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Calculator / Realistic Charging Time
Charging taper

Realistic Charging Time

Compare a flat-rate estimate with a simple taper model for charging above 80%.

The car’s usable battery capacity in kWh. Use the usable—not gross—figure from the vehicle specification.
The battery percentage when the charging session starts.
The battery percentage you want to reach. Charging above 80% can take disproportionately longer on a rapid charger.
The charger’s advertised maximum output in kW, such as 7.4 kW at home or 150 kW at a rapid charger.
The maximum power your vehicle can accept from this type of charger. The estimate uses whichever is lower: charger or vehicle.
Electricity lost while charging. Leave at 10% if you do not have a measured figure.
This is an illustrative average taper model. Actual curves vary substantially by vehicle, battery temperature and charger.

Why rapid charging slows as the battery fills

The charger’s headline kW rating is only its maximum capability. The vehicle controls how much power it accepts, and the rate usually changes throughout a DC charging session. It commonly falls at a higher state of charge to protect the battery.

Ideal versus realistic time

The ideal figure assumes the effective maximum power continues throughout. The tapered estimate applies a reduction above the selected threshold, giving a more useful planning comparison.

Why two cars differ on one charger

Battery temperature, voltage architecture, charging curve and starting percentage can cause different speeds even when both cars use the same rapid charger.

To see whether home charging finishes before an off-peak tariff ends, use the cheap-rate window calculator.