WASHINGTON (ABC) -- AirfareWatchdog.com founder George Hobica has logged hundreds of thousands of airline miles, but even he can be stumped by the carry-on size and weight limits.
Just before boarding a recent American Airlines flight, Hobica was told he couldn't take his carry-on luggage on board, even though he had carried the same bag on the same airline many times before.
"I was rejected. I was sent back to the check-in line because one dimension was 1 inch over the limit," Hobica said.
With rules varying among different airlines, experts recommend checking with companies on their carry-on bag restrictions before flying. Most allow travelers to bring on free carry-on bags, but mistaking the size can be a hit to the wallet.
For Hobica, he nearly missed his flight because he had to return to the ticket counter.
On American Airlines, U.S. Airways, Delta Airlines and United Airlines, the carry-on bag dimensions can't exceed 45 inches - that's the total of the length, width and height.
On Southwest Airlines and JetBlue, bags are restricted to 50 inches. Alaska Air is even more generous, allowing bags up to 51 inches.
"If you exceed any of those dimensions by one inch you could be sent back from the gate or the TSA line to check your bag and pay a fee," Hobica warns.
For Marvin Wheeler, a businessman who flies to D.C. weekly and tries to always carry-on his luggage, "now you have me nervous that it won't fit in."
"I would die if they made me start checking in this size," he concluded.