A Guide to the Standard Crib Mattress Size

What You Need to Know About Mattress Size, Length, Depth and More

Baby smiling in cot.
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Shopping for the right crib and mattress is an important first step in ensuring the safety of your newborn—yet purchasing a so-called "standard" crib mattress size can be confusing. The reason: There's no real "standard," even though the size and thickness for all crib mattress is regulated by the Federal government. The law states that the minimum size must be 27 1/4” x 51 5/8” and not thicker than 6 inches.

What You'll Find When Mattress Shopping...

Still, there can be a slight variation in width, length and depth among crib mattress. So before heading to the store, make sure to have the exact measurements of your crib.

Width and length:In both the U.S. and Canada, crib mattress size may range between 27 5/8" to 28 5/8" wide and 51 3/4" to 53" in length.

Depth: The depth of the crib mattress can vary even more—a fact that can be quite frustrating for new parents trying to find the best option for their new bundle of joy. Coil crib mattresses tend to be on the thicker side—between 5 to 6"—whereas foam crib mattresses are more on the order of 4 to 6".

Firmness: Keep in mind that a firm mattress is preferred over a soft mattresses. In fact, the firmer the better. Soft sleeping surfaces create a suffocation hazard for infants and increase the risk of SIDS—the leading cause of death in infants in the United States, according to the Centers for Disease Control and Prevention.

Put it to the test: Press on the mattress in the center and at the edges. Does it snap back readily? You don't want it to conform to the shape of your baby's head. 

Fit: It's also important to focus on whether the crib mattress is centered on the platform and fits snugly in the crib frame. A good rule of thumb: If you can squeeze more than two fingers between the side of the mattress and the crib frame, the mattress is too small and could lead to suffocation or entrapment.

How Much You Can Expect to Spend

While you don't want to cut corners when it comes to buying a crib mattress, you also don't have to blow your entire nursery budget. According to Consumer Reports, a good quality mattress can cost anywhere from $90 to $200.

Compare prices on crib mattresses

Where to Go From Here?

As a new parent, there's so many questions and so much to learn! Now that you know a bit about shopping for the right fitting crib mattress, you might find these other articles helpful:
Are Crib Bumper Pads Safe?
Should I Buy a Used Crib?
SIDS: Reducing the Risk in Your Nursery
Newborn Sleep Norms: What's Realistic, What's Not?

Sources: Centers for Disease Control and Prevention, Consumer Reports.

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