Single Mattresses in Memory Foam and Pocket Sprung
A single mattress is the size most people buy first and buy most often: it goes in a child's room, a box room, a guest room, and on every bunk bed and cabin bed in the house.
There is only one single size in the UK, so the decision is not about dimensions. It is about what the mattress is made of, how firm it is, and how deep it can be.
Single mattress size
A UK single mattress measures 3ft x 6ft 3in (90 x 190cm). That is the standard, and it does not vary between makers, so any single mattress fits any single bed frame sold in the UK.
Two things trip people up. The first is length: 6ft 3in is 190cm, which is comfortable for most people but short for anyone over about 6ft 2in. The second is that a continental single is 90 x 200cm — the same width, 10cm longer — so a mattress bought abroad will not sit correctly in a UK frame, and a UK mattress leaves a gap at the foot of a continental one.
The width is the number that matters for the room. At 3ft, a single takes up less floor than most people expect, and two singles side by side occupy roughly the same width as a super king.
Memory foam single mattresses
Memory foam responds to body heat and weight, so it forms to the shape of whoever is lying on it and spreads their weight instead of resisting it at the hips and shoulders. The result is a mattress that feels like it is holding you rather than pushing back.
It suits a side sleeper particularly well, because the shoulder and hip sink in while the waist stays supported, which keeps the spine straight rather than bowed. It also transmits almost no movement, though on a single bed that matters less than it would on a double.
The known trade-off is heat: foam holds warmth where a sprung mattress lets air through. Some foams are made with gel through the layer specifically to counter this, and they sleep noticeably cooler than plain foam. If the bedroom is warm, or the sleeper runs hot, that is the version to look for.
Pocket sprung single mattresses
A pocket sprung mattress carries each spring in its own fabric pocket, so the springs compress independently rather than as one connected unit. Where an older open-coil mattress moves as a whole and pushes back evenly, a pocket sprung one supports each part of the body by however much that part needs.
The practical differences from foam are airflow and feel. Air moves between the pockets, so a pocket sprung mattress runs cooler through the night. And the support is springier rather than sinking, which suits a back or front sleeper, and anyone who dislikes the enclosed feel of foam.
Spring counts appear in the names of these mattresses, and higher numbers mean more, smaller springs across the same area, so the support follows the body more closely. It is a genuine difference, but it is not the only one: what sits on top of the springs matters as much. A pillow top adds a separate padded layer stitched over the surface, which softens the immediate feel without changing the support underneath.
Firm single mattresses
Firmness is about the surface, not the quality. A firm mattress holds the body higher and lets it sink in less; a softer one lets the shoulders and hips settle further before it takes the weight.
Firm suits back and front sleepers, heavier sleepers of any kind, and anyone who finds a soft mattress makes getting out of bed harder work. Side sleepers usually want less firmness, because the shoulder needs somewhere to go.
The word is not standardised across the trade, so one maker's firm is another's medium. The useful comparison is within a single range rather than between different ones.
Single mattresses for bunk beds and children's beds
Bunk beds, cabin beds, mid sleepers and high sleepers all take a single mattress, which is why this size sells more than any other.
They also all have a guard rail, and that changes what you are buying. On a flat bed the mattress only has to fit the frame. On a raised bed it has to fit the frame and stay low enough that the guard rail still does its job.
Single mattress depth
Depth is the measurement that matters on any raised bed, and it is the one people forget because it never matters on an ordinary bed.
The rule is simple: enough of the guard rail must sit above the sleeping surface to hold a sleeping child in. A mattress that is too deep raises the surface towards the top of the rail and reduces how much of it is doing anything. Most bunk bed makers state a maximum depth for exactly this reason, and it is worth finding that figure for your bed before choosing the mattress, not after.
The same logic applies to the top bunk and to a high sleeper, where the drop is greater. On the bottom bunk of a bunk bed, depth is usually limited instead by the headroom to the bunk above.
Single mattress FAQs
What size is a single mattress?
3ft x 6ft 3in, or 90 x 190cm. This is the UK standard and it is the same across every maker, so any single mattress fits any UK single bed frame.
How long is a single mattress?
6ft 3in (190cm). A continental single is 200cm long, so it will not sit correctly in a UK frame.
How thick should a single mattress be?
On an ordinary single bed, depth is a matter of preference and price rather than fit. On a bunk bed, a cabin bed or a high sleeper it is a safety measurement, because a deeper mattress leaves less guard rail above the sleeping surface. Check the maximum depth for your bed before choosing.
What is the difference between memory foam and pocket sprung?
Foam moulds to the body and holds warmth. Pocket springs support each area independently and let air through, so they sleep cooler and feel springier. Side sleepers often prefer foam; back and front sleepers often prefer springs.
Which single mattress is best for a bunk bed?
One within the maximum depth your bunk allows. Beyond that, either construction works, though a lighter mattress is easier to handle when changing the bedding on a top bunk, which is a job done from a ladder or from the steps.
Do all single beds take the same mattress?
In the UK, yes. Single beds, bunk beds, cabin beds, mid sleepers and high sleepers all take a 3ft x 6ft 3in mattress. Only the depth limit changes between them.