The size limits for carry-on luggage may vary every so slightly from airline to airline, so it’s best to check the exact specifications of your flight carrier before heading to the airport. But 22” x 14” x 9” is usually the standard size of a carry-on bag on a domestic flight. For international flights, it’s best to score a suitcase 21” or less to ensure you meet the requirements of the airline (and any regional airlines you may travel with while abroad).