Airplane mode helps charging by making your phone do less

Why fewer wireless tasks can help

A phone does not send every watt from its charger straight into the battery. While charging, it also runs the screen, processor, and radios. The cellular radio may repeatedly communicate with nearby towers, especially when reception is weak; Wi-Fi and Bluetooth can also remain active. Those tasks consume some of the power coming in.

Airplane mode cuts off cellular service and can reduce that background radio activity. With less power being used to stay connected, more of the charger’s output can go toward replenishing the battery. The effect is most noticeable when the phone would otherwise be working hard to maintain a poor connection.

Why the speedup has limits

Airplane mode does not make the charger deliver more power. Charging speed is also controlled by the phone and charger, and it can slow as the battery fills or the device warms up. A bright screen, demanding apps, or heat may matter more than wireless activity. Some phones also let you turn Wi-Fi or Bluetooth back on while airplane mode is active, so those connections may still use power.

For the best chance of a quicker charge, switch on airplane mode and leave the screen off; if the phone is already cool and has a strong signal, the difference may be small. The practical gain comes from reducing what the phone does while plugged in—not from changing the battery or charger.