Baby crib mattress size

Baby Crib Mattress Size | How to choose a crib mattress of the right size?

How to choose the right crib mattress size?

So, you have the best and most beautiful crib for your baby. But what about a crib mattress? Picking the right size is one of the most important features you have to consider when buying a baby crib mattress. Only a crib mattress with the fitting dimensions will provide a safe sleeping environment for your little bundle of joy.

A crib mattress must fit snuggly into the crib! There should be as little space as possible between the mattress’s edge and the crib’s frame! Wider gaps increase the risk of injuries and suffocation! So, choose a standard-size crib mattress for a full-size crib, a crib mattress with smaller dimensions for a mini crib, and a right portable crib mattress for a Pack ‘N Play or travel crib.

1. Are the dimensions of all standard-size mattresses the same?

Yes, as the name “standard size crib mattresses” tells by itself, are their dimensions standardized. A very small size deviation is allowed, but in general, we can say that the size of all full-size crib mattresses is the same.

2. Is there a one crib mattress size for mini cribs too?

No! You have to be a little more careful when choosing a mini crib mattress. Check up thoroughly if the mattress dimensions correspond to the interior size of your crib to fit snuggly into it.

The right crib mattress size is not the only thing you have to consider when buying a crib mattress! We have made a crib mattress buying guide, where you can find everything you need to know when buying a crib mattress.

Does your crib mattress fit into your crib?

If you already have a crib mattress, you can check if it fits perfectly into the crib. A two-finger home fitting test couldn’t be easier and quicker. I recommend doing it with any crib mattress, new or used one! Better be safe than sorry!

Baby Crib Mattress home fitting t

This way, you can further check if you have chosen the right crib mattress size and make sure you didn’t buy the wrong one. If there is a visible gap between the mattress’s edge and crib’s frame, place your fingers there. You shouldn’t be able to fit more than two fingers in the gap!

The size of a standard (full-size) crib mattress

Among cribs of different sizes, is choosing a mattress for the full-size crib the easiest task. Interior measurements of full-size, or should I say standard-size cribs, are defined by the law. The same goes for standard-size crib mattresses!

Such regulation enables that all standard crib mattresses fit into all full-size cribs. However, the government can control only the sale of new cribs and crib mattresses! So, if you decide on a second-hand crib or crib mattress, don’t forget about the home fitting test before the use!

The law defines:

  • A standard crib is a baby crib with the following measurements: 52 3⁄8 ± 5⁄8 inches in length by 28 ± 5⁄8 inches in width.
  • A standard size crib mattress is a baby crib mattress with the following measurements: at least 27 1/4 inches by 51 5/8 inches and no more than 6 inches thick.
Standard Crib Mattress Size

Although there are usually no problems with fitting, there is a bit of wiggle room within the regulations. Why? Because the provisions allow a slight deviation. 

If the internal size of your crib is the maximum allowed, and you choose a standard crib mattress with the minimum allowable dimensions, you may end up with a gap. That is unlikely, but still, carefully check the dimensions of both, and do not put the baby in crib before you don’t make the fitting test!

RELATED: Best crib mattresses

What size is a mini crib mattress?

The government does not regulate the size of mini crib mattresses and mini cribs as they do for standard models. Any crib with smaller dimensions from a full-size crib is defined as a mini crib. As a result, the interior dimensions of mini cribs can vary a lot.

Manufacturers cannot make crib mattresses in so many different sizes. But there is an unwritten rule, to which more or less all mattress’s and mini crib’s manufacturers stick.

The size of most mini cribs on the market is 38 inches long by 24 inches wide, where the most mini crib mattresses correspond to those measurements.

Mini Crib Mattress Size

Before buying, make sure that the size of the mini crib mattress matches the internal dimensions of your mini crib. And make a home fitting test before the use!

Portable crib mattress size

To tell you what size crib mattress you need, I would have to know what portable crib you have.

Did you know that the group of portable cribs include travel cribs, Pack ‘N Plays, and even wooden or iron cribs on wheels? They are also available in both sizes. What I am trying to say is, this group is extremely versatile, where each type needs a different crib mattress.

Mini and full-size portable cribs:

For full-size and mini portable cribs on wheels, apply the rules described above! Use a standard-size crib mattress in a full-size portable crib and a mini crib mattress in a mini crib!

Interior dimensions of full-size portable cribs are standardized! So, all full-size portable cribs take standard-size crib mattresses.

When choosing a mattress for a mini portable crib, you have to consider the same rules as for other mini cribs.

Crib mattress size for travel crib and Pack ‘N Play:

Pack ‘N Plays and travel cribs come with a travel mattress. You can not use a regular crib mattress in them! It is too thick and not safe for the baby!

You should use only the included traveling mattress or contact the manufacturer about the replacement!

Be extra careful when buying a portable crib mattress for a travel crib or Pack ‘N Play! It is hard to find a snuggle-fitting model, and most of them are also too thick.

These cribs have mesh sides that do not offer enough resistance. They bend easily, causing the risk of falling from a thicker mattress. So, even if the mattress fits perfectly, it is not a suitable choice if it is too thick!

The baby can become stuck between the crib side and the mattress edge. That may induce injuries or even cause suffocation.

Most travel cribs and Pack ‘N Plays take the portable crib mattress, which is up to 3 inches thick, but as I said, check by the manufacturer first!

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