The safest size of baby cribs and crib mattresses is determined by the federal government. The Consumer Products Safety Commission (CPSC) requires all full-size baby crib mattresses to be at least 27 and ¼ inches in width by 51 and ¼ inches in length, with a maximum thickness of six inches. But for cribs, the standard size isn’t as simple.

The CPSC requires that full-size baby cribs have a standard width of 28 inches and a standard height of 52 and ⅜ inches, but with a “pull or minus factor” of ⅝ inches. Because of this variation, it’s important to look for the recommended mattress size listed on the crib’s box and/or assembly instructions.

All Delta Children, Serta and Beautyrest crib mattresses are compatible with all Delta Children cribs, making it easier to buy the products that are safe for your little one’s nursery.

Crib mattresses should fit very snug or moderately snug in the crib. No more than two fingers of space should exist between the side of the mattress and the crib frame. A mattress that is too small for the crib could be a suffocation and entrapment hazard.

The firmer, the better when it comes to crib mattresses. Soft surfaces can pose a suffocation hazard and increase your baby’s risk of Sudden Infant Death Syndrome (SIDS). You can test a how firm a mattress is by pressing on its center and edges. When you release pressure, it should snap back immediately.