Choosing the Perfect Crib Mattress Size

One of the many things a baby needs is a mattress to fit the crib. Anxiety is the most common feeling around babies sleeping, but it doesn’t have to be. Following this guide to choosing the perfect mattress for your crib will ensure that your baby is as safe as can be.

A standard crib mattress’s dimensions are between 51 and 52 inches in length, 27 and 28 inches in width, and not more than 6 inches in thickness. When you press one side against the crib, there should be no more significant gap than 1 inch between the crib side and the mattress.

There are many things to look for in the size of a crib mattress. It depends on what size crib you have, what type of mattress you are looking to buy, and your budget for the bed. Let’s look at some critical aspects of a crib mattress size.

Get it Right From Day One: Picking Out the Right Crib Mattress Size

To pick the correct size of a crib mattress, you will need to measure your crib. Most standard cribs are the same and vary slightly as per regulations, but it might be best to measure and be sure, especially if you got a hand-me-down.

You will need to place the measuring band inside the crib in length and width from one corner to the next. The mattress dimensions are slightly smaller to fit into your crib. Your crib is not the standard size if the measurements are way off.

Are All Crib Mattresses The Same Size?

Suppose you are looking at a standard crib, yes. According to federal law, they are supposed to be more or less the same size. However, other crib/bed sizes might differ from the standard.

A Diagram with all Crib Mattress Sizes
An Illustration of Crib Mattress Sizes
  • Mini crib mattress – sizes at 24 inches x 38 inches. These mini cribs are perfect when you have a smaller room for the baby or the baby is sharing a room with you. They will outgrow this bed earlier by 18 months of age.
  • Standard crib mattress– sizes at 27 inches x 52 inches. Buying a standard crib will be a more brilliant buy as it will last your baby up to 3 years of age.
  • Pack N Play mattress – sizes at 26 inches x 38 inches. This is the standard size for most graco and other brands of playards. Many parents use pack n plays as portable alternatives to traditional cribs.
  • Toddler bed – A toddler’s bed uses the same mattress as a standard crib. That is why some standard cribs can convert into toddler beds.
  • Bassinet mattress – sizes at 15 to 18 inches by 30 to 33 inches. These cribs are smaller and perfect for your newborn to 6-month-old baby to sleep in your room.

There are a few different shaped and sized cribs out there. Because these are not standard, they are obligated to sell the crib with the appropriate mattress to fit. The only problem with this is that you don’t have a say in how organic, breathable, or firm the bed is.

Why Are The Dimensions Of A Crib Mattress Important?

There are a few reasons why the dimensions of a crib mattress are what they are. For the infant’s safety, the US consumer product safety commission implemented a law in 2011 to state the size a crib mattress has to be to keep the baby safe.

This mattress size ensures that the baby’s head, arm, or leg does not get stuck between the mattress and the crib’s side. The recommended height of no thicker than 6 inches ensures that the baby doesn’t climb out of the crib when bigger and correlates to the mattress’s firmness.

A too-soft mattress might hinder the baby from moving and rolling the way they want to, causing discomfort or even suffocation.

How Does The Top Brand Crib Mattresses Compare In Size

The top-selling mattresses have various sizes, materials, and, obviously, prices. The one you decide on will have to be the one you feel most comfortable buying.

MattressSize of Mattress
Milliard Hypoallergenic Baby Crib Mattress and Toddler Bed Mattress52″L x 27.5″W x 4.75″T
Dream On Me Twilight 5” 80 Coil Inner Spring Crib and Toddler Mattress52″L x 28″W x 5″T
Graco Premium Foam Crib & Toddler Mattress52″L x 27.62″W x 5″T
Newton Baby Crib Mattress and Toddler Bed52″L x 28″W x 5.5″T
Hiccapop Pack and Play Pad [Dual Sided]38″L x 26″W x 3.25″T
Dream On Me Aster 3″ Fiber Portable Crib Mattress38″L x 24″W x 3″T
Table 1. Sizes of the most popular crib mattresses

Most of the above mattresses fall into the standard size category with 52″ in length and varying between 27.5″ and 28″ in width. The average thickness is 5″, which is perfect according to the dimensions for a standard size crib mattress.

The other two, which are more suitable for a pack ‘n play, specifically state that they are not standard and only compatible with 38″ x 26″/24″ play yards.

The Top Selling Crib Mattresses Have A Lot In Common

By taking the above mattresses and comparing them, we can see a trend that people are looking for:

  • Size of the mattress – All are compatible with a standard crib and toddler bed. Play-yard mattresses are two of the above and not the same as the standard size.
  • “Greenguard Gold Certificate” – states that the product has minimal chemical emissions. A definite must-have with a baby/toddler mattress.
  • Waterproof – most mattresses are waterproof or are accompanied by a waterproof cover, making it convenient for the client and protecting the mattress to last longer.
  • Dual-sided – this is one of the features that most top-selling mattresses have. It enables the client to use the one side for the baby and turn the bed when they are entering the toddler phase.
  • Manufacture warranty – This warranty gives the client peace of mind knowing that if any problem arises with the material or quality, they can replace it without any cost.

If you want to look into the top-selling mattresses and their specs, here is an interesting article featuring some of the beds we added above, categorizing them into the best budget mattress, best convertible mattress, etc.

Bonus: What To Look For In A Crib Mattress

Apart from the size, there are a few other things to consider when buying a mattress for your crib. These will ensure your baby is safe and comfortable during their hours of sleep.

The Firmness Of Your Crib Mattress

The firmness of the mattress is essential for safety as well—the firmer the surface, the better for babies. If the bed is too soft, suffocation risks are higher, and SIDS may appear (Sudden Infants Death Syndrome).

Another option is to buy a double-sided mattress. These mattresses are firm on one side and softer on the other side. When you convert the bed into a toddler’s bed, you can turn the mattress to the weaker side.

The Breathability Of Your Crib Mattress

Breathability in a mattress is vital for temperature regulations as well as safety. Different materials used to manufacture the bed have additional breathability.

Spring coils regulate the temperature very well. If you are looking for a foam mattress, you might opt for a natural latex mattress, as these have a cooling effect. Parents usually want to go for an organic mattress, which is a great idea, as these are 70% to 100%  all-natural materials meaning no unwanted substances your baby might breathe in.

Rather Spend Money On A Quality Crib Mattress

Suppose you are shopping for a crib mattress; instead of going for a bargain, rather bump up your budget for this item. Cheaper mattresses may wear off over time, affecting the firmness and harming your infant.

After storing, these other mattresses might hide chemicals and fungi, even though the bed looks clean—budget for a mattress between 150$ and $300 with a certificate of 100% organic. If you opt for the standard size, this mattress can be worth the buck, as it will last your baby longer.

Add Protection To You Crib Mattress

To ensure your mattress lasts longer, purchase a mattress protector. Babies and their wet nappies are a given, and by adding a protective waterproof sheet, you can keep your mattress protected for all your kids to come.


We can conclude that when it comes to crib mattresses, size matters. A standard-size crib would be the go-to to ensure you are well off from the newborn stage to the toddler. Because these are according to specific guidelines, you won’t struggle to find the correct size for your wanted needs when it comes to the specs of the mattress.