What Size Bed Does Your Child Need? Smaller Beds, Singles and Room to Grow

You want a bed they won't outgrow in five minutes. You would also quite like to open the wardrobe, change the sheets and leave somewhere for the train track.

Then there is bedtime. If you regularly sit beside your child for stories, or find yourself staying a little longer than planned, the bed needs to work for that too.

Choosing a children's bed size is about balancing sleeping room, usable bedroom space and how your family uses the bed. There isn't one size every child needs at a particular birthday, and you don't have to work through toddler, junior and single beds in order.

This guide explains the measurements and the practical differences, using examples from our children's bed collection.

Should you buy a smaller bed or go straight to a single?

This is often the real question behind the size options.

A smaller bed can leave valuable room for playing and moving around. A longer bed can avoid another frame and mattress purchase a few years later. Both are reasonable priorities.

We would start here:

• If your child already has a suitable bed and fits comfortably: there may be no reason to replace it simply because they have reached another birthday.
• If you're buying everything from scratch: compare the complete cost of a smaller setup with a longer bed, including the mattress, protector and sheets.
• If the bedroom is tight: check what a larger bed would take away. Losing access to drawers or most of the play space is a significant trade-off.
• If your child is tall or the current bed is already cramped: a longer sleeping area may be more useful than another small step up.

A compact bed isn't automatically a waste of money. Equally, a child doesn't need an intermediate bed just because the next size is labelled “junior”.

Children's bed sizes explained

Bed sizes usually describe the mattress or sleeping area, shown as width × length. They do not usually describe the complete frame.

Names vary between brands. Always check the numbers rather than assuming that every “junior”, “short single” or “single” bed is the same.

What size bed suits a three-year-old?

There isn't a single measurement that answers this for every family.

For a child who meets the bed's suitability requirements, a smaller sleeping area may be perfectly practical. Another family may choose a full-length bed from the start because their child is tall, the room allows it, or they want to avoid buying another size later.

Keep minimum age and mattress size separate. Our MONIO soft foam beds are recommended from three years, or 36 months, across all four sizes. The Benlemi LUCKY low wooden beds featured here are also recommended from three years. Other models have their own guidance.

A smaller mattress does not make a bed suitable below its minimum age. A larger mattress does not mean you have to wait until your child reaches a particular height to consider it.

When is a toddler or junior size worth considering?

Sometimes the extra floor space matters more than buying the longest bed available.

Perhaps two children share a room. Perhaps the wardrobe has nowhere else to go. Or perhaps the bedroom is where most of the playing happens, and losing that clear patch of floor would be a daily nuisance.

Our 70 × 140 cm MONIO Bouclé bed is the smallest sleeping size in the foam range. The 80 × 160 cm junior bed adds 10 cm of sleeping width and 20 cm of length.

If you're deciding between them, consider how comfortably your child fits now and how soon you would be happy to change beds again. A child already approaching the limits of a smaller sleeping area is unlikely to gain much from another compact purchase.

But if a junior size gives your child comfortable sleeping room and makes the bedroom work better, that is a useful benefit in its own right.

Does a bigger bed have to mean a higher bed?

No. Sleeping size and bed height are separate choices.

You can choose more length without moving to a tall frame. That is useful if you want growing room while keeping access low and straightforward.

For example, our 90 × 180 cm MONIO youth bed and 90 × 200 cm MONIO single bed retain the low soft foam design of the smaller models.

The Benlemi LUCKY low wooden bed also offers several sleeping lengths, including 190 and 200 cm.

Compare the finished sleeping height with the recommended mattress in place. A low-looking frame with a thick mattress may sit higher than you expect. Always follow the model's mattress-depth and safety instructions.

Will a single bed give enough room for bedtime stories?

It depends on how you use it. Sitting on the edge for a book is different from lying beside your child for half an hour.

If you would like more space alongside them, look at width, not just length. Moving from a 90 × 180 cm mattress to 90 × 200 cm adds room at the ends; it doesn't add room beside your child.

Selected Benlemi LUCKY beds offer 120 cm and 140 cm sleeping widths. These may be worth considering if time together in the bed is a regular part of your evenings and the bedroom can accommodate the extra width.

Before an adult joins a child on any bed, check the permitted use and combined load limit for the frame and mattress. A bed being physically large enough is only part of the answer.

And if a wider bed would swallow the room, a comfortable chair beside a single may be the more useful arrangement. You don't have to solve every bedtime need with a bigger mattress.

How do you know their current bed is getting too small?

Look at your child in the bed rather than relying only on an age chart.

• Can they stretch out comfortably without being pressed against the ends?
• Do they have room to turn and change position?
• Are they regularly complaining about the available space?
• Have they reached any size, weight or usage limit specified for the bed?

Being an active sleeper doesn't automatically mean the bed is too small, and curled-up sleeping doesn't necessarily mean they need a longer one. Look for a consistent lack of comfortable space.

We wouldn't promise that 70 × 140 cm lasts until one particular birthday, or that 80 × 160 cm suits every child in a fixed age bracket. The measurements are useful; an exact expiry date usually isn't.

Measure the whole bed, then test the room

This is the check we would put near the top of any buying list.

A mattress-sized rectangle on the floor can underestimate the space needed for padded sides, a headboard or wooden rails.

For example, the MONIO Bouclé junior bed has an 80 × 160 cm sleeping area but measures 107 × 184 cm overall. That extra width and length needs to be included in your layout.

Try this before ordering:

1. Find the overall measurements for the exact model and size.
2. Mark the footprint with masking tape suitable for your floor.
3. Open the bedroom door, wardrobe and drawers fully.
4. Check the route to the bed, including access for changing sheets.
5. Look at what is left for playing, storage and moving around.

If you're considering drawers or a pull-out bed, mark those in the open position too. For a house-shaped frame, check the roof height against any sloping ceiling.

It is much easier to move some tape than an assembled bed. Our practical guide to setting up a toddler bedroom has more ideas for balancing furniture and usable floor space.

UK single or European single: check before buying the mattress

A standard UK single mattress is usually 90 × 190 cm. A European single is 90 × 200 cm.

They have the same width, but the European single is 10 cm longer. A UK single mattress is therefore too short for a bed requiring 90 × 200 cm.

Our MONIO 90 × 180 cm model needs its own matching length too. Don't order by the word “single” alone, and don't fill a mismatch with cushions or folded bedding.

If you already own a mattress, check its exact measurements and condition before choosing a frame around it. Confirm the required mattress type and thickness as well as width and length.

It is also worth checking fitted sheets and protectors before you settle on a size. Include these in your budget, particularly when moving away from bedding you already own.

Will a new bed help them stay in their own room?

A bed that fits comfortably can make the room more practical and inviting. It cannot promise fewer wake-ups or an end to visits to your bedroom.

If you're buying mainly because you hope a bigger bed will change their sleep, pause and separate that hope from the things you can check: space, access, suitability and comfort.

There are good reasons to replace a bed. A guaranteed full night's sleep isn't one we would attach to any size.

Which size would we choose?

We would narrow it down according to the problem you need to solve:

• “The room is small.” Compare complete frame dimensions. A smaller mattress helps only if the whole bed leaves the space you need.
• “I don't want to buy twice.” Consider a longer low bed that meets your child's needs now and offers room to grow.
• “I often lie beside them.” Compare width and permitted combined weight, rather than choosing extra length alone.
• “Their bed still works.” Keep using it within its instructions and limits. You don't need to replace it to keep up with a size label.

The aim is a bed your child can use comfortably in a bedroom that still works during the day.

You can browse our full range of children's beds to compare soft foam, low wooden and house-shaped designs. If you're between two sizes, email us with your child's age and height, the models you're considering and your available room measurements. We'll help you check the differences before you order.