
Crib mattress sizes vary from standard to mini and custom shapes. Knowing the right size for your baby’s crib isn’t just a detail — it’s vital in creating a safe bed for your little one.
A well-fitted mattress keeps your baby comfortable and minimizes risks like gaps, which can be a serious safety concern. Understanding crib mattress sizes helped me make the best choice for my family. With the right fit, I felt confident that my baby had the perfect place to sleep, allowing me to get a great night’s rest.

Standard Crib Mattress Size
A standard crib mattress is made to fit full-size cribs. According to the Consumer Product Safety Commission (CPSC), it must be 28 inches wide by 52 inches long.
However, some variation is allowed as long as the mattress measures at least 27 1/4 by 51 1/4 inches long without exceeding the 28 by 52 inches limit. These dimensions help ensure a snug, safe fit in the crib, keeping your baby safe.
Mini Crib Mattress Size
The mini crib mattress is a smaller option, commonly measuring about 24 inches wide and 38 inches long. This type of crib is a great choice if you have limited space in your home or live in an apartment.
Unlike standard mattresses, mini crib dimensions aren’t regulated, so they can vary slightly from one brand to another. This means it’s important to double-check your mini crib measurements to ensure a snug, safe fit without any gaps around the edges.
Shaped Crib Mattress Size

Shaped crib mattresses are designed for cribs that aren’t the typical rectangle. They can be circular, oval, or hexagonal. These cribs usually come with a custom-fit mattress, so you won’t need to worry about finding one that fits initially. However, if you ever need a replacement, it can be tricky to find the exact size again.
What to Consider When Buying a Crib Mattress
When I bought my first crib and mattress, I had no idea how important it was to pick the right one. A few key details can make all the difference in creating a safe, comfortable sleep space for your little one.
Firmness
One of the most important things to look for in a crib mattress is firmness. A safe mattress for your child should be firm and supportive. A soft mattress can increase the risk of suffocation and is associated with sudden infant death syndrome (SIDS).
To check the firmness of the mattress, press your hand on it. If it’s firm enough, your hand won’t sink in, and the surface will quickly return to its original shape.
Breathability
A breathable crib mattress encourages airflow, helping your baby stay cool and comfortable, especially during warmer months. By allowing heat and moisture to escape, a breathable mattress prevents warmth from building up and keeps the mattress dry, reducing the risk of overheating.
Thickness
A crib mattress should be between 4 and 6 inches thick. This range will give your baby the right support without raising the mattress too high. This helps protect your child, who may be learning to stand and might tumble.
Durability
The lifespan of a crib mattress can range from 3 to 8 years, depending on its quality and materials. If you purchased a used crib with a used mattress, remember to check its firmness to ensure it’s safe for your little one.
FAQs About Crib Mattresses
How long can an infant sleep on a crib mattress?
An infant can usually sleep on a crib mattress until around 3 years old but it will depend on the child’s height and comfort needs.
How much does a crib mattress cost?
The cost of a crib mattress can range from $26 to $1065, depending on factors like materials and brand.
Are toddler mattresses the same size as standard crib mattresses?
Yes, toddler mattresses are the same size as standard crib mattresses, measuring 28 inches wide by 52 inches long.
More About Cribs and Bassinets
Knowing crib mattress sizes is more than just a shopping detail, it’s also an important safety feature. A snug fit reduces gaps that could lead to suffocation. I was lucky that my crib came with a perfectly fitted mattress, but if yours doesn’t or you need a replacement, remember that size matters.
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