Crib Mattress Size – Detailed Guide
Crib mattresses are available not just in different sizes but also in different shapes and firmness. Regardless of the construction material and design, any crib produced in North America will fit a crib mattress because they size between 51-53 inches long and 27-29 inches wide.
But merely looking at a crib mattress will not be enough to determine the dimensions, so we have put together this detailed guide to tell you everything you need to know about crib mattresses before getting one for your baby.

Beautiful crib mattress
Crib Mattress Sizes
Crib mattresses generally come in three dimensions, and they include:
Standard Crib Mattress
The standard or regular-sized crib mattress is the most common size for baby cribs. A standard crib mattress usually measures about 6 inches in thickness, 27 inches in width, and 51 inches in length.
A standard mattress will fit into a standard-sized crib, even though there may be a little variation in sizes.
Mini Crib Mattress
Mini crib mattresses are smaller in size than standard crib mattresses. While the size of standard crib mattresses is regulated by relevant agencies, mini crib mattresses are not regulated. The typical mini crib mattress measures about 24 inches in width and 38 inches in length.
A mini crib mattress is supposed to fit perfectly into a mini crib, but you should double-check before buying because some mini cribs are smaller than others. You might also want to consider the depth of a mini crib before buying.
Shaped Crib Mattress
When it comes to shaped crib mattresses, there is no specific dimension or government regulations. Shaped cribs are available in different sizes and may come with a customized mattress.
When selecting a shaped crib for your baby, ensure you know the right measurement of the mattress so it is not too big or too small. If your shaped crib comes without a mattress, you can use a tape measure to know the dimensions of the crib and then select a mattress that perfectly fits the crib.
Types of Crib Mattresses
There are several types of crib mattresses in the market, as you will see below. The one you should opt for is a matter of personal preference than anything else.
Innerspring Mattresses
An Innerspring crib mattress is fitted with several steel coils to provide resilience and stability. For comfort, this type of crib mattress is padded with foam, cotton, or polyester. The higher the number of steel coils embedded in an innerspring crib mattress, the stronger the crib mattress.
High-end innerspring mattresses are equipped with metal rods around the edges to provide additional stability. This variant of innerspring crib mattresses weighs and costs more, but it also lasts longer.
Foam Crib Mattresses
A foam crib mattress is constructed with polyurethane, which is a lightweight foam resin. Not only is this type of crib mattress durable and portable, but it is also the cheapest crib mattress out there.
While foam crib mattresses are generally lightweight, you should go for one with higher density or firmness. You can test the firmness of a foam crib mattress by squeezing it and observing its reaction. The firmer a foam mattress, the harder it is to squeeze.
Before getting a foam crib mattress, check if it is resilient by pressing it down with your hands and observing the time it takes to regain its original shape. The faster the crib mattress regains its original shape, the more resilient it is.
Double-sided Crib Mattresses
This is a multifunctional crib mattress that is appropriate for both infants and toddlers. The firmer section is for infants, while the softer section is for toddlers who have not outgrown a crib mattress.
This type of crib mattress is long-lasting, stable, and comfortable. And so, while it is a bit more expensive than the other types of mattresses, consider it a cost-effective investment.
What to Consider When Getting a Crib Mattress
Size is not the only factor to consider when getting a crib mattress. Here are other factors to keep in mind when getting a crib mattress for your baby:
Firmness
Whether you are getting a crib for your infant or toddler, ensure the crib is firm. In fact, the firmer the crib mattress, the better for your baby. When you hear the word “hear,” do not just think of “hard’. Also, think of soft and cozy.
A firm crib mattress will stop your baby’s head from pressing into the mattress and possibly causing suffocation. To know if a crib mattress is firm enough for your baby, press it down with both hands, then remove your hands and watch how fast it springs back to its original shape.
Breathability
If a crib mattress is not breathable, your infant might suffocate while sleeping. A breathable crib mattress allows air circulation and temperature regulation, which are required for a good night’s sleep.
High-end breathable crib mattresses come with a mattress pad, so you do not have to get a bedsheet. When getting a crib mattress, ensure you go for the one labeled as “100% Breathable”.
Materials
Besides inspecting the firmness and breathability status of a crib mattress, you also have to inspect the materials used in constructing the mattress. If you are really big on comfort and stability, ensure the crib mattress you opt for is made with steel coils and soft foam.
For breathability, firmness, and safety, the crib mattress has to be constructed with upcycled cotton denim, natural coconut noir, and natural latex. When it comes to health concerns, it does not matter if a crib mattress is made of natural, organic, or chemical materials, as there is no evidence to suggest otherwise.
Fit
Regardless of the size or type of crib mattress you opt for, ensure it fits perfectly. It would be great if you knew the dimensions of your crib before buying a mattress. Use a tape measure to determine the dimensions so you do not buy a crib mattress that does not fit.
Waterproof
You need a waterproof crib mattress for your baby. Most waterproof crib mattresses are constructed with polyethylene or vinyl surfaces. This makes them also able to resist mold. However, if you have already gotten a crib mattress made of fabric, you can get a waterproof cover to protect the crib mattress.
Safety Guidelines for Using Crib Mattresses
When using a crib mattress, keep the following safety guidelines in mind:
Nothing Should Be in the Crib
While pillows, toys, and bumpers might seem indispensable, do not keep them in your baby’s crib to avoid suffocation.
Babies Should Sleep on their Backs
Pediatricians recommend that the best sleeping position for babies is on their backs. So, to prevent sudden infant death syndrome (SIDS), which affects babies under one year, your baby’s back should be touching the crib mattress.
Seek Expert Advice When Using a Double-sided Mattress
Although most parents switch to the toddler bedside when their babies hit one year, it is not the best decision, especially if the baby is yet to start walking. If you are using a double-sided crib mattress, it is best to consult a pediatrician to know when to switch bedsides.
Do Not Use Second-hand Mattress
While second-hand crib mattresses are obviously cheaper, it is best to avoid them because of the possibility that they may be infested with mold and bacteria. If you are using a crib mattress for a newborn baby that the older sibling used, ensure that the waterproof seal is still intact.
Related
