Crib Safety Standards Explained

A crib is where a baby spends more unsupervised hours than anywhere else, so it is worth knowing that it is one of the most tightly regulated products in your home. Every crib sold new in the United States must meet mandatory federal safety standards enforced by the Consumer Product Safety Commission (CPSC), and the tougher modern rules have been in force since 2011. The upshot is reassuring: a new full-size crib from a legitimate retailer already clears a high structural bar before it reaches you. The catch is that older cribs, hand-me-downs, and safe-sleep habits are not automatically covered by that bar—so this guide explains what the standards actually require, why each rule exists, and how to judge a crib you did not buy new.

We are not a testing lab—we do not lab-test cribs. This guide is built from CPSC crib-safety standards and AAP/CPSC safe-sleep guidance plus manufacturer instructions, the same foundation behind our methodology. None of it is medical advice; for questions about your baby's sleep, your pediatrician comes first.

The structural rules a crib must meet

The standards focus on the two things that hurt babies in cribs: entrapment and suffocation. That is why the rules read the way they do. None of them are cosmetic; each one traces back to a specific way babies have been hurt in cribs, which is why the standard is so precise about spacing, gaps, and protruding parts.

• Drop-side cribs are banned.Traditional drop-side rail cribs—the kind with a side that slides down—were prohibited because the moving rail could detach or create a gap, and those failures were linked to entrapment and suffocation deaths. A safe modern crib has four fixed sides.
• Slats must be no more than 2 3/8 inches apart. That is roughly the width of a soda can. Any wider and a baby could slip their body through or trap their head between the slats, so this spacing is a hard limit.
• No missing, loose, cracked, or broken slats or hardware. The whole structure only works if it is intact. A single cracked slat or a loose bolt can turn into a gap or a collapse.
• Corner posts should not stick up,because a raised post is a snag point where a baby's clothing can catch—a strangulation hazard. Posts should be flush with the panel.
• No decorative cutouts in the headboard or footboard, which can trap a head or a limb.

The mattress has to fit snugly

A correctly built crib can still be unsafe with the wrong mattress. The mattress must fit snugly inside the frame—the standard is no more than about two fingersof space between the mattress and the crib side. A larger gap is a genuine entrapment hazard: a baby can roll into the space between the mattress and the frame and be unable to get out. When you buy a mattress, match it to the crib and check that two-finger rule with the mattress pushed to one side; if you can fit more than two fingers in the gap, the mattress is too small. The fit matters even more once the baby can move—a gap you might overlook in a still newborn becomes a place a rolling or wriggling baby can wedge into—so recheck it if you change mattresses or add a waterproof pad, which should be thin and sit flat under the fitted sheet.

Safe sleep inside the crib: a bare mattress

The crib can pass every structural rule and still be set up unsafely, because what goes in it matters just as much. The AAP and CPSC are consistent here: a baby should sleep on a firm, flat mattress with a fitted sheet and nothing else. No bumpers, no pillows, no blankets, no soft bedding, no stuffed animals—these are suffocation risks. Put the baby down on their back to sleep. And note that padded crib bumpers are banned under the federal Safe Sleep for Babies Act, so even though you may still see them pictured in older nurseries, they should not be in the crib. Our safe-sleep guide walks through the full picture head to toe.

Older and used cribs: check before you trust

The standards protect new cribs, not old ones, so a hand-me-down needs a careful look. Do notuse a crib that is broken, modified, missing parts, recalled, or very old—and a drop-side crib is out no matter its condition. Before you set one up, check for recallsthe same way you would for any used baby gear, confirm every slat and every piece of hardware is present and sound, and verify the mattress still fits snugly. Never try to make an old or incomplete crib work with substitute hardware from the hardware store or parts from a different crib; the structure is engineered as a single unit, and a mismatched bolt or bracket is exactly the kind of weakness the standard exists to prevent. If a crib is missing its instructions or its original hardware, or you cannot confirm it meets the current standard, the safer move is to pass on it. A crib is not the place to gamble on "probably fine."

As the baby grows, and what certifications mean

Two more things round out crib safety. First, lower the mattressas the baby grows and can push up, sit, and eventually stand—a mattress left high is one a standing baby can topple over. And stop using the crib once the child can climb out, or when they reach about 35 inches tall, whichever comes first; at that point a toddler bed is safer. Second, on certifications: you may see GREENGUARD Goldon some cribs and mattresses. That is a low-chemical-emissions certification about indoor air quality—a genuine nice-to-have if it matters to you, but not a structural safety standard and not a substitute for the CPSC requirements above. Every new crib already has to meet the safety standard; GREENGUARD is an extra, separate label.

The bottom line

A safe crib is one that meets the modern federal standard: four fixed sides with no banned drop-side, slats no more than 2 3/8 inches apart, no raised corner posts or decorative cutouts, intact slats and hardware, and a mattress that fits with no more than two fingers to spare. Inside it, keep the surface firm and flat with a fitted sheet only, put the baby down on their back, and keep bumpers and soft bedding out entirely. Buy new when you can, check any older crib carefully against these points, lower the mattress as the baby grows, and move to a toddler bed once they can climb out. When a crib cannot clearly pass this list, the safer answer is not to use it. For choosing one to buy, see our guide on how to choose a crib.