Most people know the airline rules: you’re allowed one carry-on bag and a personal item.

And for most airlines, the size of those carry-on bags is restricted to 22 inches by 14 inches by 9 inches. But remember, the airlines count the wheels of the bag as part of the complete allowed dimensions. Some airlines even limit the weight of those carry-on bags.

Frontier allows up to a generous 35 pounds for a carry-on bag, but remember, the airline charges for carry-ons. Hawaiian Airlines’ limit for that free carry-on is 25 pounds.

Allegiant Airlines also has a 25-pound allowance, but that’s only after you pay for the bag.