and your consumption to see the cost and the range the charge buys.

Examples

Overnight on a home wallbox

Input
60 kWh battery, 20% to 80%, 7.4 kW wallbox, 7.4 kW on-board, 88% efficient
Result
5 h 32 min, 36 kWh into the battery, 40.9 kWh drawn from the meter

The 4.9 kWh difference is heat, and it is what you are billed for on top of what the car receives.

The car, not the charger, is the limit

Input
40 kWh battery, 10% to 90%, 22 kW three-phase wallbox, 3.3 kW on-board
Result
10 h 46 min at 3.3 kW — the other 18.7 kW is never drawn

A frequent and expensive surprise: a faster wallbox cannot help a car whose on-board charger is small.

Why nobody waits for 100% on a rapid charger

Input
77 kWh battery, 10% to 100%, 150 kW DC, taper modelled
Result
About 1 h 36 min, of which the last 20 per cent is roughly half

The same car goes 10% to 80% in around 29 minutes. Stopping at 80% and driving on is almost always faster overall.

About the ev charging time calculator

The formula, and the direction losses run in

Energy into the battery is the capacity multiplied by the change in state of charge: a 60 kWh pack from 20 to 80 per cent takes 36 kWh. Time is that energy divided by the power actually being delivered, adjusted for efficiency — and the adjustment goes one way only. Because charger power is measured at the supply, losses mean more energy has to be drawn than the battery receives, so they make the charge take longer, not shorter.

That direction is the easiest thing to get backwards, and the mistake is invisible: dividing by efficiency where you should multiply still produces a plausible number of hours. It is the reason this page reports the two energy figures separately rather than one — the kWh that reaches the battery, and the larger kWh that leaves the meter.

Modelling the taper without pretending to know the curve

Ignoring the taper is not a small optimism on a full charge, it is wrong by roughly a factor of two, which is worse than giving no answer at all. Modelling it exactly is not possible either, because the real curve depends on the model, the chemistry, the temperature and the pack's age, and none of those can be known from what you type.

So the model here is a straight-line decline in power from the taper point down to a fraction of the rated figure at 100 per cent, integrated over the charge. That is a genuine approximation and the page says so, but it is far closer than a flat calculation, and it reproduces the property that actually matters for planning: the sharply diminishing return on every minute spent above eighty per cent.

What this cannot know

Temperature dominates everything else and is not an input, because a useful answer would need the pack temperature rather than the air temperature, and the car knows that figure while you do not. A cold pack on a rapid charger may accept half its rated power until it warms, which is what preconditioning — heating the battery on the way to the charger — exists to avoid.

Three more are outside the arithmetic. State of health, since an older pack has both less capacity and lower acceptance. Charger sharing, because two cars on one cabinet often get half the rated power each. And billing, as many rapid networks charge by connection time as well as by energy, so the slow final stretch above eighty per cent is expensive twice over.

None of these are guessed at here. Where a figure cannot be derived from what you entered, this page leaves it out and says so rather than filling the gap with an assumption you would have no way to check.

Frequently asked questions

Why does my car charge slower than the wallbox is rated for?
Because on alternating current the conversion happens inside the car, and the unit that does it has a rating of its own. That on-board charger is a hard ceiling: plug a car with a 3.3 kW unit into a 22 kW supply and it draws 3.3 kW, leaving the rest untouched. Owners routinely blame the wallbox or the installation for this, and upgrading either changes nothing. Direct current charging sidesteps it entirely, because the conversion happens in the roadside cabinet instead, which is a large part of why it is so much faster.
What is the taper, and why is 80 per cent the number everyone mentions?
A lithium pack cannot accept full current when it is nearly full, so the battery management system reduces the power progressively as the cells fill, protecting them from damage and heat. The reduction is steep enough that the last fifth of a rapid charge can take as long as the first three fifths. Eighty per cent is where the curve typically turns sharply for most cars, which is why rapid charging is quoted as a 10 to 80 time rather than a 0 to 100 one, and why the practical advice on a long drive is to stop twice for short charges instead of once for a long one.
How accurate is this?
Close enough to plan around, and not close enough to rely on to the minute. The energy arithmetic is exact, and the on-board limit is a real hard ceiling, so an AC estimate on a mild day is usually within a few per cent. The taper model is an approximation of a curve that differs by model, by cell chemistry and by state of health, so treat a rapid-charging estimate as indicative. Temperature is the largest unknown of all: cold cells accept far less current, and a winter session without preconditioning can take close to twice as long as this page suggests.
Is the energy cost based on what enters the battery or what leaves the meter?
What leaves the meter, which is the larger of the two and the one you are billed for. Charging is lossy — the conversion, the cabling and the battery's own internal resistance all give off heat — so if 36 kWh reaches the battery at 88 per cent efficiency then about 41 kWh has come out of the supply. Costing the smaller number would understate every bill by the loss, typically 6 to 12 per cent, and that error compounds over a year of home charging into a real amount of money.
Should I use the gross or the usable battery capacity?
The usable one. Manufacturers quote both, and the gross figure includes a buffer at each end that the car never lets you touch — it exists to stop the cells being fully emptied or fully filled, which is what shortens their life. A 64 kWh gross pack might make 58 kWh available. Using the gross number stretches every estimate on this page by the difference, and it is also why a car showing zero per cent still has energy in it, and why nothing here should be read as a licence to run one flat.

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