Crib Mattress Dimensions Guide (Sizes & Types)

One of the most important decisions parents make for their infant is choosing the right crib mattress. You want your little one to be comfortable, but you also have to consider price, value, and safety factors.

It’s no surprise that the crib mattress market offers a large range of crib mattresses from which to choose.

There is more to choosing a mattress for a baby’s crib than just the brand. You need to have the proper crib mattress dimensions to fit your baby’s crib.

Crib mattress size is regulated by the US Consumer Product Safety Commission (CPSC) as of February 15, 2022. The crib mattress dimensions Canada regulations fall into the US standard range at 28 x 51 inches, or 71 cm x 129.5 cm. Also, any crib mattress made before 1986 is considered illegal for use.

Therefore, before you make a purchasing decision about crib mattresses, this guide will address things you need to know and the options available to you.

The first part of this guide will discuss and compare crib mattress dimensions for standard baby cribs, mini cribs, toddler beds, and twin beds.

Crib Mattress Dimensions

Is there a standard size for cribs?

There is an acceptable and regulated range for standard-sized crib mattresses. The range for a crib mattress in inches is between 27 ¼ x 51 ⅝ inches and 28 x 53 inches in the United States. The same is true for the convertible crib mattress size and the toddler mattress size.

Therefore, crib mattress sizes in Canada regulations and the United States regulations are well matched.

Are all crib mattresses standard size?

The regulations instituted by the United States and Canada also cover other factors besides crib mattress dimensions, though the size range plays a role in the safety of crib mattresses.

Not all crib mattress dimensions meet the standard size, however, due to the new regulations about crib mattress dimensions, there is a range that manufacturers have to meet, which was mentioned in the above paragraph.

Safety regulations include the following:

  • Crib mattress firmness to prevent suffocation hazards that are affiliated with crib mattresses that are too soft.
  • Improper crib mattress fit can cause infant/baby entrapment.
  • Neglect by after-market mattresses for non-full-size crib mattress dimensions that also cause an entrapment hazard.
  • Broken exposed springs and coils in crib mattresses are prone to cause lacerations.
  • Suffocation and Sudden Infant Death Syndrome (SIDS) risks related to soft bedding, gap entrapment issues, and infant positioning.

The newest regulations address these issues to ensure that all crib mattress dimensions fit properly, are at the proper height (no more than 6 inches), and protect infants and babies from suffocation, injury, and entrapment.

Is a crib mattress the same size as a toddler mattress?

Yes. Toddler beds and convertible cribs are designed to fit standard crib mattresses as per the aforementioned regulations set in the United States and Canada.

Most toddler beds are designed to fit the standard crib mattress dimensions of 27 by 52 inches, which is similar to the full-sized crib mattress. Mini crib mattresses are not compatible with toddler beds.

If you have a mini crib, the mattress will not match the toddler bed mattress size. You will need either to get a full-size crib mattress or choose a convertible crib with a standard-size crib mattress.

Observe the table below that describes the standards of crib mattress dimensions and a comparison to other mattress sizes.

Crib mattress size chart and comparisons:

Standard Crib MattressMini Crib MattressConvertible Crib MattressToddler MattressTwin Mattress
28 x 52 x 5 inches Canada crib mattress size in cm: 71 cm x 129.5 cm24 x 38 x 3 inches28 x 52 x 5 inches28 x 52 x 5 inches38 x 75 inches
Range: 27 ¼ x 51 ⅝ inches to 28 x 53 inchesUnregulatedRange: 27 ¼ x 51 ⅝ inches to 28 x 53 inchesRange: 27 ¼ x 51 ⅝ inches to 28 x 53 inchesStandard
Same as a toddler mattressSmaller than a standard crib mattressSame as a standard crib mattressSame as a standard crib mattressLarger than a standard crib mattress
Range: 5 – 6 inches in heightRange: 3-4 inches in heightRange: 5 – 6 inchesRange: 5 – 6 inches in heightBetween 6 and 12 inches
Firm is betterFirm is betterFirm is betterFirm is betterFirm to medium is better

Crib Mattress vs Mini Crib Mattress

Standard cribs measure about 28 inches by 52 inches, while mini cribs measure 24 inches by 38 inches. That is a significant difference between crib mattress dimensions.

It’s advisable to get a new crib mattress according to the standard dimensions before transferring your child to a toddler bed. A mini crib mattress will not be safe.

Crib Mattress vs Toddler Mattress

Essentially, crib mattress dimensions and toddler mattress dimensions are the same. You need to check the brand and manufacturer of the mattress dimensions before making a buying decision. However, these mattress sizes shouldn’t vary from the regulated standards.

Crib Mattress vs Twin Mattress

The standard crib mattress is between 27 ¼ x 51 ⅝, while the twin size mattress is 38 x 75, making the twin bed mattress standard much larger than the standard crib mattress dimensions.

Also, the standard crib mattress height is between 5 and 6 inches, while twin beds can range from between 6 and 12 inches in height.

Your child should be able to use a toddler bed for years before needing a twin bed and mattress. Remember that a crib mattress’s thickness should be no more than 6 inches and should be firm.

Why are the crib mattress dimensions important?

One of the safety goals for babies is to prevent them from getting stuck between the crib frame and the mattress. The baby could suffer an injury or even suffocation if the mattress isn’t the right fit.

Experts recommend having less than an inch between the crib frame and the mattress when the crib mattress is pushed against one side.

Top Brands of Crib Mattresses

There are many name brands to after-market brands of crib mattresses on the market.  The following are 5 top name brands that meet the standard regulations for baby cribs.

  • Ikea crib mattress – Multiple foams or pocket spring models that fit safety and crib mattress dimension regulations in a firm and medium firm.
  • Sealy crib mattress – Baby Flex Cool with foam-covered coils, waterproof surface, GREENGUARD Gold Certified, and a lifetime warranty.
  • Saatva crib mattress -Dual-sided organic crib mattress with an accident-proof removable cover, GREENGUARD Gold Certification, nontoxic for infants to toddlers.
  • Graco crib mattress -Premium foam water resistant GREENGUARD Gold Certified crib mattress with a 6-year warranty.
  • Milliard crib mattress – CertiPUR-US Dual Comfort System with waterproof hypoallergenic foam mattress for infants to toddlers.

What is a shaped crib?

If making a buying decision about standard crib mattress dimensions isn’t enough, there are also shaped cribs and mattresses.

Oval- or circle-shaped cribs and matching mattresses meet the standard regulations and fit between the mini crib and standard crib. Shaped cribs are bigger than mini cribs but smaller than standard (full-sized) cribs.

Something to be aware of is the gap between the shaped crib and mattress needs to be as small as possible. If you can fit two fingers in the gap anywhere on a shaped crib and mattress, you need to get a different mattress.

Like mini cribs, shaped cribs aren’t regulated according to the mattress size, but they may be regulated according to other specifications such as mattress thickness, firmness, and fit.

How to Choose a Crib Mattress

To complete this crib mattress dimensions guide, we will include 5 tips for choosing the right crib mattress.

Know the Regulations

Stick to the regulated standard crib mattress dimensions mentioned in this guide, which are between 27 ¼ x 51 ⅝ inches and 28 x 53 inches in the United States and 71 cm x 129.5 cm in Canada.


A crib mattress should be solid and firm to reduce the risk of SIDS or suffocation, which occurs most often in infants under a year old. In the United States, 2,500 infant deaths occur because of SIDS.


If you choose an innerspring crib mattress, a thickness, or height of between 5 and 6 inches is recommended.

If you’re choosing a foam crib mattress, a thickness of between 4 and 6 inches is ideal.

The rule of thumb is to not exceed 6-inches in thickness. This reduces the risk of falling. Either one of these options delivers comfort, support, and safety.


Airflow is an important factor that impacts a baby’s sleep. A breathable crib mattress prevents sleep disruptions and promotes a healthy sleep cycle.

Good airflow also allows good air circulation which keeps the bed cool and the baby from overheating, which commonly awakens tots. This applies to innerspring, foam, or latex crib mattresses.

Cost and Value

Price shouldn’t be the primary concern when choosing a crib mattress, but it’s expedient for those on a budget. Most crib mattresses are affordable at $150 on average, while others may cost over $300 or under $100.

You want to get the best value for your money, which is one reason parents choose convertible beds and crib mattresses that take their child from infant to toddler stages.

Overall, make sure the crib mattress you choose is durable, comfortable, safe, and has the proper crib mattress dimensions needed via regulations.

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