A power bank is an ideal travel companion if you have a long journey ahead, but what are the rules on taking a power bank on a plane?

Power banks should not be carried in your hold (checked) luggage, but it is fine to carry a maximum of two power banks in your hand (carry-on) luggage. Each must be individually packed and no greater than 100Wh, which is around 27,000mAh.

Some airlines will allow you to take power banks up to 160Wh in your hand luggage, though anything over 100Wh must be approved by the airline. 160Wh is around 43,000mAh.

It’s important that the specifications of your power bank are printed clearly on the device, or that you retain its original packaging. If it’s an older device be sure to check that this information has not been worn away - if the airline cannot verify its specification it may confiscate the device.

How many Wh is my power bank?

The Wh rating is rarely specified on a power bank’s casing, but you can work out this figure by multiplying the mAh rating by the nominal voltage (usually 3.7V), then dividing this by 1000. You can also automate this calculation using this free site.

It’s unlikely that you’ll pack anything greater than 160Wh for the simple fact that you’ll also be restricted on weight. However, it is possible to buy power banks designed for laptops that are even greater than 160Wh.

Read next: Best Power Bank Deals