Start with the mattress dimensions
Choosing a new bed is not only a question of style. The right bed should provide enough sleeping space, fit the room comfortably and leave enough clearance for everyday movement. Taking measurements before you shop can prevent problems with doors, wardrobes, bedside tables and delivery access.
Bed sizes are usually described by the mattress they take. The frame itself will normally be wider and longer than the mattress, particularly where it includes a deep upholstered headboard, side rails, wings, drawers or a decorative footboard.
| UK bed size | Mattress dimensions | Best suited to |
|---|---|---|
| Single | 90 × 190 cm | One adult, child or guest room |
| Small Double | 120 × 190 cm | One adult wanting more room, or two people with limited space |
| Double | 135 × 190 cm | Two adults in a standard bedroom |
| King | 150 × 200 cm | Two adults wanting more width and extra length |
| Super King | 180 × 200 cm | Two adults wanting generous personal space |
A single mattress is 90 cm wide, while a double is 135 cm wide. That extra 45 cm makes a noticeable difference for two people, but it also affects how much floor space remains for storage and circulation. A king-size mattress adds length as well as width, which can be helpful for taller sleepers.
Measure the room, not just the old bed
A common mistake is to measure an existing mattress and assume the new bed will occupy the same area. Measure the full width and length of the current frame, then compare it with the overall dimensions of the new model. Use masking tape or removable markers on the floor to outline the proposed bed footprint and check that drawers, wardrobes and doors can still open fully.
Keep a clear route around the bed wherever possible. If bedside tables are part of the layout, include their width in the plan rather than adding them afterwards.
Account for the headboard and frame
A bed with a tall or winged headboard can be significantly wider than its mattress. For example, the Knightsbridge Winged Divan Storage Bed uses a statement headboard with projecting wings. Its listed sizes refer to the required mattress size, while the overall width is greater because of the headboard wings.
This distinction matters when the bed sits between two walls, beside fitted wardrobes or close to a radiator. Check the headboard height alongside the ceiling, window placement and existing wall décor.
Think about sleeping space and room scale
The largest bed is not always the best bed. A super king can provide generous space, but it may leave little room for storage in a compact bedroom. Conversely, choosing a double for a large main bedroom may make the room feel unfinished and reduce comfort for two sleepers.
For couples, width is particularly important. A double provides a 135 cm-wide sleeping surface shared between two people. A king increases this to 150 cm, while a super king provides 180 cm. The best choice depends on the room and your preferred balance between personal space and available floor area.
Storage bed planning
A storage bed can reduce the need for additional furniture, but the storage mechanism must be considered during room planning. Drawer storage needs clear space beside the bed, while a lift-up base requires room above the mattress to raise the platform. The Knightsbridge is available with optional built-in drawers for bedding, towels and other bedroom essentials. Drawer positions and configurations can vary with the selected bed size.
Do not forget delivery access
A bed can fit comfortably in the bedroom but still be difficult to deliver. Measure the width and height of the front door, internal doors, staircases, landings and any tight turns. Clear ornaments, rugs and small furniture from the route before delivery.
A simple bed-size checklist
Before choosing a bed, record the mattress size you need, the full frame dimensions, the available floor area and the width of the delivery route. Confirm where bedside tables will go, how doors and drawers will open, and whether the headboard will cover any sockets or switches.
For a classic statement look, compare the Kensington Winged Ambassador Bed, Mayfair Vertical Panel Ambassador Bed and Belgravia Deep Button Ambassador Bed. For a practical storage-led design, view the Knightsbridge Winged Divan Storage Bed.
The right bed size is the one that gives you comfortable sleeping space while allowing the rest of the bedroom to work naturally. Measure carefully, allow for the frame rather than only the mattress, and choose a design that suits both your lifestyle and your available room.