How does the calculator know the charging power curve?

Once you pick a model from the EvCompass catalogue, its usable battery capacity and charging power curve fill in automatically — there is no spec to type in yourself.

Why does the post I pick change the time so much?

A post never delivers more power than its own rating, even when the car's curve would allow more at that moment. On a 50 kW post, a car capable of 150 kW still charges at a speed capped at 50 kW for the whole session.

Is the power curve measured by the manufacturer?

No. When the curve is calibrated, it means we shaped it to match ONE claimed figure from the manufacturer's own data (e.g. 85 kW, 0-80%, 35 min) — that is one data point, not a measured charging run. Where no such figure exists, the curve is entirely estimated from the car's specs instead. Neither one is a measurement.

EV calculators

Charging time

Pick a model from the catalogue, set the charge window, and see how long the session actually takes at a given charging post's power.

Start of charge (%)

The state of charge you start the session from.

End of charge (%)

The state of charge you end the session at.

Charging post power

The post's maximum rated power — the car never draws more than this, even where its own curve would allow it.

Custom station power (kW)

Enter the station's real rating if it differs from the three typical values above — e.g. the power printed on a specific charger's spec sheet.

BMW i5 xDrive40 Sedan (2025) · curve calibrated to the claimed window 205 kW, 10–80%, 30 min

Charging time: 28 min
Energy delivered: 48.7 kWh
Average power: 103.6 kW
Range added: 278 km

curve calibrated to the claimed window 205 kW, 10–80%, 30 min

Car's own power curve
Power delivered at this post

The car's own power and the power actually delivered at the chosen post, by state of charge
State of charge	Car's power	Delivered power
10%	192 kW	150 kW
14%	192 kW	150 kW
17%	192 kW	150 kW
21%	192 kW	150 kW
24%	192 kW	150 kW
28%	178 kW	150 kW
31%	163 kW	150 kW
35%	149 kW	149 kW
38%	135 kW	135 kW
42%	120 kW	120 kW
45%	106 kW	106 kW
49%	103 kW	103 kW
52%	100 kW	100 kW
56%	97 kW	97 kW
59%	94 kW	94 kW
63%	90 kW	90 kW
66%	86 kW	86 kW
70%	82 kW	82 kW
73%	78 kW	78 kW
77%	73 kW	73 kW
80%	69 kW	69 kW

Charging time FAQ

How does the calculator know the charging power curve?: Once you pick a model from the EvCompass catalogue, its usable battery capacity and charging power curve fill in automatically — there is no spec to type in yourself.
Why does the post I pick change the time so much?: A post never delivers more power than its own rating, even when the car's curve would allow more at that moment. On a 50 kW post, a car capable of 150 kW still charges at a speed capped at 50 kW for the whole session.
Is the power curve measured by the manufacturer?: No. When the curve is calibrated, it means we shaped it to match ONE claimed figure from the manufacturer's own data (e.g. 85 kW, 0-80%, 35 min) — that is one data point, not a measured charging run. Where no such figure exists, the curve is entirely estimated from the car's specs instead. Neither one is a measurement.

Result

Charging time FAQ