If you leave your charger plugged into the socket without a device connected, it will, in most cases, consume a very small amount of power. This amount of power, also known as standby consumption, can add up if it remains unnecessarily plugged in for a long time.

The exact cost depends on the energy price per kilowatt-hour (kWh) and the duration of the unnecessary power consumption. In general, you can expect that the usage of an unused charger will have a negligible effect on your energy bill. However, it is still a good practice to unplug chargers when not in use, both to save energy and to reduce potential safety risks.