Airlines have been enforcing size and weight limits more strictly now than in the past. If you show up and your luggage is too big they will force you to check them which can result in extra fees or charges.
The FAA limits passengers flying within the United States to one piece of carry-on luggage and one personal item. Personal items may include leather backpacks, handbags, or leather briefcases. In addition to a carry-on and personal item, passengers are also allowed to bring a jacket, a book, a small bag of food and medical devices such as walkers, etc.
Carryon Size = 45 Linear Inches
Be sure to check with your airline first, but most domestic carriers permit carry-on bags that are 45 linear inches. To figure out a bags "linear inches" you have to sum the bags length, width and height. For example, the Venezia Duffle Bag measures 21" x 11" x 10" - > its measurement in linear inches is 20 + 11 + 10 = 42 inches, so it would be allowed.
Measurements include the handles and wheels. Most of our rolling trolley bags like the Venezia Trolley, FC Pull Trolley and FC Push Trolleys are carryon size. The Milano Trolley size Small is carryon size but the Large size is 50 linear inches and if you travel with this particular size the airlines may require you to check it. We include the wheels and handles in our measurements to make it easy to calculate.