Small Double Mattresses in Memory Foam and Pocket Sprung

The small double is the size people arrive at when a single is not enough and a double will not fit. It is also the size almost nobody can name the dimensions of, which is why most people land here asking what it actually measures.

Small double mattress size

A small double mattress measures 4ft x 6ft 3in (120 x 190cm).

The number that matters is the width. A standard double is 4ft 6in (135cm), so a small double is 6in (15cm) narrower and nothing else about it changes: the length is identical at 6ft 3in (190cm), so anyone who fits a double lengthways fits a small double.

Those 6in are what make it work in a room. A bedroom that cannot take a double, once you account for a wardrobe door swinging or space to walk past the foot, will very often take a small double with room to spare. It is the difference between a bed you edge around and a bed you walk past.

The honest arithmetic for two people: 120cm shared is 60cm each, which is narrower than a single bed is for one person. As an occasional guest bed for two, or as a generous bed for one, it works well. As the main bed for two adults every night, most people find it tight.

Three quarter beds and 3/4 mattresses

A three quarter bed is the older name for the same thing, and you will still see it written as a 3/4 bed, particularly on secondhand frames and in house listings.

In current use it means 4ft, so a 3/4 mattress and a small double mattress are the same purchase. The caution is with older frames: bed widths were less standardised before the modern UK sizes settled, and a genuinely old three quarter frame can measure something other than 4ft. If the bed is inherited or secondhand, measure the inside of the frame rather than trusting the name.

Memory foam small double mattresses

Memory foam responds to body heat and weight, forming to the sleeper and spreading their weight rather than resisting it at the hips and shoulders.

It has a particular advantage at this width. Foam transmits very little movement across the surface, so on a bed where two people are already closer together than they would be on a double, one person turning over is much less likely to wake the other. If the small double is shared, that matters more here than it would on any larger size.

The trade-off is heat, since foam holds warmth where springs let air through. Foams made with gel through the layer sleep noticeably cooler, and are worth looking for if the bedroom is warm.

Pocket sprung small double mattresses

A pocket sprung mattress carries each spring in its own fabric pocket, so the springs compress independently rather than as a connected unit, supporting each part of the body by however much it needs.

Air moves between the pockets, so it runs cooler through the night than foam, and the feel is springier rather than sinking, which suits back and front sleepers and anyone who dislikes the enclosed sensation of foam. Where a mattress carries a pillow top, that is a separate padded layer stitched over the springs, softening the immediate feel without changing the support underneath.

Firm small double mattresses

Firmness describes the surface rather than 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 taking the weight.

Firm suits back and front sleepers, heavier sleepers, and anyone who finds getting out of a soft bed harder work than it should be. Side sleepers usually want less, because the shoulder needs somewhere to go. The word is not standardised across the trade, so comparing firmness within one range tells you more than comparing between different ones.

Small double mattress FAQs

What size is a small double mattress?

4ft x 6ft 3in, or 120 x 190cm. The length is the same as a double; only the width differs.

What is the difference between a small double and a double mattress?

6in (15cm) of width. A double is 4ft 6in (135cm) wide, a small double is 4ft (120cm). Both are 6ft 3in (190cm) long.

Is a 3/4 mattress the same as a small double?

In current use, yes: both mean 4ft x 6ft 3in. Older three quarter frames predate the modern standard sizes, so measure the frame if it is an antique or secondhand piece.

Can two adults sleep on a small double?

Comfortably as an occasional guest bed, and it suits couples who sleep close. At 120cm it gives each person 60cm, which is less than a single bed gives one person, so as an everyday bed for two it feels narrow to most people.

Does a small double take double bedding?

Fitted sheets need to be small double specifically, since a double fitted sheet is too wide and will not stay tucked. A double duvet works well on a small double and many people prefer the extra overhang.

Will a small double mattress fit a double bed frame?

No. It would leave a 6in gap across the width of the frame. The mattress and the frame have to be the same size.