You’ve chosen the nursery furniture, painted the walls, and stuffed baby’s drawers with adorable layette pieces. Now it’s time to choose the perfect crib mattress. There are a number of things to think about as you do, and one of the most important is the crib mattress size.
In this article, we’ll walk through everything you need to know about choosing the right mattress size for your crib so your little one can stay safe while sleeping.
Table of contents
- Choosing the right crib mattress size
- Beyond crib mattress size: Additional features to look for
- Safe sleep tips
Key Takeaways
Choosing the right crib mattress size
Your baby is going to sleep in their crib a lot, so it’s important to get a mattress that’s sized just right. This isn’t a matter of style but, rather, safety.
If the mattress is too small, your baby could get stuck in the gap between the mattress and the crib side. It’s also a suffocation risk.
We know that sounds scary, but it’s not hard to find the right fit. Basically, the correct mattress size is dependent on the crib you purchased. So what crib mattress size will be right for your crib? Let’s start with your crib and take a look at the choices.
Crib type: Standard, mini, bassinet, or custom?
The first step in figuring out your crib mattress is knowing which model crib you have: Choices range from standard, mini, and bassinet to custom-shaped cribs. Let’s take a look.
Standard Crib
When researching your nursery options, you probably see many references to a “standard-sized crib,” but may wonder what this means. The Consumer Product Safety Commission (CPSC) deems a standard crib to be one with dimensions of 52 ⅜ inches by 28 inches, with ⅝ inch leeway on either side.
Standard cribs are the most common type of crib, and they come in a host of different colors, materials, and styles, ranging from traditional to uber modern.
Standard cribs are built to last from infancy through the toddler years, with many of them coming with or offering a separately purchasable toddler conversion kit. A standard crib adjusts as baby grows: The mattress starts at an upper position when the child is an infant, and then is lowered as they get bigger.
Some standard cribs offer even more convertibility. Certain 3-in-1, 4-in-1, and even 8-in-1 convertible cribs include the pieces to configure to full-size cribs and toddler beds as well as other sleep spaces like bassinets, mini cribs, and junior beds.
For instance, Newton’s Nest 4-in-1 Convertible Crib begins as a bassinet and then can be configured as a crib, toddler bed, and junior bed.
A convertible standard crib can be a great solution for someone who wants extra flexibility as to where they place the crib at various stages of baby’s growth. Often, parents will build it as a bassinet at the beginning, transition to a mini crib, and later rebuild it into a full-size crib when the baby is a little older.
Mini Crib
A mini crib is a popular choice for those with limited space. Smaller than a standard-sized crib, mini cribs can typically be used from infancy to two years old.
These are considered a half-step between a bassinet and a full-size crib. Because they don’t take as much space as a full-size crib, they fit better in your room during those first six months when the baby is supposed to room-share. Many find them preferable to short-lived bassinets.
Mini cribs are also a great option for grandma’s house, especially a model that folds down.
Shaped and custom-sized cribs
Shaped and custom-sized cribs are basically non-standard; in essence, any size but 52 ⅜ inches by 28 inches (give or take ⅝ inches on either side). These could be round or oval, square or rectangular, or bigger or smaller than a standard full-size crib.
Shaped and custom-sized cribs are more unique, often chosen on account of their style, though they can also have practical appeal. The smooth, flowing edges of an oval crib, for instance, can not only look lovely but can also optimize nursery space and be even safer, thanks to no sharp corners.
However, if you choose a custom-shaped crib, you’re more limited in options for your mattress and sheets.
Bassinet
A bassinet is the smallest version of a crib, typically only used for the first few months of a baby’s life. These are small, so they can fit easily next to your bed as you room share, making bonding and feeding convenient.
It’s important to know that a baby can only sleep in a bassinet until they are able to push up on their hands or they’re showing interest in rolling over (this typically happens between two and six months). There are some models that offer a lower level, offering extended use, however.
Now that you’ve gotten the lay of the land when it comes to cribs, it should be simple to find the right mattress to fit. So without further ado: let’s move to mattresses.
Crib mattress size: Standard
The most common mattress size is the standard mattress, which is built for a standard-size crib. Even though cribs may differ by wood, finish, and overall style, most models in the U.S. are standard-sized.
Dimensions
According to the Consumer Product Safety Improvement Act of 2008 (CPSIA), standard-sized crib mattresses that fit standard-sized cribs are 27¼ inches by 51⅝ inches.
Tips for selecting the right-sized standard crib mattress
As we said earlier, if your crib is standard-sized, you’ll need a standard-sized crib mattress. However, as crib safety is so important, it’s a good idea to perform a two-finger test just to confirm that you got it right before putting the baby down for their first nap.
Just slip two fingers in the gap between the mattress and the side of the crib. If they are snug, your fit is good. If the gap is larger than that, it’s not the right crib mattress size for the crib.
Another note: if you choose a convertible standard crib, then you’ll need several mattresses for the various configurations. The full-size standard crib configuration will require a standard-sized mattress, but other configurations will require the purchase of additional mattresses.
Crib mattress size: Mini
Dimensions
There is no government-regulated “standard” mini crib size; however, many mini crib manufacturers make their cribs to fit a 24-inch by 38-inch mattress.
Tips for selecting the right mini crib mattress
While you can likely purchase most mini crib mattresses and expect them to fit your mini crib, you’ll still want to double-check the fit because some mini cribs are narrower than others.
Mini crib mattresses are also available in different depths, so be sure to research the dimensions before making a decision.
Crib mattress size: Shaped or custom-sized
Dimensions
There are no standard specifications or government regulations for shaped or custom crib mattresses. Shaped and custom cribs vary in size, and most will likely either come with a mattress or a perfectly sized mattress will be available to purchase separately from the manufacturer.
Tips for selecting the right-shaped mattress
If you have a specially shaped crib, the same rule applies for the mattress: not too big and not too small.
If your shaped crib does not come with a mattress, you’ll want to use a tape measure to determine the appropriate size and then choose a mattress that fits snugly inside your crib without too much room around the edges.
Crib mattress size: Bassinet
Dimensions
Like the shaped crib mattresses, there isn’t a standard for bassinet mattresses. Generally, the purchase of a bassinet will include a mattress that’s just right.
Crib mattress compatibility
As you see, in most cases, your crib will either need a standard-sized mattress, or the manufacturer of the crib will make a specially-sized mattress that fits the crib perfectly.
Keep in mind that mattress size regulation is a matter of U.S. law. That means if your chosen crib is from abroad, that country’s “standard” and the U.S. “standard” may not be the same.
Beyond crib mattress size: Additional features to look for
As you begin to explore the world of crib mattresses, you’ll realize that crib mattress size is not the only factor that differentiates one mattress from another. You’ll need to keep a few other factors in mind.
Firmness
First of all, crib mattresses should be firm. While your older child might appreciate a soft and cozy bed, when it comes to your infant, the firmer the mattress the better. Soft mattresses can increase the safety risks for young babies.
It’s important to note, however, that “firm” does not necessarily mean hard. Traditional crib mattresses are rock-hard because, in order to prevent a baby's head from sinking in and to avoid suffocation risk, they are encased in non-breathable plastic.
By making the Newton mattress ultra-breathable, we were able to make it much more comfortable as well, while helping reduce the risk of suffocation*.
To be sure you have a firm crib mattress, push down on it and see if it immediately springs back into place when you take your hand away.
*Based on independent testing
Breathability
Secondly, consider going with a breathable crib mattress. This is important because non-breathable mattresses may increase the risk of suffocation for young babies.
However, you can put yourself at ease with a breathable mattress, like Newton’s Crib Mattress, which allows air to flow freely for optimal breathability and temperature regulation while your little one sleeps.
Newton’s Crib Mattress is made with our Wovenaire® technology and zipped into a comfortable, washable, and breathable mattress cover.
In fact, you can get the most out of your breathable mattress by using Newton’s Waterproof Crib Mattress Pad and skipping the sheet. The mattress pad is durable, comfortable for your little one, and machine-washable. It’s as easy as that!
Non-toxic and allergen-free materials
As your baby spends lots of time on a crib mattress, the materials used must be as safe as possible.
Fire retardants
All mattresses have to abide by strict flammability regulations, which often involve the use of chemicals. However, some mattresses meet those standards with natural materials rather than chemicals.
At Newton, we take a chemical-free approach to safety. We use a layer of viscose material, made of reconstituted wood pulp, instead of chemicals. The viscose material is sewn into the cover or a separate, inner encasement is placed under the cover.
We’re also mindful of common allergens and make sure we don’t include irritants like foam, latex, springs, or glue in our mattresses. Instead, Newton Crib Mattresses are made of safe, food-grade material.
GREENGUARD Gold certification
Another thing to look for when shopping for a crib mattress is the GREENGUARD Gold certification. Our mattresses meet these strict requirements, signifying that the mattress exceeds the highest industry safety standards.
Cleaning
Now we get to practical matters: cleaning. When choosing a mattress, you want to find one that’s easy to clean and maintain.
The Newton Crib Mattress is completely washable from cover to core. Say “goodbye” to dirt, dust, and allergens, and “hello” to sleep!
Weight
You don’t want to have to go to the gym just to lift your mattress. When your baby grows, you’re going to have to lower the mattress, which means it’s a little more tricky (and requires a little more muscle) to pull out the mattress and remove the crib sheet when it’s laundry day.
A lighter mattress will make this task easy-breezy. Our crib mattresses range from 11 to 14 pounds, which is considered quite light.
Home trial
Although we can sing the praises of the Newton Crib Mattress all day long, the best thing to do is to try it. We offer a 100-night home trial so your baby can get some zzzs on the mattress in the comfort of their own crib.
Safe sleep tips
We can’t write an article about crib mattresses without touching on safe sleep guidelines. Here are a few things to keep in mind as you put your little one to bed in their crib.
Always put baby to bed on their back.
When it’s time to turn in for a nap or for the night, the only safe way to put a baby to sleep is on their back. This helps to keep their airways open and significantly reduces the chances of overheating and suffocation.
Only let baby sleep in a crib, travel crib, or bassinet.
There are only three safe places for a baby to sleep: a sleep-safe bassinet, crib, and travel crib. If your baby happens to nod off in their car seat, in a bouncer, rocker, or swing, or anywhere else, as soon as you notice, pick them up and place them on their back in the crib.
Keep the crib bare.
Pillows and stuffed animals are cute, but they don’t belong in the crib. When your baby’s in the crib, there should be nothing inside but the mattress, the fitted sheet, and your baby.
Place the crib away from the window, cords, and heaters.
Crib placement in a room is important. According to the American Academy of Pediatrics (AAP), your crib should be at least three to four feet away from the window to reduce fall risks, drafts, and direct sunlight that could cause overheating.
Cords are a strangulation hazard, and heating vents can pose burn hazards and overheating.
Never bed-share.
Although it may be tempting to let baby sleep in your bed, don’t do it. Adult beds are not designed for babies and are dangerous due to too-soft mattresses, blankets, and pillows, which could cause suffocation or entrapment.
Do room-share
Room-sharing, on the other hand, is highly encouraged. When sharing a room, you’re able to bond more with your baby, as well as respond to their needs.
Keep your home smoke-free.
Your little one’s lungs and immune system are developing rapidly, and being exposed to smoke can increase their risk of respiratory infections like pneumonia and bronchitis.
Optimize the nursery for sleep.
This is more a tip about comfort, but it’s key to keep in mind: When it’s naptime, be sure to keep the nursery cool, dark, and quiet. Set the thermostat to 68 to 72 degrees Fahrenheit, and turn out the lights. If the sun still peeks through, consider investing in blackout shades.
When baby’s sleeping, ensure that the whole house quiets down. (Resist the urge to vacuum outside the door, or mow the lawn under the window!) If you are worried you may disturb your little one, try a white noise machine in their room that will drown out outside sounds.
Lastly, if it’s dry in your house, a humidifier might be a good idea as well. Use a cool-mist humidifier and aim for 30-50% humidity.
Sleep tight, baby!
Now you understand how important crib mattress size is to your baby’s safety and how to be sure you’re choosing the right mattress for your crib.
As you prepare for your baby’s arrival, if your crib is standard-sized, check one thing off your list and put your mind at ease by choosing a Newton Crib Mattress designed with your baby’s health, safety, and comfort in mind.
And, as we mentioned above, every mattress made by Newton is ultra-breathable, washable, and recyclable.
With a little knowledge and the tips we’ve listed here, you can have a pretty, functional crib and crib mattress that are comfortable enough for baby to rest well and safe enough to put your mind at ease.
Frequently asked questions
When should I replace my crib mattress?
Replace your crib mattress if you notice that it’s sagging, has tears in the cover, or is no longer firm. Generally, your crib mattress should last five to seven years; however, if it has had heavy use, it may need to be replaced sooner.
Are toddler bed mattresses the same size as crib mattresses?
Yes. Toddler mattresses are exactly the same size as crib mattresses, measuring about 27¼ inches by 51⅝ inches. The main difference is the firmness. Whereas crib mattresses must be extra firm to be safe, toddler mattresses can be a bit cushier.
Many crib mattresses offer “dual sides” with a firmer side for infants and a softer side for toddlers.
Are European crib mattresses the same size as U.S. crib mattresses?
No. European crib mattresses typically measure 27 ½ inches by 47.2 inches or 27 ½ inches by 55 inches, while U.S. crib mattresses measure about 27¼ inches by 51⅝ inches. This means European mattresses are sometimes shorter and sometimes longer than U.S. mattresses.
As such, you cannot use a European mattress or fitted sheets in a crib manufactured to U.S. standards and vice versa.
