Daybed Size Bed Dimensions are usually twin size bed dimensions of 39 inches by 75 inches. There is a full or double daybed size of 54 inches by 75 inches but these are a bit rare. These are Daybed size mattress measurements. Daybed Size Mattress depths can vary from just a few inches to 14" or more. Generally, you want to keep a daybed mattress lower profile or lower height so you don't hide the fancy backboard. Many times, actual daybed mattress dimensions will vary by one or two inches, usually smaller.
Metric to U.S. Conversion
For measuring purposes, the exact conversion is as follows: