Guest Bedroom Bed Size . While a trundle bed is integrated into a primary bed, the murphy bed is attached to the wall. A queen bed is measured at 60 inches by 80 inches. Bed Frame Wooden Mattress Foundation Twin Size Stable Bed Platform for from www.walmart.com Alternatively, you can use a queen bed to provide extra living space. It may be bigger than that but 224 square footage is a minimum. While researching what many feel is the best bed size for guests…i was amazed to find that a number of people really love two twin beds.