You can travel with your pet carrier and 1 personal item, but you will not be allowed to bring a carry-on bag in addition to a pet carrier and a personal item. American Airlines pet carrier size It's the carrier for small dogs and cats. This is a portable baby carrier that can be folded to reduce its size for easy travel. Pets must fit inside a 19” x 13” x 9” (or 48 cm x 33 cm x 22 cm) cage and the weight of the pet plus cage should be around 25 pounds. All pets must be at least eight weeks old to travel.