Guides

Charging losses, explained

The dashboard and the electricity meter do not always measure the same quantity. A fair cost comparison needs the kilowatt-hours you pay for.

What does “10% loss” mean here?

In this calculator, 10% of energy at the meter is lost during charging: of 20 kWh, 18 kWh reaches the battery. We therefore divide 18 by 0.9. Adding 10% to 18 gives 19.8, which would use a different definition.

Do not count losses twice

If your consumption comes from measured billed electricity divided by distance, it already includes charging losses. Set the calculator’s loss to 0%. The same applies to a figure explicitly measured from the mains. Check the measurement boundary of your source.

Why an editable value?

Losses depend on the vehicle, charging power, temperature and auxiliary loads. The default 10% is only an example assumption. Use your own measurements if available. The calculator uses one common loss value for the entire charging mix.

Measure over a useful period

Compare billed electricity with distance driven over a sufficiently long period. Different battery levels at the start and end can distort the result. Aim for the same or similar starting and ending charge levels.