Measure your bag with the measuring tape. Most airlines have a size limit as well as a weight limit when it comes to carry-on baggage and baggage that you check. For most airlines, 45 inches is the maximum size for the sum of the length, height, and width of your carry-on bag. If the bag is larger than this, it does not matter how much it weighs, you will have to check it.
Pack your bag with everything that you are planning to bring.
Place the packed bag on a scale. Check the weight against the weight limits of the specific airline you will be using. Adjust the weight of your bag by removing things if it is over the limit.
