How Should A Crib Mattress Fit

Helen Skeates
Helen Skeates
25 min read

If you want a quick response to the question of how snugly a crib mattress should fit, know that there should be zero gaps or extra room. Below, I will explain some easy strategies for achieving the best possible fit. It’s important to keep in mind that sizing a mattress, even for something as simple as a crib, can be a bit of a guessing game.

To that end, we have compiled a comprehensive baby mattress size guide for your perusal. Please read that so we can make sure you fully grasp our sizing advice.

Benefits of a Crib Mattress Pad


You can keep your crib or toddler bed’s mattress in pristine condition with the help of a mattress protector. The main thing it does is prevent nighttime mistakes like leaky messes. You may assist ensure that your baby has a healthier environment to sleep in by purchasing a mattress protector for the crib. Quilted toppers and waterproof barriers both aid in keeping liquids and stains off of the mattress.

How to Choose a Crib Mattress


Mattress pads for cribs can be washed and dried in a machine for your convenience. A crib mattress pad can be easily washed in place of the entire mattress, allowing baby to return to sleep much more quickly after an accident. In addition, having a spare mattress pad is a good idea. Comfort

Quilted crib mattress pads offer an extra layer of padding and a safe, plush surface for sleeping infants and toddlers.


Several manufacturers now offer technologically advanced mattress pads for infants’ cribs. Some crib mattress pads even repel stains and odors, making for a fresher, cleaner sleeping environment for baby, while others feature temperature-regulating fabrics that keep things nice and cool for your little one.

Natural Options

If you want to pamper your child with the gentle comfort of nature, an organic cotton top is the way to go. Cribs with a mattress pad made from natural materials can have a soft, comfortable sleeping surface that is also highly absorbent.

Everything To Know About How Should A Crib Mattress Fit

Fitting a mattress to a crib correctly is essential. Once the mattress is in place, there should be no space large enough to insert two fingers between the crib’s sides and the mattress. The risk of asphyxia or trapping can be reduced by ensuring the crib’s end panels reach below the mattress.

How Do I Know If A Crib Mattress Will Fit?

Please measure your crib’s inside length, width, and height before you go shopping for a mattress to fit your crib. Then, insert two fingers between the mattress and the crib side to conduct the two-finger test. In that case, you’ll need a bigger bed since they’ve somehow managed to squeeze through the opening. The mattress should fit the crib so snugly that putting it together is a challenge.

How High Should The Crib Mattress Be For A Newborn?

Because infants have not yet developed the motor skills to roll over or climb out of their cribs, it is still safe to place the mattress at the highest setting. In addition, putting the crib mattress at the highest setting will make it easier for you to support and lift your baby in and out of the crib. When the crib mattress rail is at its highest setting, you can use it to verify that the mattress is no more than 26 inches from the floor.

What Is The Standard Size For A Crib Mattress?

Since newborns can’t get around yet, it’s perfectly safe to put the mattress of their crib at the maximum setting while they’re still in there. In addition, if you put your baby’s crib mattress on its highest setting, you’ll have an easier time supporting and lifting your child in and out of the crib. When the crib mattress rail is at its highest setting, you can use it as a measuring stick to make sure the mattress is no more than 26 inches from the floor.

Take careful note of your crib’s measurements so you can get a mattress that fits snugly and safely within the crib. There are also cribs that aren’t the standard rectangular shape. It’s important to have the right-sized and shaped mattress for these models.

Are Crib And Toddler Mattresses The Same Size?

If you round up the extra quarter inch, a normal mattress for a crib or toddler bed measures exactly 28 by 52 inches. Since the mattress is already in good condition, many parents just place it on top of the toddler bed frame. However, you should still measure the crib mattress to ensure it will fit in the toddler bed.

However, you should keep in mind that you are using a mattress designed for use with rails. As a result, the mattress from the crib will rest closer to the floor if you put it on a toddler bed. A child may also express discomfort with the rigidity of the cot.

Are crib and bassinet mattresses the same size?

Because bassinets are smaller than cribs, the mattresses for the two will be different sizes. The standard dimensions for a bassinet mattress are 30 by 33 inches in length and 15 by 18 inches in width. Check out this resource for information on where to get a bassinet mattress.

How Do I Know If My Crib Is Too Small?

You should make sure that your crib’s inside measurements adhere to the standards set forth by the American Society for Testing and Materials (ASTM) and the federal government. The recommended dimensions for a crib to accommodate a regular mattress are 28 inches in width by 52 inches and 3 eighths in length. Once your child’s height is less than 75 percent of the crib’s side rail, it’s time to drop the crib and transition him to a bed.

The 9 Best Crib Mattresses for Babies and Toddlers

Best Overall : Newton Baby Crib Mattress and Toddler Bed

Favorite Things

  • Cooling
  • Easily maintained
  • The ability to hold its shape while still allowing air to circulate

Disliked Aspects

  • A strong plastic scent has been reported by some consumers upon opening, but this typically dissipates following a wash.

The Newton Baby Crib Mattress is the ideal option for a good night’s sleep. It has cutting-edge breath-through technology that helps prevent suffocation and the negative health effects of rebreathing carbon dioxide. This feature will help keep your infant cool and comfy all night long.

Both the detachable cover and the mattress itself may be cleaned easily. Parents may rest easy knowing their child is not exposed to any allergens while sleeping on a mattress made without foam, glue, latex, or springs. Newton Baby is an environmentally responsible brand because their products are made from recycled materials and have earned the GreenGuard Certification, ensuring minimum chemical emissions.

Parents who have purchased this mattress have expressed their appreciation for its breathable construction and cooling properties, which alleviate any concerns they may have had about their infant’s temperature while sleeping. Its safety record makes it a top choice for parents who want to give their infant the freedom to sleep on their tummy. The Newton Baby mattress is pricey, but it may be used from birth through toddlerhood with little to no modification.

Users have noted a strong plastic scent upon opening, so keep that in mind. Thankfully, this issue tends to disappear after the first wash.

Covered? : Yes | Lifetime Warranty | Dimensions: 52 x 28 x 5.5 inches | Materials: Recyclable food-grade polymer GreenGuard Gold Certification.

When Do You Drop Your Crib Mattress, Because You Don't Want Baby To Escape

Best Budget : Graco Premium Foam Crib and Toddler Mattress

Favorite Things

  • Dense and bolstering
  • Include a protective cover for your investment.
  • Excellent cost-effectiveness

Disliked Aspects

  • Preparation involves fluffing and expanding.

The Graco Premium Foam Mattress is an inexpensive option for those looking to provide their kid a safe and pleasant place to sleep without breaking the bank. This mattress has been tested for more than 10,000 chemicals and VOCs known to contaminate indoor air, and its cover may be thrown in the washing machine if it gets dirty.

Memory foam is breathable and supportive enough for newborns. This mattress may need to expand for a few hours after being removed from the box, as it was compressed for transport. After that, you have a durable and comfortable bed that will serve you well for many years.

Foam construction; 5 inch thickness; Covered? ; Yes; 6-year warranty; GreenGuard Gold and CertiPUR-US certifications; 52 by 27 by 5 inch dimensions

Best Organic : Naturepedic Organic Crib Natural Mattress

Favorite Things

  • An impermeable membrane serves as the exterior of this waterproof package.
  • Natural and harmless
  • The firmness is extreme.

Disliked Aspects

  • Possible eventual sinking

Using a Naturepedic product guarantees that your baby’s crib mattress is made entirely of organic, non-toxic ingredients. This alternative, which does away with the need for standard springs, is both portable and strong. The flammability and sustainability criteria for farming and chemical emissions are met by the breathable materials.

The firm base and reinforced edges ensure your baby stays safe all night without dipping to one side. Aside from keeping moisture out, pests and dust mites are also kept out thanks to the watertight seams. Accidents happen, but if you have a mattress that can be easily cleaned, you won’t have to stress about stains.

Best Splurge : Avocado Organic Crib Mattress

The solid base and strengthened edges ensure your baby stays safe all night without dipping to one side. Seams that are sealed to prevent water seepage also keep insects and allergens out. In the event of an accident or spill, you may easily clean your mattress with a damp cloth.

  • Your infant will be secure all night long thanks to the wide, sturdy base and high, padded sides. Insects and dust mites are kept out, and water is kept out, thanks to the waterproof seams. Easily clean up any mishaps on your mattress by wiping it down.
  • Naturally occurring and non-toxic
  • Robust and enduring

Disliked Aspects

  • Pricey considering how long it will be in use.

Choose an organic mattress, like this one from Avocado, to give your child peace of mind that they are not sleeping on chemicals or poisons. The natural latex, wool, and cotton fibers in this product create a breathable and comforting environment for your baby to sleep in.

Avocado claims to protect your child and the environment by sourcing its wool and cotton sustainably in India without the use of pesticides, herbicides, or fertilizers. Although the 28-pound mattress made from organic materials is more durable and comfortable in the long run, it also seems heavier than the alternatives on the market. The large weight and high price may put some off, but the choice’s hygienic construction and two-in-one design for infants and toddlers more than compensate for those drawbacks.

Covered? Yes, 25-year warranty, certified GreenGuard Gold, OEKO-TEX® Class 1 standard, and 52 by 28 by 6 inch dimensions.

Best Convertible : Moonlight Slumber Little Dreamer Crib Mattress

Favorite Things

  • Long-lasting quality
  • Cushioned but supportive
  • Dual-sided

Disliked Aspects

  • Thin, watertight exterior

An increasingly soft crib mattress is used as infants get older to ensure their comfort while sleeping. This Moonlight Slumber mattress has two distinct sides, so rather than buying two, you can use it throughout your child’s development. One side is made of extra-firm plant-based foam that is perfect for newborns. The second one is made of super-cuddly foam, perfect for napping babies and restless toddlers.

The medical-grade stretch knit fabric is highly durable and resistant to moisture, stains, odors, bed bugs, and allergens. This vinyl-free, antimony-free, phthalate-free, lead-free, non-irritating mattress for your infant will give you peace of mind. In case of mishaps, the waterproof case is an added bonus.

Size: 52″ x 27.5″ x 5″ Depth: 5″ Material: Medical-grade foam Cover: Yes 8-Year Warranty: No Certifications

Best Breathable : Colgate Eco Classica III Eco-Friendlier Crib Mattress

Favorite Things

  • Long-lasting
  • Waterproof
  • Environmentally-friendly

Disliked Aspects

  • Initially, some people noticed a faint chemical odor.

Your baby’s ability to breathe should not be compromised in the event that he or she rolls over to their stomach during the night, thus it is important to get a crib mattress that allows air to pass through it. High-quality, certified safe foam is used in this product, so your baby won’t have to worry about suffocation or inhaling in any allergens or toxins.

There is no need to worry about spills or leaks ruining your mattress with the dual-sided option’s built-in waterproof backing. The “eco-foam” of Colgate’s Eco Classic Mattress has been impregnated with plant oils, as the product name suggests. The indispensability of this product is ensured by its robust, lightweight, and harmless composition.

Covered? Yes | Lifetime Warranty | CertiPUR-US, GreenGuard Gold Certifications | 52 x 27.75 x 6 Inch Dimensions

Best Mini : Delta Children Serta SleepTrue Mini Crib Mattress

Favorite Things

  • Produced using waste bottle materials
  • A thicker option than the competition
  • Durable enough for newborns

Disliked Aspects

  • Disappointingly little chill

Miniature cribs need for a unique smaller mattress that nevertheless needs to meet all the safety requirements of a full-sized mattress. The Serta SleepTrue Mini Crib Mattress from Delta Children has a nontoxic build, waterproof cover, and 10-year warranty, so it meets all our requirements.

The four-inch-thick, solid fiber core is manufactured from post-consumer plastic bottles and provides maximum support for your infant. With two distinct surfaces, this mattress may be used for a long time, or at least until your child grows out of it. This lightweight option is especially convenient for traveling.

Covered? : Yes | Cover thickness: 4 in | Covered? : Yes | Covered for 10 years | GreenGuard Gold certifications Dimensions: 38 x 24 x 4 in

Best Waterproof : Sealy Baby Firm Rest Waterproof Standard Toddler & Baby Crib Mattress

Favorite Things

  • Durable
  • Affordable

Disliked Aspects

  • Making a racket under cover

A baby’s resting area must be kept clean at all times, so a waterproof mattress protector or mattress is a must. It makes it much easier to wash and clean up spills or accidents without fear of staining or damage. We recommend this option from Sealy since it has a waterproof cover that is both antimicrobial and odor-resistant, and it is bound with lock-stitching to ensure that nothing can get inside.

Find a mattress or cover for the baby’s crib that is watertight to ensure a dry and sanitary sleeping environment. It makes it much easier to wash and clean up spills or mishaps without concern of stains or damage. We recommend the Sealy option due to its lock-stitched binding and waterproof, antibacterial, and odor-resistant cover.

Best Innerspring : Kolcraft Pure Sleep Therapeutic 150 Waterproof Toddler & Baby Crib Mattress

It is essential to protect your baby’s crib mattress or use a waterproof crib mattress cover. This reduces the hassle of cleaning up after an accident or spill and eliminates the risk of stains or damage. This Sealy option is highly recommended because to its waterproof, lock-stitched cover that prevents moisture from escaping and also acts as a barrier against the growth of bacteria and the odors they can produce.

  • Hypoallergenic
  • Cleanup is a breeze
  • Waterproof

Disliked Aspects

  • The walls aren’t as robust as some alternatives.

When it comes to firmness, durability, and lifespan, nothing beats an innerspring mattress with its internal coils. Infants can’t sink to the bottom or tip to one side because to the coils. Little ones find the springiness and flexibility to be quite comfortable.

The non-removable cover of this Kolcraft mattress is both watertight and stain-resistant, making cleanup a breeze. Cover is not removable, but it is constructed of hypoallergenic, breathable fabric that is perfectly fine for your infant or child.

Cover? : Non-removable Dimensions: 51.63 x 27.25 x 5 inches Material: Foam Thickness: 5 inches Warranty: 10 years Certifications: GreenGuard Gold Size: 51.63 x 27.25 x 5 inches

What to Look For in a Crib Mattress


It would be unfortunate to order a mattress for your child’s crib just to find out that it does not fit. The typical dimensions of a crib are 28 by 52 inches. You should make sure there are no sags or wrinkles in the mattress while placing it in the crib. According to pediatric nurse practitioner Lindsay Albutt, this prevents your infant from “sinking” into the mattress or “slipping” to one side and becoming trapped. All of them, she explains, are suggestions backed by the American Academy of Pediatrics.

A standard crib mattress will not fit in a mini or portable crib. Mini crib mattresses should ideally fit within a space that is 24 inches wide by 38 inches long; this is to ensure that the crib can be properly assembled. Creating a secure and cozy nursery is the first step in ensuring a peaceful night’s sleep for your newborn.


There are many different options for crib mattresses, including those made of foam, cotton, wool, and polyester. The method by which a material is constructed may be more significant than the substance itself. Make sure the crib you buy is made from non-toxic, chemical-free materials to protect your baby’s health as they sleep. Try to find labels that say “organic,” “non-toxic,” and “hypoallergenic” when you’re out shopping. This ensures that your baby’s mattress will not cause any allergic reactions.

A mattress’s material can also have an impact on how hot or chilly it is during the night. If your infant tends to become hot easily, you may want to invest in a special mattress designed to keep them cool.


According to Albutt, SIDS can be prevented by always putting a baby to bed on his or her back on a flat, hard surface. Approximately 72 percent of the annual SUDI death toll of 3,400 is attributable to dangerous sleeping conditions, as determined by her study. It is, therefore, more crucial to take even modest precautions to keep your child safe while they sleep.

For Mommywise’s Natalie Nevares, firmness is preferable to comfort because it prevents babies from suffocating when they turn over. “If I wouldn’t want to sleep on the mattress, I don’t want my baby sleeping on it,” she says.


When looking for a crib mattress, Nevares prioritizes both firmness and breathability. Most mattresses are designed so that a baby can still breathe even if they roll onto their stomach. While some textiles are naturally more permeable than others, it’s always a good idea to look for products that tout their lightweight construction and breathability.

When shopping for a crib, avoid items with cushion tops or comfort tops, advises Elizabeth King, CEO and founder of Sleep Baby Consulting. She explains, “Baby’s face might get stuck in these squishy gaps, which can make it hard for them to breathe.”


While the materials and manufacturing processes used to make crib mattresses aren’t always essential for baby safety or comfort, they can be a selling point for some parents. A firm mattress that is Greenguard Gold Certified is what you should be looking for if you are shopping for a mattress for your kid. Certified sleep consultant Kaley Medina says the certification guarantees the mattress’s inside has low chemical emissions. This implies that both your baby and the environment will benefit from the use of safer materials.


Waterproof crib mattresses can be quickly cleaned by wiping them down or washing them in the event of an accident. In order to prevent water from penetrating, the covers of several of the items on this list are permanently stitched together. Still others feature interchangeable parts that can be cleaned and reused. Waterproof covers can be added to any of the items on this list to make maintenance a breeze.

Be aware that waterproof covers typically make a lot of noise or crinkle as you move around in them. They are usually manufactured from plastic or vinyl, neither of which are particularly conducive to a good night’s sleep. Mattresses should come with waterproof covers as standard, but if they don’t, you may want to consider getting one. Brands may claim their mattresses are organic and non-toxic, but that doesn’t mean the waterproof covering is the same. Having gone to the trouble of finding a non-toxic, organic, allergen-free mattress, you wouldn’t want to cover it with something that isn’t just as clean and safe.

Crib Mattress Fit & Dimensions | Size Guide | Sealy Baby


How do you clean a crib mattress?

Most mattresses sold for use in infant cribs are designed to be easily cleaned. Most of the items on this list may be cleaned quickly and easily by tossing them in the washing machine once a week or after any incidents. Similarly, you may prevent spills and stains from penetrating the fabric by using coverings that are waterproof and can be easily wiped clean. Prior to diving in, make sure you read the care instructions so you can be ready for any accidents that may occur.

Do crib mattresses make a difference in a child’s sleep?

Neither Medina nor Navares thinks the quality of the crib or mattress is the most important factor when it comes to your child’s rest. Even so, one good place to start is by making the nursery a secure and pleasant place for the infant. According to Medina, training a child to fall asleep without the aid of sleep associations or sleep props is the single most important thing a parent can do to help their child develop healthy sleep habits. Making sure your baby is comfortable in his or her crib and that all necessary safety measures have been taken can help immensely with this.

Even more so, as Nevares points out, “Sleep and development go hand in hand. When they start obtaining enough high-quality sleep, their growth accelerates rapidly. That’s why it’s so important to do anything you can to help your infant get a good night’s rest, including investing in a good mattress.

What do babies need to sleep?

A good, flat mattress and a fitted sheet are necessities for a baby’s crib. The sheet should be as snug as possible on the mattress to prevent suffocation in the event that the baby rolls over onto its stomach. For the safest sleep, “the mattress with the fitted sheet are the only two items that should be in your baby’s crib,” advises Medina. This means no mobiles, blankets, stuffed animals, toys, bumpers, etc. As a result, it is crucial that the few items a newborn needs in order to sleep are of the highest possible quality and safety standards.


And with that, I’ll wrap this up. As we have seen, there are specific guidelines that should be followed while purchasing a mattress for a baby’s crib. You shouldn’t be able to fit two fingers between the mattress and the side of the crib, for starters.

We hope our crib mattress size reference is useful in your search for a healthy and comfortable sleep surface for your infant. If you have any further queries, please leave a remark.

Helen Skeates

Helen Skeates

Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.