A UK king size mattress measures 150cm wide by 200cm long, which works out at roughly 60 inches by 78 inches. In imperial shorthand it is often described as a 5ft bed, because the width is almost exactly five feet. That makes it 15cm wider and 10cm longer than a standard UK double, and 15cm narrower than a super king.
Those numbers matter more than they first appear. The extra 15cm of width is shared between two sleepers, so each person gains around 7.5cm of personal space. The extra 10cm of length is what most taller sleepers actually notice, because it stops feet reaching the end of the mattress when the duvet is tucked in.
When you are planning a bedroom it helps to have every figure in one place. A UK king size mattress is 150cm by 200cm, or 60in by 78in. Depth varies far more than width and length, and this is the dimension people forget. Pocket sprung and hybrid mattresses commonly sit between 25cm and 32cm deep, while slimmer foam mattresses can be closer to 18cm or 20cm.
Depth changes two practical things. It determines whether your fitted sheets will actually stay on, since many are cut for a 30cm pocket, and it changes the finished height of the bed once the mattress sits on the base. A deep mattress on a tall divan can put the sleeping surface uncomfortably high for shorter household members, so it is worth adding the base height and mattress depth together before you commit.
British bed sizing developed separately from American and European sizing, which is why online guides can be confusing. A US king is wider and shorter than ours, and continental European sizes are usually quoted in even 20cm increments. If you order bedding from an overseas seller, the label may say king but the cut will not match a 150cm by 200cm mattress properly.
The safest approach is to buy your mattress, base and bedding to UK measurements. Every frame in our range of modern king size beds UK is built to the standard 150cm by 200cm mattress footprint, so a UK king mattress drops straight in without gaps at the sides or a lip at the foot.
The mattress is only part of the calculation. A king size bed frame adds to the footprint, and the amount it adds depends on the style. A slim wooden frame might add 5cm to 8cm on each side. An upholstered frame with a padded surround can add 10cm or more per side, and a frame with a deep buttoned headboard can push the total length beyond 210cm.
On top of that, you want walking room. As a working guide, allow at least 60cm of clear floor on any side you need to walk along, and closer to 75cm where a wardrobe door or chest of drawers has to open. Add those margins to a 150cm wide frame and a king size bed with access on both sides needs a room around 2.8m to 3m wide before it feels comfortable rather than crowded.
Many British bedrooms, particularly in Victorian terraces and newer flats, simply do not offer that. In those rooms, pushing one side of the bed against a wall is a reasonable compromise, though it makes changing the bedding harder and the person on the inside has to climb over.
Take three measurements and write them down. First, the full width and length of the room at floor level. Second, the width of the doorway, any turn on the landing, and the stair width if the bed is going upstairs. Third, the position of anything fixed: radiators, skirting depth, window sills, sockets and light switches.
Then mark the footprint out on the floor. Masking tape or a couple of old bedsheets laid down to 150cm by 200cm gives you an honest sense of the space in a way that numbers on paper never will. Walk the route you would take to the wardrobe and the door. If you have to turn sideways, the bed is too big for that layout.
Access matters as much as floor area. A king size mattress cannot be folded, so it has to go up the stairs and round the turn in one piece. Rolled and vacuum packed mattresses solve this neatly, and most bed frames arrive flat packed for exactly the same reason. If your staircase is tight, check the frame headboard dimensions too, since a one piece headboard is often the hardest component to manoeuvre.
A king size fitted sheet is cut to 150cm by 200cm plus the depth pocket. A king size duvet, however, is not 150cm wide. It is usually 225cm by 220cm, deliberately much wider than the mattress so it drapes over both sides. If your duvet keeps sliding off one side, it is often because a double duvet is being used on a king mattress.
Pillows are the other quiet mismatch. A standard UK pillow is 74cm by 48cm, so two of them side by side come to 148cm, which sits almost exactly across a king mattress. That is why king beds tend to look properly balanced with two standard pillows, and why a third pillow has to sit in front rather than alongside.
A king size suits couples who move a lot in their sleep, anyone over about six feet tall, and households where a child or a pet regularly joins in the early hours. It also changes how a large room reads, giving a generous main bedroom a clear focal point rather than a bed that looks lost against the wall.
It is less suitable where floor space is genuinely tight, or where the room has to do more than one job. In a bedroom that also holds a desk or a dressing area, a double often gives a better result overall, because the space you save goes into function you use every day. Our modern double beds UK sale range covers those rooms, and the super king size beds UK selection is there for larger rooms where 150cm still feels narrow.
Storage should be part of the decision too. A king size bed leaves less room for freestanding furniture, so an ottoman lift up base or a divan with drawers can pay for itself in a smaller bedroom. It is also worth pairing the bed with slimmer pieces, and our modern bedside cabinets UK sale range includes narrow designs that fit either side of a 150cm frame without crowding the walkway.
Once the size is settled, the interior matters. Pocket sprung mattresses respond individually across the surface, which suits couples of different weights because movement on one side transfers less. Memory foam contours closely and holds warmth, which some sleepers like and others find too warm. Hybrids combine springs with a foam or latex comfort layer, aiming for support with a softer initial feel.
Firmness is personal rather than universal. Side sleepers usually want more give at the shoulder and hip. Back and front sleepers generally prefer a firmer surface that keeps the spine level. If two people disagree, a king size gives you the option of a zip and link arrangement, where two small single mattresses of differing firmness join to make a king footprint.
Whatever you choose, buy the base and the mattress as a pair where you can. Slat spacing, ventilation and edge support all influence how a mattress performs and how long it lasts. You will find frames, bases and mattresses together at Furniture in Fashion UK, alongside the rest of our bedroom ranges.
The first is measuring the old mattress rather than the room. Old beds shrink at the edges and previous owners fitted odd sizes, so a tape across a tired mattress is not a reliable guide.
The second is forgetting the headboard. A floor standing headboard needs clearance from the skirting board, which quietly adds a few centimetres to the total length. The third is ignoring the door swing. A bedroom door that opens inwards and stops against the bed frame is an irritation you will notice every single day.
No. A UK king is 150cm by 200cm. A US king is wider and shorter, so bedding bought to American sizing will not fit a UK king mattress correctly.
Width. A king is 150cm wide, a super king is 180cm wide. Both are 200cm long, so a super king gives extra shoulder room rather than extra legroom.
As a practical minimum, around 2.8m by 3m if you want walking space on both sides. Rooms smaller than that will still take the bed, but one side may need to sit against a wall.
Only if that frame was built to UK king dimensions. Older and imported frames sometimes use non standard sizes, so measure the internal rails from edge to edge before ordering.
Yes, for proper drape. A king duvet is roughly 225cm by 220cm, considerably wider than the mattress, which is what stops it pulling off one side during the night.
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