As the name suggests, a split queen mattress is actually two mattresses divided lengthwise down the middle. Each individual mattress measures approximately 30 inches wide by 80 inches long. Split queen mattresses are primarily intended for couples who use adjustable beds. The split allows you and your partner to independently elevate or lower your own side of the bed without affecting the other side. One thing to keep in mind: though the dimensions are identical, split queen sizes for a given mattress usually cost more than standard queens.