When traveling, carrying carry-on baggage makes it so much easier. First, you do not have to check in the bag, and secondly, traveling lighter costs less to travel.
JetBlue carry-on size must be able to fit in the overhead compartment bin and must not exceed 22″ L (55.88 cm) x 14″ W (35.56 cm) x 9″ H (22.86 cm). The size includes handles and wheels that are a part of the carry-on baggage.
It is best to make sure your carry-on fits in the sizer bin. JetBlue will have you check it in if the suitcase is deemed oversized, costing you money in baggage fees.