Changing pads differ in dimensions, with the average size being approximately 17.5 x 27.5 inches. If you have a particular spot that you are planning to keep and use your changing pad, measure the space before you buy it to ensure that it fits. If you are using your changing pad on a changing table, dresser or another elevated position and is too big, it poses a safety risk. However, you may want to ensure that your changing pad is large enough to see you through to toddlerhood.