Trundle Bed for Kids: Which Mattress Fits and How Much Space Do You Need?

A trundle bed for kids is worth it when a second child sleeps over now and then – a sibling, a cousin, a best friend – and there’s no room for a second bed. Three things decide whether it works: a mattress that fits the trundle drawer exactly (on our beds 10 cm shorter than the bed and no more than 10 cm deep), enough clear floor in front of the bed to pull it out, and a fall guard on the main bed above.

Trundle, underbed drawer or pop-up bed: what’s the difference?

Shops use several names that don’t mean the same thing. Before you compare beds, here’s a quick overview:

Term	What it is	For sleeping?
Underbed drawer	storage under the bed, often on castors	no
Trundle drawer	drawer with a slatted base for a second mattress	yes
Pop-up trundle	lower bed that lifts to the height of the main bed	yes, as one wide surface

On our beds you choose this as the drawer with a sleeping function. The bottom of the drawer is a proper slatted base, just like in the main bed. The trundle sits just above the floor, so a fall from height isn’t an issue down there.

Who is a trundle bed for kids really for?

A trundle earns its place in these situations:

• Sleepovers: a best friend stays the night, the cousins come for half-term. The guest bed is ready in two minutes – no airbed on the floor.
• Siblings who like to sleep close: many children settle better when a brother or sister is right next to them. A trundle is a lovely compromise without two beds in the room.
• Unsettled phases: after a house move, during an illness or a run of bad dreams, it often helps when a sibling sleeps close by for a few nights.
• Box rooms and small bedrooms: in a room of 6 to 10 m², there’s still floor to play on during the day, because the second bed slides away under the first.

A trundle makes less sense if two school-age children share a room every single night. Then a bunk bed or two single beds is usually more comfortable (more on that below).

Which mattress fits a trundle drawer?

This is the question parents ask us most often – and most retailers hide the answer in the small print. On our beds there’s one simple rule: the trundle mattress is 10 cm shorter than the bed and no more than 10 cm deep. That way the drawer slides under the bed easily, even with bedding inside.

Bed size	Trundle mattress	Max. depth
80×160 cm	80×150 cm	10 cm
80×180 cm	80×170 cm	10 cm
90×180 cm	90×170 cm	10 cm
80×190 cm	80×180 cm	10 cm
90×190 cm	90×180 cm	10 cm
90×200 cm	90×190 cm	10 cm

Good to know:

• Don’t buy the same mattress as for the main bed. A 90×200 mattress won’t fit the trundle of a 90×200 bed – it’s too long and usually too deep.
• Firm, not soft: your child needs a firm, supportive children’s mattress in the trundle too. Folding foam guest mattresses are fine for one night, not for regular sleep.
• Check the depth: many children’s mattresses are 12 to 16 cm deep. On our product pages we recommend the COCCOPURE Children’s Mattress and the OPTIMA Children’s Mattress for the trundle, because they stay within the 10 cm maximum.
• UK single sizes: 90×190 cm is the standard UK single. On a 90×190 bed the trundle takes a 90×180 mattress, which isn’t a standard UK size – so choose the trundle mattress together with the bed rather than off the shelf.

You’ll find every size in our children’s mattresses category. For other bed sizes, the matching trundle mattress is always listed on the product page.

How much space does a trundle bed need?

During the day, a bed with a trundle takes up no more room than a normal single bed. At night, a second sleeping surface appears in front of it. Plan it like this:

1. Measure the bed width: the open trundle needs about as much clear floor in front of the bed as the bed is wide – for a 90 cm bed, around 90 cm.
2. Add a walkway: so nobody has to climb over the guest bed at night, leave another 40 to 50 cm, for example towards the door.
3. Check for obstacles: a thick rug, a chest of drawers or a toy box mustn’t be in the way. The trundle runs on castors and needs a level floor; it rolls most easily on wooden floors or short-pile carpet.
4. Only on beds with legs: the trundle needs space under the bed. That’s why our beds with a drawer stand on 20 cm legs; the Mini versions that sit on the floor have no drawer.

Measure before you buy and mark the area on the floor with masking tape – you’ll see straight away whether the door and the wardrobe still open freely.

Every night or now and then: how comfortable is a trundle?

For guests and occasional sleepovers, a trundle is ideal. If one child is going to sleep in it every night, that works too – with a few habits:

• Air it: pull the drawer out for a while in the morning and let the mattress breathe before you slide it back. The slatted base helps air reach the mattress.
• Keep the bedding inside: a light pillow and a thin duvet fit in the drawer, so the guest bed is ready in seconds.
• Make it theirs: with siblings, it helps if the lower bed has its own bedding and a fixed spot for the favourite teddy. Then the younger child doesn’t feel like a guest in their own room.

To be honest: a 10 cm mattress is a little thinner than the one in the main bed. It’s fine for children up to the end of primary school; for bigger teenagers it’s better kept for the odd night.

From what age can a child sleep in a trundle bed?

The trundle sits close to the floor and has no fall guard of its own. So it suits children who already sleep in a normal bed – usually from around 2 to 3 years. Babies shouldn’t sleep in a trundle drawer; they need their own cot with a firm, flat mattress.

The same rules apply to the trundle as to any children’s bed: a firm mattress that fits the drawer exactly, no gaps at the sides and no thick pillow for little ones. RoSPA explains how falls and other accidents happen to young children at home and how to prevent them (RoSPA: accidents to children).

One point many parents overlook: the child in the top bed. When the trundle is pulled out at night, the sibling lies right in front of the main bed. So fit the fall guard on the main bed on the trundle side. On our house beds you can mount it on the left or the right and take it off later.

Trundle or bunk bed? Alternatives for two children

A trundle isn’t always the best answer. Here’s how to decide:

• Bunk bed: if two children share a room every night, bunk beds save just as much floor space – and each child gets a full-size mattress. Under BS EN 747, the top bunk is only suitable from 6 years.
• Two single beds: in a bigger room, or for children with very different bedtimes, this is often the calmest option.
• One wider bed on the floor: if it’s mainly you lying down with your child at bedtime, a wider bed is the better choice. Read more in our guide Double Floor Bed for Kids: Who a 140×200 Bed Is Really For.
• Drawer for storage only: if you don’t need a second bed yet, choose the large drawer or two small drawers for bedding, toys and clothes.

Which Little Loft beds come with a trundle?

At Little Loft you can choose the sleeping function on every bed “with drawer”, for example the LUNETTA Children’s Bed with Drawer, the ASTRIA Children’s Bed with Drawer or the SOLETTA Children’s Bed with Drawer. If you’d rather have a bed without a roof, the LUNA Children’s Bed with Drawer is a simple design with fall guards.

Every bed is made from pine wood (FSC), handmade in Europe and finished with a water-based lacquer. We’re a Swiss family brand trusted by over 3,200 families, and we give a 5-year guarantee on the bed frame, including the drawer, slatted base and fittings.

Verdict: a trundle bed for kids works when the mattress fits

A trundle bed for kids gives you a second sleeping place without making the room smaller. To make it truly comfortable, choose a mattress that’s 10 cm shorter than the bed and no more than 10 cm deep, keep about one bed width plus a walkway clear in front of the bed, and fit the fall guard on the trundle side. If two children will share every night for years, take a look at a bunk bed too.

Not sure which model suits you? Our Bed Advisor helps with a few quick questions – or put together size, colour, drawer and fall guard in the 3D configurator and see the bed from every side.

Frequently asked questions about a trundle bed for kids