When you are planning a bedroom, the mattress size is only the starting point. A bed described as a single, double, king or super king is normally telling you which mattress it is designed to take. The frame itself is usually larger.
That difference matters in a small room. Headboards, side rails, upholstered edges, footboards and storage mechanisms can all add centimetres beyond the mattress.
Common UK mattress sizes
- Single: 90 × 190 cm
- Small double: 120 × 190 cm
- Double: 135 × 190 cm
- King: 150 × 200 cm
- Super king: 180 × 200 cm
These are mattress dimensions, not guaranteed outer dimensions for the bed frame.
Why the frame can be noticeably bigger
A simple metal platform frame may add relatively little around the mattress. An upholstered bed with a padded headboard and deep side rails can add much more. A sleigh-style frame or bed with a substantial footboard can also increase the overall length.
For that reason, compare the product’s overall width, overall length and overall height, not only the mattress size in the title.
Measure the room as the bed will actually be used
Mark the full frame footprint on the floor with masking tape, then check the route around it. A bed can technically fit between two walls while still making a wardrobe, drawer chest or bedroom door awkward to use.
Pay particular attention to:
- wardrobe doors and drawers opening beside the bed;
- bedside-table width and socket position;
- radiators and curtains behind the headboard;
- the space at the foot of the bed;
- access needed for vacuuming or changing bedding.
Storage beds need extra operating space
Ottoman and drawer-storage beds need more than their closed footprint. Side drawers need room to pull out. End-opening ottoman beds need enough access at the foot for you to lift and reach the storage area safely.
Check what is actually included
A bed-frame listing may show a dressed mattress in the photographs even when the mattress is sold separately. Check the product description and the current retailer offer before assuming one is included.
You can compare current options in our beds and bed frames section, where we record outer dimensions separately from the mattress size where the manufacturer provides them.