Sleeper Sofa Bed Dimensions range from the twin sleeper sofa mattress at 36 inches wide and 72 inches long, to the full size sleeper sofa mattress at 52 inches wide and 72 inches long, to the queen size sleeper sofa mattress at 60 inches wide and 72 inches long and finally the queen XL sleeper sofa mattress at 60 inches wide and 75 inches long. These are standard sleeper sofa size bed measurements. Sleeper Sofa Mattress depths can vary from just a few inches to 6" or more. Many times, actual sleeper sofa mattress dimensions will vary by one or two inches, usually smaller.