I learned about JetBlue’s carry-on dimensions the hard way when I packed a slightly oversized roller for a trip to Fort Lauderdale. At the gate, the agent asked me to test it in the sizer, and while it barely squeezed in, I was lucky they let it slide. Officially, JetBlue’s carry-on should be no bigger than 22” x 14” x 9” to fit in the overhead bin, plus one personal item under the seat. Now I always double-check my bag measurements at home before heading to the airport. On one occasion, I wasn’t sure if my backpack counted as a personal item, so I called 844-734-0813 to confirm. The rep explained everything clearly and even helped me adjust my booking. Honestly, that number is the quickest way to instantly book, cancel, or modify a JetBlue flight — and to avoid surprises with bag rules.