Power Banks on Flights: Capacity, Quantity and Storage Rules

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Power banks can travel in the cabin, but must not go in checked baggage. On flights departing Hong Kong, each passenger may carry no more than two power banks, and recharging them during the flight is prohibited. Cathay Pacific and HK Express also prohibit using a power bank to charge your phone or storing it in an overhead compartment. When packing, check capacity, quantity and storage together.

Departing Hong Kong: How Many Can You Bring, and Where Should They Go?

The Hong Kong Civil Aviation Department’s current requirements apply to all flights departing Hong Kong International Airport: a maximum of two power banks per passenger, carried in the cabin only. Two is the total limit, rather than two large power banks plus a small one. Sharing a cabin bag with a travelling companion does not remove the individual limit.

Airlines may impose additional restrictions. Cathay Pacific and HK Express, for example, require the following:

• Keep power banks out of checked baggage.
• Do not recharge a power bank on board or use it to charge or power another electronic device.
• Do not leave it inside cabin baggage in an overhead compartment. Follow the airline’s instructions to store it in a personal bag under the seat in front or another designated location.

Before departure, check the Hong Kong Civil Aviation Department’s notice and the operating airline’s rules. Different airlines may operate each leg of a connecting itinerary, so check the actual operators rather than just the booking platform.

Check Capacity in Watt-hours, Not Just Milliamp-hours

Figures such as 10,000mAh and 20,000mAh describe capacity, while aviation rules commonly use watt-hours, or Wh. The calculation is:

Wh = mAh ÷ 1,000 × nominal cell voltage in volts

All examples below assume a nominal cell voltage of 3.7V:

Labelled capacityCalculationWatt-hours10,000mAh10,000 ÷ 1,000 × 3.737Wh20,000mAh20,000 ÷ 1,000 × 3.774Wh30,000mAh30,000 ÷ 1,000 × 3.7111Wh

Start with the Wh rating and cell specifications printed on the product itself. A USB output of 5V or 9V is not the nominal cell voltage, and “100W fast charging” describes power rather than a capacity of 100Wh. Use the product’s actual cell voltage instead of assuming every model is 3.7V.

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Can You Always Get Approval for a Power Bank Between 100Wh and 160Wh?

A rule allowing approval for lithium batteries up to 160Wh does not automatically mean a power bank is accepted. Check the quantity, use and capacity rules for power banks separately from those for other spare batteries.

HK Express currently requires power banks and the relevant spare lithium-ion batteries to be no more than 100Wh. The 111Wh example above exceeds that limit. Cathay’s information lists small spare lithium batteries as below 100Wh and sets separate conditions for medium-sized batteries. Those conditions alone do not establish acceptance of any power bank between 100Wh and 160Wh.

ICAO’s technical guidance provides for power banks exceeding 100Wh but not exceeding 160Wh with approval from the operating airline. Airlines can apply stricter limits. For a higher-capacity model, obtain explicit confirmation covering a power bank, rather than relying on approval for a spare camera or laptop battery. Lower-capacity models must also meet the labelling, condition and quantity requirements.

How Should You Pack and Protect a Power Bank?

1. Check the label: Keep the Wh rating, or capacity and voltage information, clearly legible. Cathay explicitly refuses lithium batteries without a clear capacity rating.
2. Protect each one separately: Use the original packaging or a protective case. Insulate exposed terminals where necessary to prevent short circuits from contact with keys, coins or other metal objects.
3. Keep it accessible in a personal bag: Once on board, follow the airline’s storage instructions and disconnect cables linking it to other devices.
4. Remove it if your cabin bag is checked at the gate: Take the power bank out and keep it in the cabin. Clearing security does not make it suitable for the aircraft’s hold.

Do not bring a swollen, damaged or abnormally hot power bank to the airport. Check whether the manufacturer has recalled the model or batch. If you notice a problem on board, tell the cabin crew immediately rather than putting it back in your bag or taking it apart.

Do You Need a 3C Mark When Travelling to Mainland China?

Mainland domestic flights have a separate requirement. From 28 June 2025, power banks without a 3C mark, with an unclear mark, or belonging to a recalled model or batch are prohibited. If your itinerary includes a mainland domestic flight, prepare for that segment’s requirements too. See the Civil Aviation Administration of China’s notice.

This is separate from Hong Kong’s departure quantity limit and airline capacity rules; it is not a blanket 3C requirement for every flight leaving Hong Kong. A 3C mark also does not override capacity, condition or quantity limits.

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