So, how big can your duffel bag be? Well, it really depends on the airline, but most have similar size restrictions. For example, American Airlines allows duffel bags up to 62 linear inches (that's length + width + height, for those who are math-challenged), while Delta allows up to 80 inches.
But here's the thing: even if your duffel bag meets the size requirements, it still has to fit in the cargo hold. So, if you've got a giant duffel bag that's shaped like a cylinder, it might not fit, even if it's technically within the size limits. It's like trying to squeeze a square peg into a round hole, or in this case, a duffel bag into a cargo hold.
Can A Checked Bag Be A Duffel Bag at Nichelle Hock blog
And then there's the issue of weight. Most airlines have a weight limit for checked bags, typically around 50 pounds. But, some airlines, like Emirates, will let you check a duffel bag that weighs up to 70 pounds, which is like, a lot of heavy stuff. Just don't try to sneak any anvils or lead weights in there, or you might find yourself in trouble.
