Child products are sensitive. That’s the reason, parents become over conscious about baby products. Unlike many other products, crib mattress has to meet some standards. But strictly speaking, there is no hard and fast standard. Yet the size of the crib mattress has to meet federal government prescribed dimensions.
And the Federal government dictates the minimum size must be 27 1/4” x 51 5/8” and not thicker than 6 inches. As there are a lot of security issue involved, the government has to play the role.
No matter whether you buy a mini crib, travel crib or a standard size crib, make sure it meets ASTM International & U.S. CPSC safety standards.