Crib Mattress Buying Guide

From crib mattress size to safety and quality, our handy Buying Guide gives you everything you need to know on how to buy a crib mattress!

Smiling baby sitting in her crib mattress with a blanket and stuffed animals.

Babies can spend up to 18 hours per day sleeping, a crib mattress is one of the most important purchases when preparing for your new arrival. So what to look for in a crib mattress? We’ve broken down the basics in our Crib Mattress Buying Guide.


Buying a crib is an exciting part of your journey into parenthood – and one that many parents-to-be tackle before purchasing a crib mattress. All crib mattresses are designed to fit inside USA-standard full size cribs and toddler beds, so it’s important to measure the inside dimensions of your crib to ensure that it meets these safety standards.

  •  The inside of your crib should measure between 27 3/8 to 28 5/8 inches wide and between 51 ¾ and 53 inches long.
  •  Mattresses are designed to be slightly smaller than these standard dimensions, to be sure, use your tape measure to check that there is no more than a 1 ¼” gap between the mattress and crib.

crib mattress laying inside crib with callouts showing proper fitting and sizing.


The three main types of crib mattress categories include classic/traditional, natural, and innovative/new technology.


Sealy Baby Firm Rest Crib Mattress

These crib mattresses offer the key things Moms and Dads look for:

  • Firmness through the use of durable steel coils, border wire, and other core upgrades
  • Cushioning support that is firm enough for infants and comfortable enough for toddlers to create better sleep
  • A cover with an easy-clean waterproof surface to keep liquids, odors, and germs from clinging to the mattress.

Explore Sealy Baby Classic Collection Crib Mattresses


Families appreciate natural and organic materials in a crib mattress because they are gentler for both baby and the planet. The inventive use of some of nature’s best materials—such as organic cotton, soybean foam, soybean cool gel, and plastic-free cotton covers—create luxurious sleeping environments for babies. Additionally, using natural, renewable oils in foams helps to reduce dependency on drilling for crude oil.

Explore Sealy Baby Natural Collection Crib Mattresses


Some of the best aspects of nature & science combine to create inventive crib mattress designs that work to offer varying types of comfort & cleanliness for baby.

Some examples of these technologies include:

  • Cool gel
  • Sensory coils
  • Airflow-designed cores

Explore Sealy Baby Innovative Collection Crib Mattresses


Within all three categories, there are two main core types: an innerspring coil mattress or a foam core mattress. We break down the primary differences between the two below.

Innerspring coil mattresses are highly durable and offer optimal resiliency and posture support. Steel springs are heat tempered which allows them to gently move under a child’s weight to support them appropriately. Features to look for include:

  • Interwoven steel coils
  • A high coil count to create a firmer mattress
  • Border wire that runs around the perimeter to ensure extra support from edge to edge

Solid foam blocks for their baby’s crib are lightweight to lift and make changing sheets easier. Two-stage foam crib mattresses will use a softer material on the toddler side, like a cool gel foam or memory foam. Features to look for include:

image of a crib mattress and GreenGuard Gold Certification Logo


We know how important keeping your baby safe is, and want you to know that ALL crib mattresses sold in the USA must meet rigorous safety standards before being approved for sale. Sealy Baby proudly keeps the highest standard of Safety & Quality testing for all of our products.

In addition to the state and federally mandated standards, the main crib mattress certification to look for is a GREENGUARD® GOLD Certified crib mattress. GREENGUARD® GOLD measures the air quality and chemical emissions of a crib mattress. To meet these strict certification standards, an independent laboratory must verify there are not hazardous chemicals that pose a risk to infants and toddlers in the crib mattress or its components. All of our Sealy Baby crib mattresses meet the GREENGUARD GOLD certification.