A queen size mattress is 60 inches wide by 80 inches long. The height of a queen size mattress can range from 8 inches to over 14 inches. Queen size mattresses are the most commonly purchased of all sizes and are the most popular mattress size on the market. They are a good choice for couples and co-sleepers, and most bedrooms can accommodate a queen size bed. If you sleep with a partner, pet, or child, a queen size mattress should comfortably accommodate you. However, if you share your bed with more than one child or pet, a queen may not be large enough.