Many find that a single carry-on suitcase can be a convenient way to travel. Others prefer to take advantage of carry-on luggage because they like to keep their valuables close to them. With so many restrictions, travelers may be confused about the rules for carry-on luggage size. The size and weight remains the same across the board for most airlines. However, in the end, it's important to contact your specific airline to clear up concerns about more ambiguous items, such as wheelchairs, crutches or even a coat.

Carry-On Size and Weight

Most airlines will allow one carry-on bag along with one personal item. Maximum size for most airlines is 45 linear inches, including length plus width plus height. The maximum weight is 40 pounds or 18 kg. If your luggage is larger, it should be checked in, since no oversize luggage or package can be stowed aboard, according to the FAA. Each item must fit in an overhead bin or underneath the seat right in front of you, says Delta.

Personal Items

A personal item can be purses, briefcases, camera cases, diaper bags, laptop computers and other items similar to this size (Delta). Because of security measures, wrapped packages receive the same treatment by airport security as carry-on baggage, so leave packages unwrapped (Continental).

Other Items

You can also bring the following aboard: food items that are for the purpose of immediate consumption, assisting devices such as crutches or wheelchairs, duty-free merchandise in a box or bag, a jacket, coat or umbrella. The categories to which these items belong vary according to the airline, so check your own carrier to see if these items count as a personal item, carry-on or are exclusions to the rule.

Inside Your Luggage and 3-1-1

Pack liquids and gels in your checked baggage. However, there are specific rules created by the Transportation Security Administration (TSA). You are permitted to carry on "1 quart-size, clear plastic, zip-top bag that holds 3 ounces or smaller containers of liquid or gels." There is a limit of one bag per traveler. Exceptions are made for medications, breast milk and baby formula, but these items must be declared to security officers at a checkpoint (TSA Travel Tips).

Check With Your Airline

Always check with the airline before packing to determine carry-on guidelines pertaining to the number of items you are allowed to carry and the maximum size of the items. There are some situations where an airline may require most or all bags to be checked, especially if there are limitations on available space during certain flight situations.