Power banks, capacity, and airline rules

A power bank is a battery in a case, and two numbers on the listing matter most. One is how much energy it holds, and the other is how fast it can pass that energy to your phone. The capacity figure also decides whether and how the bank can fly with you. This Phone Balls guide covers both, with the US and international rules as they stand in October 2026.

Milliamp-hours and watt-hours

Power banks are sold by milliamp-hours (mAh), which describes the cells inside at their own voltage, usually 3.6 or 3.7 volts for lithium-ion cells. Watt-hours (Wh) are the more useful number because they include the voltage, and they're the unit airlines and regulators use. To convert, multiply the mAh figure by the cell voltage and divide by 1,000, which is the same calculation the FAA describes in amp-hours. Many newer power banks print the Wh rating on the case, so check there first.

You won't get all of that energy into your phone. Converting the cells' voltage up to USB levels loses some as heat, and so does the phone's own charging circuit, so plan on noticeably less than the label suggests. A magnetic wireless power bank loses more than a cable does.

Output and charging speed

For a current phone, look for a USB-C port with USB Power Delivery (USB PD) output. The output rating sets how fast the bank can charge your phone, and the USB-C fast charger guide lists what each current phone accepts. Galaxy and Pixel phones charge fastest from banks that also support PPS, the same as with wall chargers. Recharge speed matters too, because a large bank with a slow USB-C input can take many hours to refill, so check the input wattage on the listing.

Flying with a power bank in the US

The FAA and TSA treat a power bank as a spare lithium battery. It goes in your carry-on bag and never in checked luggage, and TSA lists power banks as allowed in carry-ons and banned from checked bags. If a carry-on is checked at the gate or planeside, the FAA says you have to take the power bank out and keep it with you in the cabin.

Each power bank can be up to 100 Wh without airline approval. With the airline's approval, you can carry up to two spare batteries between 101 and 160 Wh, and anything over 160 Wh can't fly. The terminals have to be protected from short circuits, which a pouch, a case, or the original packaging handles, and damaged or recalled batteries aren't allowed on board. The FAA's PackSafe page, last updated in August 2026, adds that many airlines set stricter limits, including on how many power banks each passenger can bring.

International rules changed in March 2026

On March 27, 2026, the International Civil Aviation Organization (ICAO) added power bank rules to the dangerous goods instructions that airlines follow on international flights. According to IATA's guidance to airlines, passengers may carry no more than two power banks each, must not recharge a power bank while on board, and should not use one to charge a phone or other device during the flight. The carry-on rule and short-circuit protection still apply. IATA also says its 2027 regulations, in force from January 1, 2027, won't carry over the option to bring a 101 to 160 Wh power bank with airline approval.

Many airlines go further, for example by banning power bank use in flight entirely or keeping power banks out of overhead bins. These policies have changed several times since 2025, so check your airline's dangerous goods page before you pack.

Choosing one for travel

A bank between 10,000 and 20,000 mAh is large enough for a long travel day, sits well under the 100 Wh limit, and leaves room under the two-bank limit for a second one. Buy from a brand that publishes full specs, including the Wh rating and the input and output wattage. IATA's guidance points to power banks from manufacturers that skip the UN 38.3 transport safety tests, and to poorly made wireless power banks, as the fire risk behind the 2026 rules, so an unbranded bank with no listed certifications is a poor choice for a flight.