When I first started flying with a duffel bag instead of a suitcase, I quickly realized that airline size rules can be tricky. A few inches too big and suddenly you’re paying extra fees at the gate. In this guide, I’ll walk through the most common questions travelers ask about duffel bag sizes, so you can pack smarter and avoid surprises at the airport. Part 1. What is the standard carry-on duffel bag size? Most airlines allow carry-on bags up to 22 x 14 x 9 inches (56 x 36 x 23 cm). A duffel bag that fits within these dimensions can usually be used as a carry-on. Since duffels