A UK king size bed measures 150cm by 200cm, which is 5ft by 6ft 6in. A UK super king measures 180cm by 200cm, or 6ft by 6ft 6in. The length is identical. The only difference is width, and it is 30cm, giving each sleeper an extra 15cm. To use a king comfortably you need a bedroom of roughly 3.2m by 3.6m. For a super king you want at least 3.6m by 3.8m, and ideally more if you want bedside cabinets on both sides. Bedding sizes differ as well, so a change from one to the other means replacing sheets, duvets and mattress protectors.
Put simply: choose a king if the room is a normal main bedroom, and a super king if the room is genuinely large or if two adults sleep differently enough that shared movement disturbs sleep.
Mattress sizes are standardised in the UK, but frame dimensions are not. A king size frame usually measures 160cm to 170cm wide externally once side rails and upholstery are accounted for. A super king frame typically lands between 190cm and 200cm wide.
Length is the same for both at 200cm of mattress, though frames commonly run to 210cm or 220cm depending on the headboard and whether there is a footboard.
Height is a separate decision from size. Both sizes are available as low platform frames, standard height frames and taller storage bases, and that choice affects how large the bed feels far more than the 30cm of width.
One point of confusion worth clearing up: UK and European sizing differ. A European king is not the same as a UK king, and bedding bought abroad frequently does not fit. Always buy bedding labelled for UK sizes.
It is also worth knowing that a super king is sometimes described as a six foot bed and a king as a five foot bed. Both descriptions refer to width only. If a listing quotes a single figure in feet, that figure is almost always the width, and you should still confirm the length separately, because a small number of continental frames run shorter than the UK standard of 200cm.
Work out the floor space before anything else.
For a king size bed, allow the external frame width plus 60cm on each side for access. With a 165cm frame that means a minimum wall to wall width of about 2.85m, though 3.2m gives a comfortable result with bedside cabinets.
For a super king, the same calculation with a 195cm frame requires about 3.15m minimum, and 3.6m for a room that actually feels balanced.
Length needs checking too. Both sizes need roughly 2.2m of wall depth for the bed, plus 70cm to 90cm of clear floor at the foot so you can walk past and open wardrobe doors. A bedroom of 3.6m depth handles this easily. A room of 3m depth will feel tight with either size.
Mark it out with masking tape before deciding. A super king in a room that cannot take it dominates so completely that the rest of the furniture becomes an afterthought.
The 30cm difference is not trivial in practice. On a king, each sleeper has 75cm of width, which is only slightly more than a single bed. On a super king each has 90cm.
That extra room matters most in specific situations. Couples where one person moves frequently during the night benefit, because there is more space before movement is felt. Taller or broader sleepers benefit for obvious reasons. Households where children or a dog regularly join in the morning benefit as well.
Where it matters less is for two people of average build who sleep still. In that case the money is often better spent on a higher quality mattress in a king size than on a super king mattress at the same total budget.
Mattress construction interacts with this. Pocket springs reduce partner disturbance by responding independently, which narrows the practical gap between the two sizes. If you are choosing a king because of space limits but movement is the concern, look at the pocket sprung options in our mattresses UK sale range before ruling out the smaller size.
Moving up a size affects more than the bed itself.
Duvets differ: a UK king duvet is usually 225cm by 220cm, while a super king duvet is around 260cm by 220cm. Fitted sheets, flat sheets, mattress protectors and valances all change with the size.
Super king bedding is stocked less widely than king, which means less choice and generally higher prices. If you already own a full set of king bedding, factor the replacement cost into the decision.
Mattresses in super king cost more than king, and they are heavier to turn. If you rotate a mattress regularly, be aware that a super king mattress is genuinely awkward for one person to handle alone.
Delivery and access should be considered too. A super king mattress is often supplied rolled or vacuum packed, which helps, but the frame components are longer and the headboard panel is wider. Measure stair turns and doorways in older properties.
A king size bed usually leaves room for a pair of bedside cabinets, a chest of drawers and a chair without crowding. It is the size most UK main bedrooms are designed around.
A super king takes that flexibility away in a medium room. You may find you have space for cabinets but not a chest, or that the wardrobe doors no longer clear the bed. In a large room none of this applies, and a super king can actually make a big bedroom feel more resolved by filling the central space properly.
Consider the door position as well. A bed that partially blocks the swing of a bedroom or en suite door is a daily irritation regardless of how comfortable it is.
If storage is your priority, note that a king size storage bed provides a substantial amount of under bed space already, and the extra drawer volume on a super king is rarely the deciding factor. Getting the hanging storage right usually matters more, and our sliding wardrobes UK sale range suits rooms where a hinged door would clash with a large bed.
Scale affects how a bedroom reads. In a room that can take it, a super king with a generous headboard looks intentional and hotel like. The same bed in a modest room looks like furniture that arrived by mistake.
Headboard height should rise with bed width. A wide bed with a short headboard looks unbalanced, so a super king generally wants a headboard of at least 110cm to 130cm.
Bedside furniture needs to keep up too. Narrow cabinets flanking a super king look undersized. Wider low cabinets hold the proportion better.
Rugs follow the same logic. A super king needs a large rug, typically 240cm by 340cm, to sit correctly beneath it. A smaller rug reads as a mat.
You can see both sizes in complete room settings across our king size fabric beds UK sale collection at Furniture in Fashion, which helps with judging proportion before ordering. We offer free delivery to most UK mainland postcodes.
Answer three questions. Does your bedroom measure at least 3.6m by 3.8m? Does either sleeper regularly disturb the other, or is one of you over six feet tall? Are you willing to replace your bedding and accept a smaller choice of sets?
Three yes answers point to a super king. Two suggest a king with a better mattress. One suggests a king without hesitation.
The most common regret we hear is not from people who chose a king. It is from people who fitted a super king into a room that could hold it but not comfortably accommodate it, and then found the room difficult to use.
Width only. A king is 150cm by 200cm and a super king is 180cm by 200cm. Both are the same length, so the difference is 30cm across, or 15cm per sleeper.
At least 3.6m by 3.8m for a comfortable result with bedside cabinets and clear walking space. The absolute minimum is around 3.15m wide, which leaves little room for anything else.
No. The duvet and fitted sheet dimensions differ significantly, and king bedding will not cover a super king mattress properly.
It is if the room is large enough and one of you moves during the night or needs the length and width. If the room is average, a king size with a better quality pocket sprung mattress is usually the stronger choice.
The components are wider and the mattress is heavier, so check stair turns, landings and doorways first. Assembly is similar in method but benefits from two people.
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