For most trips, the Anker PowerCore 10K is enough: it is slim, about 37 Wh, and gives a phone roughly two charges. Take the Anker Power Bank 20K (30 W) when you want three or four charges, or need to top up a tablet or small laptop as well. Both are far below the 100 Wh airline limit, so neither needs approval.
What the airline limit means for each
Airlines count watt-hours, not milliamp-hours. The sum is mAh × 3.7 V ÷ 1,000: the 10K comes to about 37 Wh and the 20K to about 74 Wh. Up to 100 Wh needs no airline approval, so both can go in your carry-on. Power banks never go in checked bags.
One rule is new: since 27 March 2026 you can carry at most two power banks on international flights, and you can't charge them on board. Two Anker banks, one of each size, is within that limit. Our power bank guide has the full rules and a Wh calculator.
How many charges you get
Real-world numbers are lower than the label, because some energy is lost as heat while charging. As a rule of thumb the 10K charges a recent phone about twice, and the 20K about three to four times. If you only need to survive one long travel day, the 10K is plenty. If you are away for a week without reliable sockets, or you share with a partner, the 20K is the safer buy.
Size, output and what it can charge
The 10K is the one that disappears into a jeans pocket or the seat pocket. The 20K is larger and heavier, so it lives in your personal item. The 20K is also the one with a 30 W USB-C port, which is useful for a tablet or a small laptop that charges over USB-C. Check your own device's charging needs before you rely on any power bank for a laptop. Anker's pages list the exact output for each model.
Our call
Buy the 10K if you want something light for flights and day trips. Buy the 20K if you travel for longer, travel with family, or charge more than a phone. Owning both is a sensible pair: the small one for flights, the large one for the trip.