In the US, the standard size of a crib mattress is 27.5 x 52 inches (70 x 132cm). In the UK, there are two standard sizes for cot mattresses, namely, standard UK cot bed mattress size is 70cm x ...

Every mattress we tested was the legal size—at least 27¼ inches by 51⅝ inches, and no more than 6 inches thick. This size ensures a snug fit in a standard-size crib. Safe crib mattresses keep ...

After all, a standard twin is just 38 inches wide, compared to the 54 inches of a full mattress, the next size up—affording ... now transitioning from their crib and into their first big kid ...