Airline Restrictions: New Limits on Both Carry-on and Checked Baggage

In many cases, the airlines have added new limits on both carry-on and checked baggage. Most airlines limit their carry-on bags to a range of 8" to 9" high, 14" to 16" wide and 21" to 24" high, and to weight limit of 40 pounds and a checked baggage weight limit of 70 pounds. These limits vary and are much strictly imposed than earlier. Since the airlines' restrictions are experiencing the period of change, you will need to check with your airline as to size, weight and number of bags you can carry.
Even if you sneaked it on once, don't always expect to be that lucky. More stringent enforcement of the rules and more and more bag size stations will likely catch up with you. This is especially likely on holidays and other peak flying times when the airlines are watching closely, as the planes are full and everyone is trying to drag lots of stuff on the plane.
Most airlines allow for combination of three bags to be divided among your carry-on and checked luggage. However, different airlines look at some things differently – some will count a notebook against your allowance, while others will not. So, be sure to check out with the particular airline.