Guide to Crib Mattress Height | When Should You Raise Your Baby Mattress?

One of the major features of your baby's crib is the ability for the crib mattress height to be adjusted. There are multiple reasons why the height should be adjusted down, and adjusted up (mainly it'll be adjusted down as your baby grows). 

Parents are often faced with many questions as to when and why they need to adjust the height - and our guide to crib mattress height should help clear up any potential questions. 

Crib Mattress Height - Is it Safe?

Before we start, however, it is important to go over some of the safety considerations. According to this study by Pediatrics, children can be injured in many different ways by their cribs or bassinets.

The determined that around over 180,000 children younger than the age of 2 (in an 18 year period) were treated in the emergency room for injuries related to:

  • Cribs
  • Playpens
  • Bassinets

There were over 12 injuries per 10,000 children. Unfortunately, the vast majority of those injuries involved the crib (83.2%), with falling from the crib rails being the largest chunk of those injuries. This means it is extra important you review the safety guidelines. 

Safety Regulations on the Crib Mattress Heightbaby climbs out the crib because the mattress height is too high

According to this study - you should measure at least 26 inches between the the baby's crib mattress and the top of your crib rail. This is from the very top of the crib mattress - which can easily be 5.5 - 6 inches thick depending on the brand you have selected. 

The main goal of the 26 inches is to create an “escape-resistant” crib safety environment that is effective even if the baby is in the standing position. What they discovered in the study is that once the side rail to mattress difference reached 26 inches - there was a significant decrease in the frequency of children climbing over the crib rails.

So if you measure more than this between your current mattress and side rail then you might want to lower the mattress setting.


When Should I Change the Mattress Height?

This depends on your situation overall, but there are some guidelines we can use from the American Academy of Pediatrics to point us in the right direction. What you’ll find below is that you’ll usually start at the baby crib's highest level before moving down to the lowest as your baby grows and becomes more mobile.

Our breakdown is as below:

Highest Setting (Start Here)


Under 5 Months

Use Only if Baby is Immobile


Middle Settings


6 - 8 Months

Use as Soon as Baby is Mobile

Use Only if Baby Cannot Stand with Assistance


Lowest Setting


8+ Months (Varies)

Use As Soon as Baby can Pull to a Standing Position


Toddler Bed


Your Baby is 35 Inches in Height or More


Highest Level

Select the highest level when your baby is under 5 months - it is very likely this is the safest choice at the highest setting. Your baby at this stage is, for the most part, immobile and not likely to do any climbing. What we found is that the higher crib mattress level will make lifting your baby easier placing less stress on our backs to frequently place the baby and pick them up. Additionally - it will make it easier to place your hand below the baby’s neck to ensure that you’re providing the most support for their head. 

Middle Level

It is recommended to lower the crib mattress level in the middle height as soon as the baby can sit up by themselves and be more mobile on their hands and knees. Now, the exact time your child is able to sit up unassisted varies from baby to baby - but you can expect them to do this when they're 6 to 8 months old (sometimes a bit earlier).

The idea is that as soon as they’re able to sit up, place their hands and knees on the ground, and roll about - it is time to lower the mattress. 

One thing to keep in mind that your baby will soon start to stand with assistance - this can be scary in the middle crib mattress setting as they might very well be able to reach the top of the side rail! You might want to adjust the baby's crib mattress levels further.

Cribs that have an additional middle setting (they have 4 adjustable positions) for the crib mattress gives you a little wiggle room to adjust as your baby develops between laying down and being on their hands and knees. We recommend erring on the side of caution, however, and move to the lowest setting as soon as they can stand assistance.

Lowest Level

Use this crib mattress support level as soon as they’re able to stand with assistance or pull themselves to a standing position. This can happen between 8 - 12 months. The lowest level will ensure the 26 inch requirement to reduce the chance of injury. 

When to Transition to a Toddler Bed?

It is recommended that once your baby reaches around 35 inches in height- you should make the transition to a toddler bed. This does mean you can also change the mattress, as the regular baby mattress might be a bit too firm for your toddler to sleep in. Thankfully, most modern cribs are designed to convert into a toddler bed as your baby grows. 


Additional Considerations

Balance Between Your Comfort & Crib Safety

Some parents might think to just place the crib mattress support at the lowest setting to “be extra safe.” This actually may be a bad thing. The reason being is that you might find yourself leaning over and straining your body to pick up your newborn off the mattress - which can result in mishandling and possibly even dropping the newborn as you are attempting to get them out. 

There is a balance point between the comfort of the parent and the physical safety of the child. You will be handling the baby - a lot - and it is important that you make the crib's mattress as accessible and easy to use for you without compromising the child. Part of being a modern parent is to know when too much is too much. 

Shorter parents

Shorter parents will have a tougher time dealing with the mattress height - especially at the lowest setting. While raising the crib mattress height will make it easier in some ways - you will want to avoid compromising too much on the safety of the child. 

Instead - considering buying a crib for shorter parents. These cribs have a low overall height, 36 inches tall at the highest, so it is more accommodating for the typical height where a shorter mom might bend at the waist. 

huge tip for parents please baby proof your windows and make them safe header image

Anticipate “What If My Baby Manages to Climb Out?”

The thought of our baby falling out of the crib and injuring themselves is horrifying. Hopefully, by following these recommendations on your crib's mattress heights we can minimize the chance of our child from climbing out over the crib rails. You should especially begin to think about these things as soon as your child can pull themselves to a standing position. 

A modern parent should think ahead. IF your child does crawl out and fall - will they at least fall in a relatively safe place? It is likely this will happen when no one is watching (because we all will get distracted just a little). 

One thing to consider is the placement of the crib - if it is next to a window they could feasibly fall out of it - especially if you keep your windows open. Below is a short list of objects I’d be wary of around the house. 

  • Windows
  • Corners of Hard Furniture
  • Hard Floors

Should I elevate or angle my crib mattress?

We’ve read about some parents recommending that you set one side of the mattress support levels to one height - and then the other side to another height so the mattress can slant. We don’t recommend this. Instead, you’ll want to place objects UNDER the mattress to help create the slant. The angle you’d want to achieve is 30 degrees - which is about 6 inch difference from front to back. 

Supposedly the incline is to help with gastroesophageal reflux disease or congestion (source), which can disrupt baby sleep. Keep in mind that you don’t want to “simulate” an elevated surface with towels, pillows, crib bumpers, or blankets as those can actually suffocate your baby. It is better to either work these items under the mattress. Nonetheless, you shouldn’t do this without approval from your pediatrician.

In general, you should review any material by the American Academy of Pediatrics to maximize the safety of your baby and the baby crib.

If you have already touched base with your pediatrician, then review the assembly instructions for your particular crib to determine if they have feature to angle the crib mattress.

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