Mattress Sizes

Twin/Twin X-Long
Twin mattresses are 38" x 75" and are a good choice for small children and toddlers transitioning from a crib to "big kid" bed. Twin X-Long mattresses are most commonly found in college dorm rooms and add an extra 5" in length.
Full/Double
Full size mattresses are the next size up, with dimensions of 53" x 75", actually 15" wider than a twin. While it’s a common misconception that full size mattresses are a good fit for couples, they’re actually better suited for individuals. Although twin mattresses are the most common pick for children, full sized mattresses work better when you want something that will grow with your child and last throughout their teenage years.
Queen
Next up are queen size mattresses, which are 60" x 80", the perfect dimensions for most standard bedrooms.  It's bigger than a full and can comfortably fit two bodies and they're also a bit more affordable than king mattresses.
King
King size mattresses offer the most space of all standard sized mattresses. They measure in at 76" x 80", making them a whole 16 inches wider than a queen. If you’re looking for something a little longer, you can opt for a California king, which measures 84" x 72". King and California king mattresses are perfect for couples, kids, and even the family pet!  They’re a good choice for putting in a master bedroom, for families and couples who like their personal space as a king size provides 30% more sleeping space than a queen.  Also, if you're a couple who likes to read or watch movies in bed, a king will give you more than enough space to do so.