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EV charging cost calculator

What a charge actually costs, on your tariff and your car. Includes charging losses, which most calculators quietly leave out and which add roughly a tenth to every bill.

This charge costs

£2.80

Energy into the battery
36 kWh
Drawn from the grid
40 kWh
Lost as heat
4 kWh
Range added
144 miles
Cost per 100 miles
£1.94

An estimate in GBP, for United Kingdom.

What this assumes

  • Charging efficiency of 90% — energy is lost as heat in the charger, cable and battery, so the grid always supplies more than the battery receives.
  • State of charge 20% → 80%.
  • Standing charges, session fees and idle fees.
  • Your electricity standing charge is excluded — you pay it whether or not you charge.
  • This is an estimate. Real cost varies with temperature, charging speed and how the tariff bills part-hours.

How this is worked out

Three steps, no hidden factors:

energy added = usable capacity × (target SOC − start SOC)
grid energy  = energy added ÷ charging efficiency
cost         = grid energy × unit price

The middle step is the one most calculators skip. Charging is not lossless — around a tenth of what you pay for never reaches the battery.

For the wider picture on why the same charge can cost ten times as much depending on where you plug in, see the £7 fill-up.

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