Even if you have your packing strategy down to a science, you've probably had at least one run-in with a bulging carry-on bag that won't fit into the overhead bin as a flight attendant glares at you. Even worse, you may have been forced to gate check when your hard-case roller didn't fit snugly in the dreaded measurement box. Did the airline website understate how seriously gate agents would take size limits, or did you flat-out forget to check? To add to the confusion, restrictions vary by airline and even ticket class—meaning that suitcase you seamlessly brought on board for one flight might be gate checked on another.

https://www.afar.com/magazine/a-guide-to-carry-on-luggage-size-restrictions

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