Bunk Bed Mattresses

A bunk bed mattress is a standard single at 90 x 190cm, but no deeper than 15 or 16cm. That depth limit is the key difference, and it is a safety measure rather than a comfort preference.

Guard rails are designed to sit a set height above the mattress surface. Most single mattresses available on the high street are 20cm or deeper, and placing one on a top bunk removes that clearance. The rail is still there; it just isn’t doing what it was built to do.

Everything here is built at 15cm or less specifically for bunk beds, high sleepers, mid sleepers, cabin beds, and trundles. All are made in the UK, vacuum packed and rolled so they come up a ladder easily.

Bunk bed mattress size

Bed Mattress size

Maximum depth

Standard bunk, top and bottom

90 x 190cm, 15 to 16cm on the top bunk

Shorty bunk

75 x 175cm, 15 to 16cm

Continental bunk

90 x 200cm, 15 to 16cm

Triple sleeper, bottom bunk

120 x 190cm small double, usually no limit

Triple sleeper, top bunk

90 x 190cm, 15 to 16cm

Trundle or pull-out

Matches the bed above, around 10cm

Most bunk beds take two standard UK singles at 90 x 190cm. This is the same width and length as a normal single bed; only the depth differs.

The bottom bunk usually has no depth restriction since there is no rail above it. Most families buy two identical mattresses anyway because children swap, and you will hear about it if one is noticeably better.

Trundles need around 10cm so the mattress clears the frame above when it slides away. A standard mattress physically will not fit.

How deep can a bunk bed mattress be?

Usually 15 or 16cm maximum on the top bunk, or roughly 6 to 7 inches. The exact figure is set by the bed manufacturer and stated on each bed’s product page because it depends on their guard rail height.

Why it matters practically: BS EN 747 requires the safety barrier to extend a set distance above the top of the mattress, so the top of the mattress should sit at least 16 cm below the upper edge of the guardrail to leave enough clearance. A 20cm mattress in place of a 15cm one raises the sleeping surface by 5cm and reduces that barrier by the same amount. Mattresses over 16cm can be unsafe on the top bunk if they reduce that clearance.

Fit and safety come before comfort features when choosing a bunk bed mattress. It’s also important to ensure the mattress is a secure fit under the guard rails and sits snugly against the frame, with no gaps at the corners or sides. A breathable mattress is also preferred on bunks because airflow is more limited. A loose or ill-fitting mattress can create dangerous gaps and trapping hazards.

Re-check the figure whenever you replace a mattress, not just when you buy the bed. It is the most commonly missed step because people replace like for like without realising the old one was the wrong depth in the first place. If an older teenager or an adult will use the bed, ask us and we’ll confirm the manufacturer’s load limit.

Our bunk bed mattresses

ComfortSleep 15

Reflex foam. Firm, supportive, and the most affordable of the three. ComfortSleep 15 is crafted to keep that practical, budget-friendly positioning. Good for younger children, lighter body weights, and the bottom bunk of a bed that gets occasional use. For kids, it’s also worth choosing a mattress with a removable, washable cover, which makes it easier to keep clean.

Eight sizes: shorty, small single, single, continental single, small double, continental small double, double, continental double. Bunk bed mattresses are available in single and small single sizes. Most bunk bed mattresses are compatible with small single sizes.

MemoryDream 15 Memory Foam Mattress

Memory foam over a reflex base. Contours to the body, and it is quiet. Low-profile foam or hybrid mattresses also suit bunk beds because they still provide good support. That matters more on a bunk than people expect: a sprung mattress on the top bunk can be heard from the bottom one, so it helps to avoid extra distractions.

Eight sizes, shorty to continental double.

PocketRest 15

Pocket springs. More airflow so it sleeps cooler, with a traditional feel and a bit of bounce. A single mattress can work well on the top bunk specifically since heat rises and the top bunk runs two to three degrees warmer than the bottom. This option may suit children who sleep hot or prefer a more traditional feel.

Single, continental single, small double, double.

TrundleEase 10

Built at 10cm for pull-out and trundle beds. This is the one that clears the frame when the trundle slides back. Once fully expanded, it’s ready to use. Its vacuum-packed design also makes delivery easier for a trundle mattress.

Eight sizes, shorty to continental double.

One thing specific to bunks: motion transfer

On a bunk bed, one child’s movement can be felt or heard by the other. It is the complaint parents raise most often after the bed is built, and it is not something the frame can fix.

Pocket springs move independently, so a restless sleeper on the top bunk disturbs the one below far less than an open coil mattress would. Foam transmits almost nothing, and foam and hybrid bunk bed mattress types usually give good pressure relief and motion isolation for shared use, helping strike the right balance for lighter sleepers, which is why MemoryDream is the quietest of the three.

If the children are light sleepers or if one goes to bed considerably later than the other, this matters more than firmness does.

Choosing by sleeping position

A practical way to pick between the three: bunk bed mattresses commonly come in medium and firm options, and choosing a suitable firmness for the sleeper’s position is often the perfect place to start.

Sleeps

Needs

In our range

On their side

Enough give at the hip and shoulder so pressure points aren’t loaded

MemoryDream 15, memory foam contours

On their back

A medium-firm surface that keeps them evenly supported

PocketRest 15 or ComfortSleep 15

On their front

Firmer, so the hips don’t sink and arch the lower back

ComfortSleep 15

All over the place

Something that adapts and stays quiet

MemoryDream 15

Which is the best bunk bed mattress?

It depends on the child rather than the bed, so if you're unsure which model to choose, use the guide below.

• If they sleep hot: PocketRest 15, pocket sprung with more airflow.
• If someone sleeps underneath: MemoryDream 15, as foam is quieter than springs.
• For a younger or lighter child: ComfortSleep 15, firmer reflex foam.
• For a restless sleeper: MemoryDream 15, memory foam that contours and holds its shape, so there is less movement to disturb anyone.
• For occasional or guest use: ComfortSleep 15, the best value.
• For a trundle or pull-out: TrundleEase 10, the only one that fits.

Medium to medium-firm suits most children. Too soft lets the hips sink and the spine curve; too firm creates pressure points at the shoulder and hip. Firmer is the safer error on a growing body, and the right feel should stay comfortable and supportive through the night, giving them a supportive sleep surface.

A well-made 15cm mattress supports a child’s weight perfectly well. Depth and comfort aren’t the same thing, and the extra depth in an adult mattress is there for adult body weight.

Mattresses for high sleepers

High sleepers follow the same rules as bunks, so they need mattresses specifically designed for bunk beds or raised beds to fit safely and functionally. Lighter mattresses are often the better choice on raised beds so they do not add unnecessary strain to the structure. A high sleeper has guard rails and a maximum mattress depth, usually 15 or 16cm, and the whole 15cm range fits.

One thing specific to high sleepers: if your teenager needs more support than 15cm gives, the answer is a different bed rather than a deeper mattress. Depth on a raised bed isn’t negotiable.

See all high sleeper beds

Mattresses for mid sleepers

Mid sleepers sit lower than high sleepers but most still have guard rails, so the same depth limit applies. Check the figure on your bed’s page.

The mattress size is usually a standard single at 90 x 190cm, though some compact frames take a small single at 75 x 190cm and shorty models take 75 x 175cm.

See all mid sleeper beds

Mattresses for cabin beds

Cabin beds vary more than any other type. A low cabin bed with no guard rails takes any depth you like. A higher one with rails has the same 15 or 16cm limit as a bunk.

Check the height to the mattress and whether there are guard rails before choosing a depth. If in doubt, 15cm is safe on any of them.

See all cabin beds

Mattresses for loft beds

Loft bed is the same thing as a high sleeper; the term is more common in the US than in the UK. Same 15 or 16cm depth limit, same standard single size.

How many will you need?

• Standard bunk: two, both within the top bunk’s depth limit
• Bunk with a trundle: three, two at 15cm and one at 10cm
• Triple sleeper: a small double for the bottom and a single for the top
• Quadruple bunk: four
• High sleeper, mid sleeper or cabin bed: one

Counting them is the most commonly forgotten part of a bunk bed order, so make it simple to avoid mistakes. A bed arrives, gets built, and there is nothing to sleep on.

Things that catch people out

Assuming a standard single fits a shorty. A shorty bunk needs 75 x 175cm. A standard single is 15cm too long.

Using a supermarket mattress on the top bunk. Almost all are 20cm or deeper, and regular mattresses are often too deep for standard bunk beds.

A standard mattress on a trundle. It won’t slide away, and you will only find out once it is unrolled.

Buying one when you need two. Or two when you need three.

Forgetting a protector. Cleaning a mattress on a top bunk is genuinely difficult. Take it down to the floor rather than trying to clean it in place, and a protector saves you doing that at all.

Getting it onto the bed

A rolled, vacuum packed mattress is easier to carry upstairs and lift onto a top bunk than a conventional one. Unroll it on the bunk rather than on the floor.

Allow 24 to 48 hours for it to fully expand before making the bed. It will look thinner than expected for the first few hours.

Bunk Bed Mattresses: Common Questions

What size mattress fits a bunk bed?

Most bunk beds take a standard UK single at 90 x 190cm, the same footprint as a standard single mattress. Shorty bunks take 75 x 175cm and continental bunks take 90 x 200cm.

What depth mattress for a bunk bed?

Usually a maximum of 15 or 16cm on the top bunk. The exact figure is on your bed’s product page.

Why does bunk bed mattress depth matter?

Guard rails sit a set height above the mattress surface. A deeper mattress raises the sleep surface and reduces that clearance, so the rail becomes less effective. Safety also depends on choosing a mattress that complies with local standards such as British Fire Regulations (BS 7177).

What are the dimensions of a bunk bed mattress?

90cm wide by 190cm long, at 15cm deep or less. In imperial that is 3ft by 6ft 3.

Can I use a thicker mattress on the bottom bunk?

Usually yes, since there is no guard rail above it. Most people buy two identical ones anyway.

How many mattresses do I need for a bunk bed?

Two. Three if it has a trundle, and the trundle one is shallower at around 10cm.

What mattress fits a trundle bed?

Around 10cm deep so it clears the frame above when it slides away. A standard mattress won’t fit.

Foam or pocket sprung for a bunk bed?

Foam is quieter, which matters when someone is sleeping underneath. Pocket sprung is cooler, which matters more on the top bunk. Either works, and both can give a supportive sleep surface when the depth is correct, and some parents prefer trusted brands for extra reassurance.

Are 15cm mattresses comfortable enough?

Yes, for a child. A well-made 15cm mattress supports a child’s weight perfectly well. The extra depth in an adult mattress is there for adult body weight. Choosing the right depth helps with safety too, giving extra peace of mind. Most kids bunk bed mattresses should also be replaced around every 7 years, and maintaining support and shape helps with hygiene and a better night's sleep.

What is the best mattress for a bunk bed?

PocketRest 15 if they sleep hot, MemoryDream 15 if someone sleeps underneath or they are a restless sleeper, ComfortSleep 15 for a younger child or a guest bed.

Is the top bunk hotter than the bottom?

Yes, usually by two to three degrees because heat rises. A pocket sprung mattress and a lower tog duvet both help.

Do you sell mattresses for high sleepers and mid sleepers?

Yes, the same range, with sizes and depths in stock across our mattress brands. Any bed with guard rails has the same depth limit as a bunk.

Buying the bed too? Read our bunk bed mattress guide, or browse all bunk beds.