The size of a laptop case is measured in height, width and depth but also usually comes with a description of what size laptop it can hold. To measure your laptop simply use a ruler or tape measure to figure out the length from the lower left corner of the screen to the top right corner. Laptop measurements are normally expressed in inches. It is important to note that laptop measurements do not include the casing that surrounds the screen or protruding parts such as hinges or ports. Therefore it is usual for laptops to take up more space than stated. This means that a 15.6-inch laptop may require a 17-inch laptop case in order to ensure a snug and secure fit.