A Small Double (4ft) and a Double (4ft 6) sound close, and on paper they are only 15cm apart. In a bedroom that difference can decide whether the room feels comfortable or cramped, and in the bed it changes how much space each sleeper gets. This guide compares the two sizes on room fit, sleeping space, bedding and everyday use, so you can pick the right one.

The sizes at a glance

  • Small Double: 4ft wide (about 120cm) and 190cm long
  • Double: 4ft 6 wide (about 135cm) and 190cm long

Both are the same length. The only difference is the width, and the 15cm is about the width of a large hardback book. It matters more than it sounds. Check the exact dimensions on each product page, because some mattress and bed sizes differ slightly between makers.

How much space each sleeper gets

Shared between two people, a Small Double gives each person 60cm of width. That is about the width of a standard cot, and less than the 75cm or more most adults take up in their sleep. A Double gives 67.5cm each, which is more comfortable but still tight for two adults. If two adults will share the bed every night, a king size bed at 150cm is the more comfortable choice. For one adult, a Small Double is a generous single bed; for a single sleeper who likes to spread out, a Double gives plenty of room.

Which suits your room?

With 60cm of walking space on each side, a Small Double needs a room about 2.4m wide and a Double about 2.55m wide. If the bed is against one wall, you can fit either in a much smaller room. Small Doubles are common in box rooms, guest rooms, loft conversions and rooms where the door or wardrobe limits the space. If your room is at least 2.6m wide and you want a comfortable adult bed, a Double is usually the better choice. For tips, see our guide to measuring your bedroom for a new bed.

Bedding and accessories

Double bedding is easier to find than Small Double, because the 4ft 6 size is the UK standard. That means more choice and usually lower prices for sheets, duvets and mattress protectors. Small Double bedding is available but in a narrower range. If you use a standard double duvet on a Small Double bed, it will overhang, which can look untidy but also keeps you warm.

Mattress and bed choice

Almost every mattress type is available in both sizes, including pocket sprung, memory foam and orthopaedic. Our mattress range covers sizes from Small Single to Super King. On the bed side, many of our divan beds, ottoman storage beds and bases come in both Small Double and Double, with a matching headboard in the same width.

Who should choose which?

Choose a Small Double if:

  • the bed is for one adult and the room is small
  • you are furnishing a box room, guest room or attic room
  • you want a bed that feels bigger than a single without taking over the room

Choose a Double if:

  • the bed will be shared by two people occasionally or every night
  • you like to spread out when you sleep
  • you want the widest choice of bedding and accessories
  • the room is at least 2.6m wide

Consider a King if:

  • two adults will share the bed every night and the room has space for 2.7m of width

Storage on a smaller bed

If you are choosing a smaller bed because space is limited, storage becomes more important. An ottoman base lifts to open one large space for bedding and clothes, and a divan with drawers gives everyday access. Either can free a wardrobe and make the room feel less cluttered. See our guide on what to store in an ottoman bed.

Comfort in practice: what 15cm feels like

On paper, 15cm sounds small. In practice, it shows up in three situations.

Sleeping alone

A single adult in a Small Double has plenty of room to turn, with space for a pet or a child’s visit. A Double gives more freedom to spread out and keeps bedding and pillows from falling off the side. If you move a lot in your sleep, the extra width is noticeable.

Sharing the bed for a few nights

For occasional guests, a Small Double works as a compact double. A couple can share it for a weekend, though it will be snug. A Double is more forgiving, and guests are likely to sleep better.

Sharing the bed every night

For two adults who sleep together every night, a Small Double is too small and a Double is the minimum. Many couples find a king size far more comfortable.

Room layouts: what fits where

  • A box room of about 2m by 2.5m: a Small Double against a wall leaves a narrow walkway. A Double may be too tight.
  • A small double bedroom of about 2.8m by 3m: a Double fits with space for bedside tables and a wardrobe.
  • A loft room with sloping ceilings: a Small Double is easier to fit under the slope, with a low headboard.

If you are unsure, tape the bed outline on the floor. Our guide to measuring a bedroom explains how.

Mattress choice at 4ft and 4ft 6

Pocket sprung, memory foam and orthopaedic mattresses are widely available in both sizes. The Double has the widest choice, including more fabric and tension options. If you want a specific mattress, check that it comes in the size you want. Our mattresses come in Small Single, Single, Small Double, Double, King and Super King.

Upgrading later

If you buy a Small Double now and later move to a bigger room, you will need a new base and mattress. If you think you may upgrade, a Double is a safer long-term choice. If you plan to stay in a small room, a Small Double with built-in storage can be perfect.

Storage matters more in smaller beds

Both sizes are available with an ottoman base or divan drawers. With less floor space, the storage under the bed often makes the difference between a calm room and a cluttered one. Read our small bedroom storage ideas for more.

Common questions

Is a small double big enough for two people?

For short-term use, yes. For regular use, a Double or King is more comfortable.

Can I use a double mattress on a small double base?

No. The mattress and base need to match in size, or the mattress will overhang and wear unevenly.

What is the best size for a guest room?

A Double suits most guest rooms because it is the most flexible, and it gives couples a reasonable amount of space.

All of our beds are handmade in the UK with free delivery to mainland UK in 5 working days, and come with a 3-year warranty. Browse the full range of double beds to compare styles.