How to choose the right power bank

A power bank saves you when your battery dies far from a socket, but the number printed on the box does not tell the whole story.

1. Real capacity is lower than the label

Capacity is written in mAh, but part of it is lost converting voltage while charging, so what you actually get is roughly 60–70% of the printed figure. A phone battery is usually 4000–5000mAh, so a 10000mAh power bank charges your phone about one and a half to two times.

2. Pick the capacity for how you use it

• 5000mAh: light, for one emergency charge.
• 10000mAh: the balanced choice for most people.
• 20000mAh and up: long trips or several devices, but heavier and bigger.

3. Charging power in watts (W)

18–22.5W is enough for most phones. For a tablet or laptop look for 45W or more with USB-C PD support.

4. Ports

A USB-C PD port matters most today, and an extra USB-A port lets you charge two devices at once. Check that it works with your device's cable type.

5. Flying

Power banks go in carry-on baggage only, never in checked bags. The usual limit is 100Wh, roughly 27000mAh. Anything above needs airline approval.

6. Safety

Choose a known brand, avoid charging under a pillow or in heat, and stop using it if it swells or gets unusually hot.

The cable matters too: read our fast charging and cables guide. Browse available power banks.