Does a charger left plugged in still use power?

Inside a charger is a circuit that turns the 220 volts from the wall into the low voltage a phone needs. Even with no phone connected, that circuit doesn't switch off. It stays ready, so a tiny trickle of electricity keeps flowing. This is called standby power.

Since April 2020, an EU regulation has capped this power at 0.1 watts for chargers rated 49 watts or less. At 0.1 watts over the 8,760 hours in a year, that comes to about 0.9 kilowatt-hours. That's roughly the same as charging a phone battery from empty to full a few dozen times, and on a household electricity bill it works out to a few hundred won.

The idea that a plugged-in charger secretly eats a lot of electricity wasn't entirely wrong if you think of old chargers. Earlier standards were several times looser, and big, heavy old chargers stayed fairly warm even on standby. Today's chargers put their circuit into a resting state once the phone is unplugged, so most of them feel cool to the touch.

These days, the bigger standby users at home aren't chargers but devices like set-top boxes, which keep waiting for a signal even when the screen is off, and appliances that are left on for long stretches. If you want to save electricity, switching off those devices all at once with a power strip that has a switch does far more than unplugging a single charger.

What matters more than the electricity bill is safety. When dust builds up between the plug and the socket and picks up moisture, current can leak across it and start a fire. This is called tracking. The longer a plug stays in the socket, the more dust tends to collect, so it helps to unplug it now and then and wipe it with a dry cloth.

If a charger feels noticeably warm even with no phone connected, if the cable's coating is worn through, or if the plug sits loosely, it's best to unplug it right away and replace it. It's also important not to charge in places where heat can't escape, such as under a blanket. And when you'll be away from home for a long time, unplugging gives you peace of mind.