A significant milestone in a child's early years is transitioning from a crib to a child's mattress. But not all parents choose the same approach: some opt to move straight from a crib to a full-sized mattress, while others use a toddler bed as an intermediate step.
In this article, Ru9 provides you with detailed information on the right children's mattress sizes for your child!
1. How to determine the best mattress size for your child
Mattresses, in general, come in various styles and sizes. When buying a mattress for your child, there are many factors to consider. Among them, determining the right size for your child's bed will depend on several factors, such as:
Your child's age
A child's age largely determines the mattress size you should purchase. As they grow physically, their needs will also change over time.
Your child's age is one of the important factors in choosing a mattress for them.
For example, young children often spend more time playing at night, so floor space is often more important than a large mattress to sprawl on. In contrast, older children spend more time lounging and sleeping soundly through the night. Therefore, a spacious mattress can become more important.
Your child's bedroom space
Room size is another decisive factor when choosing a children's mattress size, even helping to rule out certain types of mattresses. Make sure you have measured the baby's room before you start looking for a new bed and mattress. Your child might want a small double bed, but if the room is too small, that might not be the most practical mattress size!
Does your child share a room with siblings?
If sharing a room with other siblings, you may be limited by space when choosing a children's mattress size. Of course, this is where bunk beds are an excellent option, helping to maximize space.

The right mattress for your child is important.
But please note that the minimum recommended age for a child to use the top bunk is 6 years old. So, this should only be an option when one of your children has reached this age.
Read more:
- Can infants sleep on memory foam mattresses?
- Guide to choosing the correct size for single mattresses
- Summary of current popular standard mattress sizes
2. Guide to choosing a toddler mattress size
As noted above, with rapid development during ages 1-6, you may need to replace your child's bed after only a few years. Keep this in mind when budgeting for your child's bed and mattress. If you are considering buying a toddler bed, please note the following:
- Toddler beds are smaller than standard single beds. The size of a toddler bed ranges from 144 - 166cm in length and 73 - 79cm in width.
- Toddler beds require a mattress size of 70cm x 140cm, the same size as a crib mattress. So if your child is transitioning from a crib mattress, you may not need to buy a new mattress immediately.
- The thickness of a toddler mattress also needs to be less than a single mattress, because toddlers are more likely to sleep on their stomachs at night.
Many families prefer topper mattresses placed directly on the floor, convenient for children.
- Some toddler bed and mattress designs are placed directly on the floor, adopting the Montessori method which encourages independence through learning and play.
Read more: How to choose a cool mattress for infants for good heat dissipation, helping children sleep better
3. Guide to choosing a mattress size for older children
Whether you decide to go straight from a crib to a single bed, or from a toddler bed to a single bed, a single bed is the most common size for children. You can choose a single bed for your child based on the following considerations:
- The size of a standard UK single bed is typically 200 cm long, 99 cm wide and requires a single mattress size of 90 cm x 190 cm.
- The size of a standard EU single bed is 212cm long, 102cm wide and requires a single mattress size of 90cm x 200cm.
- Single beds are usually higher than toddler beds. If you are thinking of buying a single bed for a toddler, you might consider attaching a bed rail until you are sure the baby is used to being on a larger bed.
Read more:
- Should infants sleep on a bed or a mattress, which is better?
- What are the standard sizes for double mattresses and single mattresses?
- Thin mattresses, foldable, affordable, and most popular today
4. Guide to choosing a mattress size for teenagers
There will come a time when a single bed is not large enough for a teenager, but if you simply want to size up to a small double bed or double bed, here are some considerations:
Small double bed mattress size
- The size of a standard UK small double bed is approximately 198cm long, 128cm wide, and requires a standard UK small double mattress size of 120cm x 190cm.
- The size of a standard EU small double bed is 208cm long, 128cm wide, and requires a standard EU small double mattress size of 120cm x 200cm.
Double bed mattress size
- The size of a standard UK double bed is 200 cm long, 145 cm wide, and requires a standard UK double mattress size of 135 cm x 190 cm.
- The size of an EU double bed ranges from 210cm long, 148cm wide, and requires an EU double mattress size of 140cm x 200cm.
Foam topper roll-up mattresses come in many different sizes, suitable even for children.
To better visualize children's mattress sizes, you can refer to Ru9 mattresses, especially the foam topper roll-up mattress. However, is a foam mattress good for infants? With soft memory foam material, OEKO-TEX® certified safe, the Ru9 foam topper roll-up mattress allows your child to be comfortable anywhere and at any age. Diverse sizes offer maximum comfort: pleasant, convenient, safe, suitable for every family:
- Single: 120x200x5cm
- Full: 140x200x5cm
- Queen: 160x200x5cm
- King: 180x200x5cm
- Square King: 200x200x5cm
- Super King: 220x200x5cm
- XSingle: 100x200x5cm
In summary: With a suitable bed and mattress, your child will have a cozy place to sleep soundly every night. If you feel your child is old enough for a larger bed, you can certainly try to make the change, but more than anything, keep your child's safety in mind.
Related articles:
- Experience in choosing a foam mattress for babies to ensure a good night's sleep
- How to choose a good mattress for infants to create comfort and comprehensive development for your beloved baby!
- Buy now memory foam mattress in Hanoi
- Best foam mattress brand today - the top choice for a quality experience
- Mattress toppers where to buy high quality?