Figures are estimates based on typical UK market rates and manufacturer data — your real numbers will vary with weather, speed, and driving style. Looking for the US version?
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Charging cost depends on how much energy your battery needs (measured in kilowatt-hours, or kWh) and what that energy costs at the source. This calculator multiplies the kWh you're adding by your electricity rate to get a cost, and divides the same kWh by charger speed to get a charge time.
The energy needed is your battery size in kWh multiplied by the percentage-point gap between your current and target charge (e.g. a 60 kWh battery going from 20% to 80% needs 60 × 0.6 = 36 kWh). Cost is that kWh figure multiplied by your rate in pence per kWh. Charge time is the same kWh figure divided by the charger's effective speed — whichever is lower of the charger's own rating and your car's maximum charge rate, since a car can't charge faster than its onboard charger allows even on a more powerful unit. Rapid and ultra-rapid chargers also slow down above roughly 80% to protect the battery, so the estimate above that point runs a little optimistic — the calculator flags this with a warning when it applies.
Electricity cost varies a lot by where you charge. Home charging on an off-peak overnight tariff is cheapest, typically around 7p/kWh. Home charging on a standard daytime tariff runs closer to 24p/kWh. Public charging costs more because the operator has to cover hardware, installation and running costs — public slow/destination chargers average around 45p/kWh, public rapid chargers (50kW+) around 68p/kWh, and manufacturer-run supercharger networks around 43p/kWh. Picking a charging location above sets the rate slider to that type's typical figure, which you can then drag to match your own actual tariff.
The miles you get per kWh isn't fixed — it depends on how and where you drive. City driving is the most efficient because frequent braking recovers energy back into the battery through regenerative braking. Motorway driving at sustained higher speeds is the least efficient, since aerodynamic drag rises sharply with speed and there's little opportunity to regenerate. This calculator applies a multiplier to your car's baseline efficiency depending on which driving style you select. Cold weather, cabin heating and towing all reduce real-world range further, on top of the driving-style adjustment — typically by 20–30% in winter conditions, which the range panel flags separately.
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