King Size and Super King Size at a Glance
A UK king size mattress measures 150cm wide by 200cm long. A super king size measures 180cm wide by 200cm long, the same length but 30cm wider, roughly the length of a large office ruler. That extra width is the entire difference in dimensions, and it changes more about the sleeping experience than the numbers alone suggest.
Which Size Is Right for You?
Four things tend to decide this for most people, and it is worth working through them in order rather than picking on space alone.
Room size
A super king needs noticeably more floor space, both for the bed itself and for the clearance around it to open wardrobes and walk comfortably. If you are at all unsure whether your room can take one, our bed size guide for choosing a mattress for your room covers minimum room dimensions for every size.
Delivery access
Tight stairwells, 180 degree turns or narrow doorways can rule out a one piece mattress in either size. This does not rule out a super king altogether though, a zip and link model, built in two halves, gets around most access problems that would stop a one piece mattress going up the stairs.
How you sleep
If you tend to stay near the edge of the mattress and rarely move into the centre, a super king can be the wrong choice rather than the better one. The unused centre of a wide mattress gets little to no use over time, and that can lead to settlement and indents forming where the edges are used constantly and the middle is not. A zip and link super king solves this, since each half can be turned individually, so both sides of each mattress actually get used.
Monthly turning and rotation
Every two sided mattress needs turning and rotating monthly to wear evenly and meet the guarantee terms. A super king can weigh upwards of 80kg once it is packed with natural fibre fillings and calico encased pocket springs, which realistically needs two people to manage.
What is the actual size difference between king and super king?
There is a 30cm difference in width between the two, king size is 150cm wide and super king is 180cm wide. Both are the same length, 200cm. That 30cm gives each sleeper an extra 15cm of personal space on a super king compared to a king size.
Benefits and Drawbacks of a King Size Mattress
- Enough room for two adults to sleep without disturbing each other
- Suits a wide range of sleeping positions
- Fits a wider range of bodyweights and heights than a double
- Can feel a little tight for very active sleepers who move around a lot
- May look out of proportion in a very large bedroom
- Not every bed frame can accommodate a one piece king size
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Benefits and Drawbacks of a Super King Size Mattress
- Enough space to roll over twice before meeting your partner in the middle
- Comfortably suits any sleeping position, side, back or starfish
- Enough room for children or pets to join you without anyone feeling cramped
- Access issues cause more one piece delivery failures than with a king size
- The unused centre of the mattress can form a ridge over time if you both sleep at the edges
- Bedding is bulkier and can be awkward to fit and wash
- Most bedrooms cannot fit a super king with enough space left to move around comfortably