Choosing the size of your kid's bed is just as important as the unique type of bed of bed they'll be sleeping on. With a long list of sizes to go over, some new parents may feel overwhelmed. By doing a bit of research before you pull the trigger, you'll save yourself from any spending regret and feel satisfied knowing you've made a great choice for your child's development.

So let's get into the sizing itself, starting with a list of sizes and a visual guide covering our recommendations for mattress and bed sizes:

What are the best bed sizes for kids?

Beds come in a handful of different sizes, and honestly – bed sizing names are a bit confusing. The sizing of a bed is actually more about choosing the right mattress, as mattresses come with specific names attached to them.

While loft-style beds and bunk bed mattress sizing seems like it would follow a different set of rules, usually a bed's size is based on the mattress that’ll be situated on top. Regardless, finding a high quality mattress is the first step you'll need to take when considering your child's bed frame.

These names or dimensions may even change depending on where you look, but here are the most common bed and mattress sizes:

Kids’ mattress size guide from crib to Cal King with tips for bed choices , further details are provided below.

Common Mattress Sizes for Kids

Pick the right size mattress and give your kids a cozy place to rest

Crib/Toddler 52" L x 28" W

Junior 63" L x 28.5" W

Twin 75" L x 39" W

Twin XL 80" L x 39" W

Full 75" L x 54" W

Queen 80" L x 60" W

King 80" L x 76" W

Full XL 80" L x 54" W

California King 84" L x 72" W

Kid's bed sizing tips

Toddlers should sleep in their own bed when possible, even if they share your sleeping space or bedroom Taller kids and teens may prefer a longer bed, making twin XL's and Full XL's the best option for bigger kids Buying a bigger bed during early childhood years can help you save money as you'll spend less on new mattresses

Crib mattress

Dimensions: 28” x 52”

Crib mattresses are the smallest mattress sizes available, meant for toddlers and babies who still need to sleep within a safe, cozy, and protected space. You can find a few different kinds, such as a standard crib mattress or mini crib mattresses.

Junior mattress

Dimensions: 28.5” x 63”

Junior mattresses, also known as “small singles” are still pretty small, but they're a step up in size from a crib.

Twin mattress

Dimensions: 39” x 75”

The smallest of all “traditional” mattress sizes, twin and single mattresses are usually meant for kids or adults with limited space, 90% of the beds we create at Casa Kids are twins.

Twin XL mattress

Dimensions: 39” x 80”

Usually the same width as twin mattress sizes, twin XL mattresses come with a bit of extra length to accommodate taller children, teenagers, and adults without a ton of space to spare.

Full mattress

Dimensions: 54” x 75”

Wider and longer than twin XL mattresses, full mattresses could be considered the first real adult mattress size, although it may be too small for couples.

Full XL mattress

Dimensions: 54’’ x 80’’

Full XL mattresses have nearly the same dimensions as a full size mattress, however, they’re made with an extra few inches in length to accommodate taller kids, teens, and young adults.

Queen mattress

Dimensions: 60” x 80”

A step up from a full XL mattress, queen mattresses are perfect for adult couples or singles who want a bit of extra wiggle room.

King mattress

Dimensions: 76” x 80”

Like their name implies, king-sized mattresses are considered to be super comfortable, with tons of space for couples to sleep however they want, and enough room for your pets or kid after a particularly scary nightmare

California king mattress

Dimensions: 72” x 84”

The crème de la crème of bedroom goals for most, California king mattresses are pretty massive, and work well for taller than average adults or those who simply want more mattress size.

Note: there are other mattress sizes out there, like Olympic queen or Alaskan king size mattresses, but these aren't as common.

Two young girls lying on a patterned bed under a decorative canopy in a bright, book-lined room.

How do you choose the best bed size for your child?

Choosing a properly sized bed is just as important as a comfortable mattress – especially for kids who are still growing! Proper sleep is vital to the development of a child, and by making sure your kiddo is getting all the rest they need from a young age, you’re setting them up for success.

While assembling furniture and planning out a child’s bedroom can be frustrating, picking the right sized bed can be broken down into a few simple steps. You’re going to want to start by familiarizing yourself with common bed sizes, and asking yourself a few questions:

How much space do you have?

Beds are some of the largest pieces of furniture you’ll have in your home, which means you’re going to want to know exactly how much floor space you have to work with. And yes, unfortunately this means pulling out a ruler or measuring tape – but once you measure the dimensions of your kid’s room size, the hard part is over.

How old is your child?

Every child is different, and age doesn’t always match up with how fast they grow. However, bed sizes are designed with certain age ranges in mind – making your child’s age a decent place to start when deciding on a bed.

Here are the most common bed sizes for specific age ranges:

  • Ages 1-4: cribs and junior beds

  • Ages 6-9: twin beds, bunks, or lofts

  • Ages 10-12: twin or full sized beds, bunks, and lofts

  • Ages 12 and up: full sized, queen, king sized beds

This list isn’t set in stone – your budget, the space you have available, your children’s preferences, and their height and weight should all be considered when planning out their bedrooms or upgrading beds sizes. Sleep is a highly personal activity, and everyone’s different.

Is your child sharing with a sibling?

Another thing to consider is if your kid is going to share their room or the same bed with a sibling. If so, you have a few options. You can either buy two beds, or opt for a bunk bed or loft-style bed. If you’re lacking space in a child’s bedroom, you'll most likely want to look at bunk beds or lofts – these are stacking style beds perfect for limited space.

If none of these options work, you could also simply buy two twin sized beds and place them on opposite ends of your kid’s bedroom, opening up the middle for them to play and study in.

Organize your home with our space-saving beds

At Casa Kids, we’re obsessed with delivering comfortable sleep to your family – modern and modular designs and custom home installations are just a few things included within our catalog of children's beds. Here’s a quick rundown on our space-saving kid’s beds and other furniture we craft:

If you're looking for a bed with plenty of storage space underneath, you're going to want to keep reading. The ideal bed model from Casa Kids in terms of storage would be our loft beds, although you can always use some of our storage drawers under normal beds as well.

Bunk beds

Perfect for a smaller room size, the Cabina Bunk Bed is one of our most modular designs – use it as a standard bunk bed, convert it into two twin sized beds, or go with a daybed and twin size bed combination. Shipped alongside a suspended ladder with easy grip handle cut-outs, you can use the space underneath the Cabina for storage without any hardware in the way.

Modern bunk bed with stuffed animal on lower level, set against a light blue polka-dot wallpaper.

Loft beds

Similar in style to our bunk beds, the Cabina Loft Bed is another excellent option for small bedrooms. Easily converted into a single twin, our loft beds offer even more storage space then our bunks. If your kid wants a chill place for gaming and reading, you can pair it with our detachable desk and hanging tray to create a cozy hideout.

If you’re looking for two beds in one loft-style setup, our Cabina L-Shaped Loft Bed offers even more customization – and fits perfectly within the corner of smaller bedrooms while still providing a roomy sleeping experience.

Our Aspen Loft Bed makes a timely upgrade for teens and young adults who have grown out of bunk beds and need a little more privacy and space to study or relax in. This loft model comes with a large closet and drawer for storage, shelving, stairs, a desk – and of course, the loft bed on top.

Stylish child's bedroom with a bunk bed, integrated desk, and red sofa bed on a gray rug.

Twin beds

A simpler version of our bunk and loft beds, the Cabina Twin Bed is our newest model of minimalist kid’s beds. Simple, sturdy, and made with sustainably harvested baltic birch plywood, this twin comes with ample storage space underneath.

If you’re looking for even more space-saving power, you may want to consider pairing it with our trundle bed, which you can read about below.

Bright children's room with twin beds, orange wall, artwork, and wooden furniture on a beige rug.


Perfect for kiddos who like to hangout in their room, the Cabina Daybed converts from sofa to bed in a matter of seconds. With the same modularity as our twin bed, our daybed is another option if you’re looking to install a pull-out trundle-style bed – this works particularly well in guest rooms or living rooms when used as a couch.

Cozy blue room with bed, shelves, guitar, art supplies, and blue rug.

Trundle beds

The Cabina Trundle Bed pairs with a few of our other children’s beds, including our bunk, twin, and daybed models. Sliding in underneath our other bed frames, this trundle pullout bed was designed specifically for those who want to maximize open-spaces within their home, or simply just need an accessible guest bed for occasional visitors or sleepovers.

We also stock a selection of Murphy Beds – also known as tuck beds – for those who want a room without any clutter at all.

Modern nook with geometric wallpaper, daybed, art, toys, and red accents.

Cribs and Junior beds

Last but not least, the Cabina Crib is our top-selling wooden crib, crafted using the same sustainable birch plywood found we use with our other bed models. With the goal of making a crib that grows alongside your child – three adjustable crib mattress heights are included. If your baby or toddler tends to chew, rest easy knowing we’ve sealed the Cabina Crib with a non-toxic, water-based finish.

If you’re looking for a slightly larger, junior-sized toddler bed – check out our Marino Junior Bed, ideal for kids between ages 2 and 8. If you’ve got a particularly adventurous child who tends to climb out of their crib, this is the perfect option for you.

Nursery with crib, animal art, toys, fluffy rug.

What are the best bed sizes for toddlers?

Babies and toddlers can get a good night’s rest in a few different ways, including sharing your bed, sleeping on crib mattresses, or snoozing on a small toddler bed. According to recommendations by The American Academy of Pediatrics (AAP), the best way for a baby or toddler to sleep is in a “separate but proximate” sleep environment.

Simply put, your infant should sleep in a crib or bassinet in your room, but not in your bed most of the time. The reason for this, according to mountains of research published on this topic, is that tragic cases of sudden infant death syndrome (SIDS) are associated with bed-sharing with parents. In fact, approximately half of all sleep-related infant deaths, including SIDS, occur while sharing a bed with their parents.

Sharing a room with your sleeping baby, however, is associated with a reduced risk of SIDS. That is, sharing your bedroom space but not your bed. With this in mind, the best recommendations for baby or toddler beds are cribs and bassinets!

What are the best bed sizes for bigger kids?

If your child hit an early growth spurt in middle school, you may be struggling to find them a comfortable bed. The weird thing about beds is that as you go up in sizing, sometimes the length decreases instead of increasing.

For example, between a twin and full sized bed, you have a twin XL. A twin has a length of 75’’, a twin XL has a length of 80’’, and a full has a length that goes back down to 75’’. Confusing, right? So, if you’re looking for a big kid bed with a little extra length, the best options are as follows:

  • Twin XL: which measures 39’’ x 80’’

  • Full XL: which measures 54’’ x 80’’

  • Queen or Kings: which have 80’’ lengths but are much wider as well

You don't necessarily need to buy your kid a new bed or king size mattress just because they've grown up a bit, the most important thing is to work within your price range to find a bed your child can comfortably sleep in.

What are the best bed sizes for teens?

Similar to fast-growing and older kids, teens are usually starting to shoot up height, sometimes a little too fast for your wallet! For that reason, as kids transition from childhood to adolescence (around 12 depending on their height), it may be best to invest in a decent full XL or queen sized mattress for them.

Larger mattresses and beds should last the average teen quite a while, potentially even into adulthood if they take good care of them. Obviously, every teen is different, so you’re going to want to make sure they can rest comfortably on whatever size you decide on.

Final thoughts

Finding the best bed size for your kid can be pretty confusing at times, in part due to manufacturers using different labels! This guide has explored the most practical way in which new and experienced parents can decide on a new bed or mattress, but you may still have some more questions.

If you want to know more about specific bed types and other sleep details, make sure to check out the rest of our blog content.