Hospital Bed Mattress sizes can vary from 30 inches wide by 80 inches long, 30 inches wide by 85 inches long, 36 inches wide by 80 inches long, 36 inches wide by 75 inches long and 36 inches wide by 84 inches long. Another manufacturer may dream up even another size. These are pretty standard Hospital bed measurements. Hospital Mattress depths can vary from just a few inches to 6" or more. Many times, actual hospital mattress dimensions will vary by one or two inches, usually smaller.