Well not a lot and no free lunch anymore, I mean checked in baggage not free on most air travel domestic and international.
The maximum combined linear measurement (length + width + height) of carry-on bags must not exceed 14 inches x 9 inches x 22 inches (23 x 35 x 56 cm) or 45 linear inches (114 cm).
In addition to one carry-on item, you may bring one personal item such as a shoulder bag, backpack, laptop bag or an item of similar size.
The following items are not counted toward your one bag and one personal item limit:
* Overcoat or wrap
* A reasonable amount of reading material
* Pet carrier (fees apply)
* A collapsible wheelchair
* Child restraint seat meeting FAA approval standards
* Diaper bag
* A limited amount of duty-free merchandise or food purchased in the airport
* Assistive devices (a cane, one set of crutches, prescription medications and any medical devices needed to administer the medications, a portable oxygen concentrator (POC), etc.)
Checked in baggage is not free on most airlines either it is domestic travel or international.
You can check the Domestic and International airlines at this link for detailed info.
Have a nice trip.