American Airlines will charge a checked bag fee for oversized carry-on, which costs between $30 to $200 depending on your destination and how many bags you have already checked.

If your carry-on bag exceeds the dimensions allowed by American Airlines (typically 22 x 14 x 9 inches), several things can happen depending on when the discrepancy is noticed. If identified at the check-in counter, the agent will require you to check the bag and pay the applicable checked baggage fee, which is often around $30–$40 for a first bag. If you make it to the boarding gate and the agent determines your bag won't fit in the "sizer" or the overhead bins, they will perform a "Gate Check." In 2026, many gate-checked bags are sent to your final destination's baggage claim rather than being returned to you on the jet bridge. While some airlines provide gate checking for free when bins are full, American Airlines may still charge you the standard checked bag fee if the reason for checking is that your bag is oversized. To avoid this, it is critical to include wheels and handles in your measurements, as these are the most common reasons bags fail the sizer test. If you are in Basic Economy, the rules are even stricter, and you may be charged a handling fee on top of the baggage fee.