Hospital bed mattresses come in slightly different size dimensions than regular beds. The dimensions range from 30 inches by 80 inches for the smaller beds to upwards of 36 inches by 84 inches for the largest beds. In addition to the different dimensions, adjustable hospital beds require mattresses designed to handle the stresses of movement and being bent nearly in half. Since all beds can be slightly different you should carefully measure the bed by hand before buying a mattress.
Make sure that the hospital bed is in the flat starting position. Most hospital beds have motors that allow them to bend and tilt; the bed must be flat to get an accurate measurement.
Start with the tip of the measuring tape flush against the inside edge of the foot board. Stretch the measuring tape until the tape touches the inside edge of the head of the bed. This number is the length of the mattress.
Place the tip of the measuring tape just inside the edge of one side of the bed. Stretch the tape across the centre to the inside edge of the other side of the bed. The number that lines up with the edge of the other side is the width of the mattress.
Go to the next smallest size of mattress if your measurements are in between sizes. You do not want the mattress hanging over the edges. Verify that the mattress is designed for hospital beds as most spring and coil mattresses will not work in an adjustable hospital bed due to their lack of flexibility.