when to lower crib

When to Lower Your Baby’s Crib Mattress

Written by: Alyssa Larsen



Time to read 9 min

One thing all parents have in common is an inherent concern for the safety of their children. When it comes to your little one, everything from what they eat to where they sleep comes with learning how to make it safe for them. This includes your baby’s crib and the height of the crib mattress.


As your baby gets older and starts to hit new milestones, it’s important to know when and how to adjust their crib mattress height to keep them sleeping safely and comfortably.

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When Should I Lower My Baby’s Crib Mattress?

Your baby is growing and learning every day. You blink your eyes and all of a sudden your newborn has become a rolling, crawling baby on the move. Every new milestone is a reason to celebrate! It’s also the right time to consider whether you need to lower the crib mattress to keep your baby safe.


During your baby’s first year, he or she will quickly become stronger and more mobile. When your little one hits these milestones, it’s time to check the crib height setting and lower the crib mattress:

  • Pushing up and sitting up on their own is one of the earlier signs that the crib mattress needs to be lowered. Chances are, you’ll have the crib mattress at the highest setting before this point and you’ll need to lower it to a middle setting.


  • Once your baby starts to pull up on the side of the crib to reach a standing position, the crib mattress should be moved to the lowest setting possible.


  • After your baby masters standing in their bed, they might start trying to climb out of the crib. Sometimes standing and climbing happen in quick succession and while your crib mattress should be as low as it can go, it might also be time to start thinking about a toddler bed.


  • If your baby hits 36 inches or taller regardless of where they are with their mobility, it’s safest to lower the crib mattress down to the bottom setting.

Crib Safety Tips

The American Academy of Pediatrics (AAP) provides safety guidelines to help you create a safe sleep space for your baby. The AAP recommends:

  • Room sharing, not bed-sharing, for at least the first six months to easily attend to your baby’s needs.


  • Babies up to one year old should sleep on their backs on a firm, flat surface, like a crib or bassinet.


  • Baby’s sleep space should be free from pillows, blankets, and soft toys to avoid suffocation and decrease the risk of sudden infant death syndrome (SIDS).

When it comes to choosing a crib, new parents should follow the safety standards set by the Consumer Product Safety Commission (CPSC). The CPSC recommends a crib with no more than 2-⅜ inches between slats so your baby’s head and body cannot fit through.


The crib should be assembled properly according to the manufacturer's instructions with no missing or damaged pieces or hardware. It’s essential to be aware of these safety guidelines if you’re using a vintage or hand-me-down crib.

Crib Setting Recommendations

The height of your baby’s crib mattress will be determined by several different factors. Your baby’s mobility and body length make the biggest impact in lowering the crib mattress. Age alone isn’t a reason to make a change, but when your baby hits milestones—that commonly occur at certain ages—should be your main focus.


Typical milestones and ages that will impact your crib mattress setting may look like this:

Lower baby crib


For the first three months of a baby’s life, they’re mostly immobile on their own. Your little one is safe to sleep in a bassinet or in the crib at the highest mattress setting. Either of these options will make it easier for you to pick them up and lay them down each time they need to sleep.

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Rolling Over

Around four months old, your baby may begin to roll over during tummy time. This first change in mobility is when you’ll want to move your baby from the bassinet and into the crib if you haven’t done so already. A baby who can roll over is safe at the highest crib setting since they aren’t up above the crib rail.

Pushing Up on Hands and Knees

At about six months old, babies may start to push up onto their hands and knees as they prepare to crawl. The middle setting for the crib mattress is best at this point to avoid your baby being higher than the crib rail. Some babies will belly crawl before they make it to this point and it can be an indication that they’re close to pushing up on their hands and knees.

Pulling Up to Stand

Around nine months old, your little one may start to use the bars of the crib side rails to stand up in their bed. Moving the mattress to the lowest setting now will keep your baby from tipping over the side of the crib while they’re standing.


Between 18 months to three years old, your baby may figure out how to climb up on the crib rails to get out of—or into—their bed. Once this happens there’s no going back. It’s no longer safe for your little one to sleep in their crib. You can move the crib mattress out of the crib and onto the floor until you can replace the crib with a toddler or big kid bed.

How to Safely Lower the Crib Mattress

The time for a lower crib mattress will come sooner than you think. Plan ahead by learning how your crib works and what tools you’ll need when the time comes. All cribs are different so, always refer to the instruction manual or assembly guide of your specific crib before lowering the crib mattress.


As a general guide here are a few universal steps you can expect:

1. Choose your height

It helps to identify the height your mattress is currently set at and what level you want to lower it to before you start moving pieces around. Some cribs may simply have two mattress height settings—high and low, while others may offer more.


The Crib has three height settings to provide just the right balance of safety for your growing baby and ease for parents and caregivers to comfortably reach in and care for their baby.

2. Remove the mattress

Take the mattress out of the bed completely and set it to the side. This can be a great time to throw the crib sheet and mattress pad in the wash if you haven’t done so in a while.

3. Adjust the height

Unscrew one end panel of the crib from the side rails for access to the mattress support plataform. Lower the support platform to the desired height setting, realign the end panel, and reinsert the screws. Repeat this process at the opposite end of the bed. 

4. Return the mattress

Cover the mattress with a fresh mattress pad and fitted sheet before setting it back into place in the crib.


The Lullaby Earth Breeze Air Crib Mattress is a non-toxic and waterproof option for your baby’s bed. It’s easy to keep this crib mattress clean since it comes with a breathable cover that can be removed for washing.


Make sure the mattress is firmly settled down onto the support platform before laying your baby down in the crib.

When to Transition from a Crib to a Toddler Bed

Switching your child’s sleep spot from a crib to a toddler bed is a big change. Timing the move just right can make the adjustment a little easier for your little one.


Generally, it’s best to keep your toddler sleeping in the crib as long as possible. Here are some signs that it’s time to move your toddler out of the crib:

They’re 36 inches tall

By the time your child is three feet tall, they’re at a height that’s no longer safe for the crib. Once the side rails are at your toddler’s chest level while standing in bed, there’s a risk of them easily climbing out or toppling over the side of the crib.

Your child is between 18 months and three years old

This may seem like a wide range, but more important than age, moving out of the crib depends on your child’s development and personality. Some toddlers are taller than others and may need to leave the crib sooner. While other kids might still be at a safe height for the crib and have no interest in trying to climb out—sleep sacks can help restrict the ability to climb—and it’s fine to use the crib a little longer.

There’s a baby sibling coming soon

Sometimes it’s necessary to move your young toddler out of the crib if you’ll need it for a newborn. Consider buying a second crib for the new baby if your toddler could still benefit from sleeping in the crib for a while longer. If two cribs aren’t an option, make sure you give your toddler a few months of practice in a new bed to adjust before their baby sibling is born.

They’ve asked for a “big kid bed"

Safety isn’t the only reason to make the transition to a new bed. Maybe your toddler is showing interest in a “big bed.” It’s common for young kids with older siblings to want a bed like their older brother or sister or to be like their parents. When it’s your child’s idea to move to a new bed, there’s a better chance that the transition will be smoother.

What’s the Difference Between a Toddler Bed and a Kid’s Bed?

When deciding to move your child out of the crib, you might compare a toddler bed and a kid’s bed to find the best choice for your toddler’s room. There are some key components to each style of bed that can help you decide.

Toddler Bed

The toddler bed is designed for children 18 months to four years old. It’s a smaller bed that still fits the crib mattress and sometimes just a few adjustments are needed to set up your toddler bed if you purchased a convertible crib. Toddler beds are low to the ground and equipped with safety rails on both sides. These beds are great for an early transition since they usually feature themes and colors that are exciting for young toddlers and easy for them to get in and out of on their own.

Kid’s Bed

A kid’s bed can come in various sizes, though they typically fit a twin-size mattress. This type of bed works well for children of all ages and can last for many more years than a smaller toddler bed. Since a kid’s bed is typically higher off the ground, your toddler may need help getting in and out of the bed, and side rails may be an additional purchase.


The Kids Bed from Nurture& is made with soft, rounded edges making it safe and comfortable for even the youngest “big kids.” With so many customizable options like color combos, safety rails, and trundle storage, you can truly create the perfect bed for your toddler’s room.

Your baby’s safety and comfort are the top priorities when it comes to their sleep. Lowering the crib mattress as your little one grows and meets milestones will help you maintain the best sleep environment through each new stage of life. And when the time comes, you’ll be prepared to transition your toddler out of the crib and into their first “big kid bed.”


Set up your nursery with a bed that will keep up with your growing baby, like The Crib. You can also check out The Kids Bed when you’re ready to turn your baby’s room into a toddler’s room. The modern furniture and baby essentials you’ll find at Nurture& are always created from premium, non-toxic materials made for parents, by parents.

Alyssa Larsen

Alyssa Larsen

Alyssa Larsen is a stay-at-home mom with a passion for writing. Before starting her career as a freelance writer, Alyssa devoted all of her time to her family and raising her young children. The evolution of her motherhood journey and parenting experience inspires her work. She strives to always tell a story that is helpful and relatable to the person reading it. Alyssa lives in Ohio with her husband and four hilarious kids.