The best way to make sure you are within the requirements for size is to assume the safe maximum size of twenty two inches by fourteen inches by nine inches. Airline regulations state that one carry on bag and one personal item is allowed by each passenger. But exactly what counts as a personal item? This is generally assumed to be a camera, a briefcase, a purse or handbag, a laptop computer in a carry bag, a small backpack or duffel bag, an umbrella, reading material, and any other item that does not exceed the size limit of thirty six inches in total dimension.



There are exemptions to this limit for coats, hats, assistive devices like canes or crutches, diaper bags, and others depending on the circumstances. If you go to board the plane and you are not within the limits concerning your carry on luggage, you may have to check your excess luggage.

International flights have different rules concerning carry on luggage, and there are weight limits concerning carry on bags on this type of flight. These flights are much stricter about enforcing the amount and weight of your carry on luggage. Sometimes the weight limit allowed on international flights is as low as eleven pounds, which is less than some empty carry on bags weigh. The size and total dimension of carry on luggage that is allowed on some international airlines may be smaller than those allowed on domestic flights.

The specific plane that you are a passenger on may have specific requirements on top of those requirements in place by the airlines. If your plane is a very small model, the weight limit per passenger will be significantly reduced, sometimes to as low as a twenty pound limit that includes checked and carry on luggage.

The formula that the Transportation Security Administration wants everyone to know and follow uses the simple formula 3-1-1. This stands for three ounces bottles or less, in one quart sized clear plastic bag with a zip top, with only one bag per passenger. There are exemptions, such as medications, formula or expressed breast milk when traveling with an infant or toddler. These exceptions do not get put into the clear bag, but they must be declared to security officials at the security check points.