Do cribs come with a mattress? Here is what nobody mentions at the baby store.

You put the crib together. Stood back. Felt that small, tired satisfaction. Then looked around and realised nothing came to put in it.

Almost every crib sold today does not include a mattress. If you assumed one would be in the box, you are in very good company. Here is what you actually need to know.

Here is what is actually going on

Crib manufacturers sell mattresses separately because no single mattress fits every crib correctly, and the fit matters. Even a small gap between the mattress edge and the crib frame is a safety concern. Selling them separately means you can find one matched precisely to your crib's interior dimensions, rather than getting whatever the factory decided to bundle.

It also means the safety standards that govern cribs and the standards that govern mattresses are assessed independently. In the US, crib mattresses must comply with Consumer Product Safety Commission (CPSC) federal rules covering firmness and off-gassing limits. A bundled mattress that no one individually certified would skip that check.

So yes, you need to buy one. But the fact that you are choosing it yourself is genuinely better for your baby.

Why safe crib mattress choices matter for newborn sleep

For most of the first year, a crib mattress is where your baby spends the majority of her hours. What most pediatricians will tell you is that the surface she sleeps on is one of the few things in the safe sleep conversation you can actually control. The American Academy of Pediatrics recommends a firm, flat, non-inclined surface with no soft bedding, bumpers, or loose items in the sleep space.

A soft mattress, however comfortable it feels to the touch, does not support a baby's airway the way a firm one does. That is not a preference. It is the reason firmness is the first thing to check.

If you are also wondering what else belongs in the crib alongside the mattress, the guide on what actually belongs in the crib covers every item, from fitted sheets to sleep sacks.

How to check crib mattress firmness, fit, and certifications

You are looking for three things before anything else.

• The firmness test. Press firmly in the centre of the mattress. It should push back immediately, with no indent remaining. If it holds a dent, it is too soft.
• The fit test. Place the mattress in the crib. Run two fingers along each side between the mattress and the frame. If your fingers slide through without resistance, the gap is too large. The mattress should fit snugly with no more than a finger's width of space on any edge.
• A certification mark. GREENGUARD Gold certification means the mattress has been tested for chemical emissions and off-gassing. JPMA (Juvenile Products Manufacturers Association) certification means it has met CPSC safety standards. Either is a good sign. Both is better.

If a mattress passes those three checks, it is almost certainly a safe choice. Everything else is personal preference.

Things that actually help

Match the mattress to your specific crib

Standard crib mattresses in the US are roughly 27.25 by 51.625 inches. Most full-size cribs accept a standard mattress. But convertible cribs, mini cribs, and travel cribs all have different interior dimensions. Check your crib's instruction manual or product page for the exact interior dimensions before buying.

Choose firm over everything else

Foam and innerspring are both fine. Organic cotton and coconut coir are both fine. What is not fine is a soft, pillow-top, or memory foam surface. Memory foam moulds around pressure, which is the exact property that makes it dangerous for a baby who cannot yet reposition her head. When in doubt, go firmer.

Add one waterproof cover

A fitted, waterproof mattress cover (not a thick topper, a cover that fits like a sheet) is genuinely useful. It protects the mattress from the many liquids that will eventually find it, and it wipes clean. One cover is enough. Two, if you want one in the wash while one is on the crib.

Skip the extras

No crib bumpers, no pillows, no thick quilts, no mattress wedges, no rolled towels. A fitted sheet, a waterproof cover, and your baby. That is the full picture for the first year. For the full breakdown on how to set up a safe sleep space from day one, that guide walks through every element.

Do not reuse a mattress from another baby

It feels wasteful to buy new when a barely-used mattress is sitting in storage. But used mattresses lose firmness over time in ways that are not always visible. What most pediatricians will tell you is that a new mattress for each baby is the safest choice. If cost is a concern, a basic certified foam mattress starts well under $100.

Tonight could be the night it clicks

Willo has 12 sleep sounds built for little ones, a bedtime routine that tracks itself, and a sleep plan matched to your baby's current phase. When nothing's working at 2am, you'll be glad it's on your phone.

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Things that tend not to help

• Buying based on softness. The softer it feels in the shop, the less appropriate it is. A firm mattress is not uncomfortable for a baby. It is what her spine and airway need at this stage.
• Assuming a high price means better safety. Certification marks matter. Price does not automatically track with safety. A $60 GREENGUARD-certified foam mattress can be safer than an uncertified one that costs four times as much.
• Adding a mattress topper for comfort. Toppers add softness, which adds risk. Skip them entirely for the first two years.
• Choosing based on how it feels to you. Babies do not sleep the way adults do. A surface that feels like a board to your hand is appropriate for her.

When to stop reading articles and call your pediatrician

Most families do not need medical guidance on mattress selection. Speak to your pediatrician before making a decision if:

• Your baby has been diagnosed with or is being evaluated for a breathing or airway condition
• Your baby has reflux and a healthcare provider has suggested a sleep positioning device (these are generally not recommended and require professional guidance before use)
• You have been given conflicting advice from a specialist about your baby's sleep surface

For everything else, the firmness test, the fit test, and a certification mark will cover you.

How Willo App makes this easier

Inside Willo App, your baby's sleep space fits into her phase. From the earliest weeks through the first year, you will have phase-matched sleep guidance, a daily bedtime routine to follow, and sleep sounds for the nights that do not go to plan. Ask Willo is there at 2am when you cannot remember which side of the mattress faces up, or when you just need someone to tell you that you are doing this right.

Setting up the crib is one of those tasks that feels enormous and then, once it is done, quietly becomes part of the background. You are nearly there.