An eastern king mattress is the largest standard mattress available, according to Bedding Experts. It is 76-inches wide and 80-inches long. A California king mattress is 4 inches longer, but it has 4 inches less width than an eastern king mattress.
Queen mattresses are 60-inches wide and 80-inches long, providing adequate sleeping room for two grown adults, states Bedding Experts. The extra width of the eastern king and California king mattresses permits the inclusion of small children or pets in the sleeping arrangement. Full or twin size mattresses provide adequate sleeping space for one child or adult. Special lengths can be custom ordered for taller individuals.