How Thick Should A Child Mattress Be?

How thick should a child mattress be? - Header Image

Key Points

  • Most children's mattresses have thicknesses between 13 and 20 centimetres.
  • Mattresses come in firm and plush varieties.
  • Various mattress types and materials can impact price, comfort, and durability.
  • Your child's sleeping position should be considered when choosing a mattress.

Just like almost every other aspect of parenting, choosing a child's mattress isn't as simple as it might appear to be. In addition to asking yourself how thick should a child's mattress be, you also need to consider the mattress size, firmness, type, and other factors.

How thick should a child mattress be? The most suitable child mattresses are designed with a thickness between 12cm and 20cm or 5in to 8in. Mattresses below this range are likely to be uncomfortable, and going beyond this range would not provide any additional comfort and likely become awkward to fit in all bed frames for example bunk beds.

A Guide To Standard Mattress Thicknesses

To answer the question of how thick should a child's mattress be, it's helpful to start with an overview of standard mattress thicknesses.

  • Low profile mattresses are those between 5 and 13 centimetres. These are typically only found in foldaway spare beds and baby cots. Most adults and even some children would be uncomfortable sleeping on a low profile mattress.
  • Slim mattresses are those between 13 and 20 centimetres. Slim mattresses make it easy to get in and out of bed while providing more support than low profile mattresses, making them the perfect mattress thickness for most children's beds, as well as for people with disabilities or conditions that limit mobility.
  • Standard mattresses are those between 20 and 30 centimetres. This thickness is most common in queen and king bed sizes.
  • Medium mattresses are those between 30 and 50 centimetres and are typically more expensive than standard mattresses, but allow for extra comfort and support.
  • Thick mattresses are those 50 centimetres or thicker. An uncommon mattress variety, thick mattresses are heavy, unable to be compressed, and therefore rather difficult to move.

Choosing The Right Mattress Size For Your Child

The mattress size you choose for your child will directly depend on the size of their bed, which will come down to space considerations.

It is vitally important that you choose a mattress specifically made to suit your child's bed size.

A double mattress on a queen size bed, for example, introduces a very real risk of the child becoming trapped in the gap between the side of the mattress and the side of the bed.

While most children sleep in a single bed, there is no reason why your child can't have a larger bed if you have the room for it.

Choosing Mattress Firmness

Mattresses generally come in two varieties of firmness: firm and plush. Directly impacting on support and contouring, mattress firmness nevertheless comes down to personal preference.

In general, children who tend to sleep on their side prefer plush mattresses to accommodate their shoulders and hips, while children who sleep on their stomach or back tend to feel more comfortable with a firmer mattress.

The best way to find out which firmness best suits your child is to try both out in person. If your child isn't able to test the mattresses themselves, see which feels most comfortable for you.

Plush Mattresses

Plush mattresses are softer and have a pillow-top feel, providing thick cushioning.

Firm Mattresses

Firm mattresses are often preferred by children first transitioning from a cot as they are more similar to the thin, firm mattresses usually used in cots. Stomach and back sleepers also often feel more comfortable on a firm mattress to stop their midsection from sinking into the mattress during sleep.

Choosing Mattress Type

Different mattress types make use of a variety of materials and technologies to provide a comfortable and supportive sleeping experience.

Latex Mattresses

While natural latex is derived from rubber trees, several types of synthetic latexes have been designed in recent years. Latex tends to provide a "weightless" feel and is known for its durability and comfort.

Innerspring Mattresses

Often considered one of the best value mattress materials, innerspring mattresses contain a layer of coils covered by layers of foam or other materials. A traditional mattress type, innerspring mattresses are long-lasting and offer good value for money.

Foam and Memory Foam Mattresses

Foam mattresses typically contain polyfoam, memory foam, or a combination of both. A hypoallergenic choice, foam is designed to contour to your child's curves, providing a supportive sleeping experience. Foam mattresses are typically described as mattresses that are slept "in" rather than "on."

Individual Coil Mattresses

Individual coil mattresses are similar to innerspring mattresses but constructed so that each coil is contained within its own pocket. Individual coil mattresses are a newer technology and higher-quality mattress than their cheaper innerspring mattress counterparts.

Hybrid Mattresses

Hybrid mattresses can combine any number of the different mattress materials described above. Designed to provide the best of both worlds, hybrid mattresses still need to be tested along with other mattress types to find the best fit for your child.

Other Factors To Consider When Choosing Your Child's Mattress

When choosing a mattress for your child, asking yourself how thick should a child's mattress be is just one of the important considerations you'll need to make. Read on for other factors to keep in mind when selecting your child's mattress.


Mattress prices can vary considerably, making price an important factor to consider. When choosing a mattress, ensure you're aware of the price of each product before testing each one for comfort and size.

Preferred Sleeping Position

Is your child primarily a side sleeper, stomach sleeper, or back sleeper? Their go-to sleeping position can have a big effect on the relative comfortability of a mattress. Side sleepers can benefit from a plusher mattress which will absorb the weight of their hips and shoulders, while front and back sleepers are usually more comfortable with a firmer mattress that provides additional support for the midsection.


How long would you like the mattress to last? As discussed, some mattress constructions are more durable and longer-lasting than others. If you plan to keep your child's bed for many years, passing it down to younger children or using it in a spare room, consider a mattress less prone to deterioration and sagging.


Some mattresses are inherently noisier than others. You may have memories of sleeping in a particularly creaky bed in a motel or at a relative's house. While new mattresses are not often noisy, some children are such light sleepers that the slightest noise will disturb or even wake them. Test a mattress by lying on it and rolling around, paying careful attention to any noise given off.

Safety Rails

Safety rails are a must for any child when first transitioning from a cot to a bed. Children tend to move around considerably while asleep, and safety rails will prevent falls that could scare or even injure your child. The thicker the mattress, the more the height of the safety rail is correspondingly lowered. For this reason, thicker mattresses are not recommended for children sleeping with safety rails.

Your initial quest to choose a mattress for your child had you wondering how thick should a child's mattress be, but now you know there are plenty of other factors that are just as important to consider, including the mattress size, firmness, and type. By keeping the above tips and factors in mind, you can choose the mattress that will best suit your child's individual needs.