What size power bank can I bring on a plane?

The TSA and most international airlines cap lithium battery carry-on at 100Wh per pack. That works out to roughly 27,000mAh at 3.7V — every pick on this list is marketed as flight-approved, with the Anker Prime 26K specifically rated at 99.75Wh to stay just under the limit. Anything larger generally requires airline approval.