EV Charging Time Calculator
Estimate how long an electric car takes to charge from one battery percentage to another, based on battery size, charger power, and charging efficiency, plus the cost.
Comment utiliser cette calculatrice
- 1Enter your car's battery capacity in kWh.
- 2Enter the charger's power — home chargers are usually 7–22 kW, rapid chargers 50 kW and up.
- 3Enter your current and target charge percentages.
- 4Read the estimated charging time and, if you set a price, the cost.
Comment ça marche
EV charging time
energy to add = battery capacity × (target % − current %) time = energy to add ÷ (charger power × efficiency) energy from grid = energy to battery ÷ efficiency cost = energy from grid × price per kWh
Estimating how long an electric vehicle takes to charge starts with how much energy you need to add: the battery's capacity in kilowatt-hours multiplied by the percentage of charge you want to gain. Dividing that energy by the power of the charger, in kilowatts, gives a time in hours — a bigger battery or a smaller charger means a longer wait. Charging is not perfectly efficient, though; some energy is lost as heat in the charger, cables, and battery, so the effective power reaching the battery is a bit less than the charger's rating, which is captured by an efficiency factor. That same loss means the grid supplies more energy than ends up stored, which matters for cost: the electricity billed is the energy drawn from the grid, found by dividing the battery energy by the efficiency, times the price per kilowatt-hour. The result is a straightforward estimate, though real charging is more complex because the rate changes as the battery fills.
Exemple détaillé
Charging a 60 kWh battery from 20% to 80% adds 60% of its capacity, or 36 kWh. On a 7.4 kW home charger at 90% efficiency, the effective power is about 6.7 kW, so the charge takes roughly 5 hours 24 minutes — a typical overnight home charge. At 15 cents per kWh it costs about $6 for the 40 kWh drawn from the grid.
EV Charging Time Calculator : le guide complet
What determines charging time
Charging time comes down to a simple relationship: how much energy you need divided by how fast you can deliver it. The energy needed depends on the battery size and how much of it you want to fill — going from nearly empty to full on a large battery is a lot of energy, while topping up a small gap is quick. The delivery speed is the charger's power, and this is where the biggest differences arise. A standard home socket trickles in a couple of kilowatts, a dedicated home or workplace charger delivers 7 to 22, and public rapid chargers push 50 to 350 kilowatts, spanning a range from overnight to minutes.
A crucial subtlety is that the slower of two limits governs the real rate: the charger's output and the car's maximum acceptance. Plugging a car that can only accept 7 kW into a 150 kW rapid charger does not make it charge at 150 — it charges at 7. Conversely, a car capable of rapid charging is throttled by a slow charger. So the effective power is whichever is lower, the car or the charger. This is why knowing both your vehicle's charging capability and the charger's rating matters, and why the fastest possible charge requires a car and a charger that are both up to it.
Why real charging is slower than the simple estimate
The straightforward calculation of energy divided by power gives a useful ballpark, but real-world charging is slower and more complex, chiefly because the charging rate is not constant. Batteries charge fastest when relatively empty and slow down as they fill, a behaviour dictated by battery chemistry to avoid damage and overheating. This tapering is dramatic on rapid DC chargers: a car might pull its full rated power up to around half or two-thirds full, then progressively slow, so the last 20% can take as long as the first 60%. This is precisely why rapid-charging advice centres on stopping at about 80% — beyond that, the wait per added mile becomes uneconomic.
Efficiency losses add to the gap between theory and reality. Energy is lost as heat in the cables, the onboard charger that converts AC to DC, and the battery itself, so not all the power drawn from the wall reaches the battery — typically 85 to 95% does. Cold weather makes it worse, both by reducing efficiency and by prompting the car to warm the battery, which consumes energy and slows charging further. Temperature, the battery's state of health, and the charging management system all influence the real rate. The calculator's steady-rate estimate is a reasonable guide for slower AC home charging, where the rate is fairly constant, but it will understate the time for a rapid charge to a high state of charge.
Cost, convenience, and charging habits
Beyond time, charging has a cost, and the two are linked to how and where you charge. Home charging is usually far cheaper than public rapid charging, especially on overnight or off-peak electricity tariffs, and it is where most EV owners do the bulk of their charging. Because the electricity is billed on the energy drawn from the grid — which includes the efficiency losses — the cost reflects a little more than the energy stored in the battery. Even so, charging at home overnight typically costs a fraction of what an equivalent tank of petrol would, which is one of the main running-cost advantages of an electric car.
The practical rhythm of EV ownership tends to favour slow, frequent top-ups over occasional full charges. Plugging in at home each night to add the day's driving is convenient and gentle on the battery, and it means the car is usually ready without the driver ever waiting around. Rapid charging is reserved for long journeys, where the taper and the higher cost are accepted in exchange for speed. Understanding charging time helps plan both: knowing an overnight home charge comfortably restores a daily commute, and estimating how long a rapid stop adds enough range for the next leg of a trip. The calculator supports both kinds of planning, from the routine overnight charge to the motorway rapid-charge stop.
Questions fréquentes
How long does it take to charge an electric car?
It depends on the battery size, the charger power, and how much charge you're adding. A 60 kWh battery from 20% to 80% (36 kWh) takes about 5.5 hours on a 7.4 kW home charger, but under an hour on a 50 kW rapid charger. Divide the energy needed by the effective charging power.
Why does charging slow down near full?
Battery chemistry requires a slower rate as the battery fills, to avoid overheating and damage. On rapid chargers the taper is dramatic — the last 20% can take as long as the first 60%. That's why the common advice is to rapid-charge only to about 80%.
Does the charger or the car set the speed?
Whichever is slower. A car that accepts only 7 kW charges at 7 kW even on a 150 kW rapid charger, and a rapid-capable car is limited by a slow charger. The effective rate is the lower of the car's maximum acceptance and the charger's output.
How much does it cost to charge an EV?
Multiply the energy drawn from the grid (the battery energy divided by charging efficiency) by your electricity price. Adding 36 kWh to the battery at 90% efficiency draws about 40 kWh; at 15 cents/kWh that's about $6. Home overnight charging is usually far cheaper than public rapid charging.