UK Bed Sizes Explained: Mattress Dimensions Guide
UK bed sizes follow a fixed set of standard dimensions, from a single at 90 x 190cm up to a super king at 180 x 200cm, and the size you need depends on your height, who you share with, and the room it has to fit in.
The single most important thing to understand is that a double mattress (135 x 190cm) gives each sleeper only 67.5cm of width, which is less than a single, so most couples sleep far better on a king or super king. People with stiff necks and aching hips often never consider that their bed is simply too small for the way they sleep, so getting the size right matters before you spend anything on the mattress itself.
๐ Key Takeaways
- Standard UK sizes are fixed - single 90 x 190cm, small double 120 x 190cm, double 135 x 190cm, king 150 x 200cm, super king 180 x 200cm
- A double is cramped for two adults - each person gets 67.5cm of width, so couples who can fit a king (150cm wide) almost always sleep better on one
- Height matters more than people think - if you're over 6ft, a 190cm-long mattress leaves your feet hanging off the end, so look for a 200cm option
- UK and EU sizes differ - many continental mattresses are 200cm long while standard UK singles, small doubles and doubles are 190cm, so check cm before you buy
๐ Suggested Reading: How to Choose a Mattress ยท Best Mattresses UK 2026
UK Bed and Mattress Sizes at a Glance
The dimensions below are the UK standard set by the National Bed Federation, and every British mattress maker builds to them. If a retailer quotes something different, it's either a continental size or a bespoke product, so treat the name as a guide rather than a guarantee.
| Size | Dimensions | Imperial | Best for |
|---|---|---|---|
| Single | 90 x 190cm | 3'0" x 6'3" | One adult or child |
| Small double | 120 x 190cm | 4'0" x 6'3" | Compact guest rooms |
| Double | 135 x 190cm | 4'6" x 6'3" | One tall adult, or a couple who like to snuggle |
| King | 150 x 200cm | 5'0" x 6'6" | The standard couples size |
| Super king | 180 x 200cm | 6'0" x 6'6" | Couples who want real space |
| Emperor | 200 x 200cm | 6'6" x 6'6" | Very large rooms |
The Which? bed and mattress size guide lists the same dimensions and adds a useful check: the most popular sizes in the UK are the double and the king, which is why shops stock the most choice in those two. A mattress like the Emma Premium comes in every standard size, and it's worth confirming the exact cm when you order so you don't end up with a continental oddity.
Why Size Matters More Than You Think
In twenty years of physiotherapy, the patients with the most persistent morning stiffness are often the ones sleeping on a bed that doesn't fit them. Three problems show up again and again. First, length: a 190cm mattress leaves anyone over about 6ft with their feet hanging past the end, which pushes the ankles and knees into awkward angles all night.
Second, width: in a double, two sleepers are close enough that the heavier person's movements rock the mattress, and partner disturbance is one of the most common, and most fixable, causes of fragmented sleep. Third, there's the comfort-zone problem, where one person is forced into a fixed position because there's nowhere else to go, which is how you wake up with a dead arm or a twisted hip.
The NHS sleep guidance is clear that consistent, undisturbed sleep is the goal, and a bed that gives you enough length and width is part of the setup. A simple test: lie on your back and slide down until your head rests flat on the pillow, then check your feet. If they touch the end of the bed, the mattress is too short for you.
How to Pick the Right Size for You
Work in this order: length first, then width, then the room. For length, add roughly 15cm to your height as a rule of thumb, because you need room to stretch without your feet hitting the end. A 6ft person should be on a 200cm-long mattress, which means a king, super king or emperor, since standard singles, small doubles and doubles are all 190cm long.
For width, think about how you actually sleep. A side sleeper curls up and uses less width than a starfish sprawler, but if you share the bed, the couple standard is a king. Each person gets 75cm on a king versus 67.5cm on a double, and the extra 7.5cm per side is exactly what stops elbows meeting in the middle.
If you both toss and turn, or one of you is a restless sleeper, a Simba Hybrid in king size pairs the width with motion isolation so you feel less of each other's movements, and a Tempur mattress does the same job if you prefer a firmer, moulded feel.
Finally, measure the room before you commit. You want at least 60cm of walkway around the bed, and if the room is tight, a small double at 120 x 190cm is a sensible compromise for a guest room. For a main bedroom where two adults sleep, a king-size OTTY hybrid is the smallest size I'd recommend, and a super king if the room allows it.
UK vs European vs US Sizes
This is where most people get caught out, because the names look familiar but the numbers differ. Standard UK singles, small doubles and doubles are 190cm long, while many European mattresses are 200cm long, and European doubles come in several widths. The US "queen" and "king" don't match UK sizes at all, so a mattress bought from an American site won't fit a UK bed frame or UK bedding.
Always buy by the centimetres, not by the label, and check the product listing against the table above.
Bedding That Actually Fits
Your mattress size dictates your bedding sizes, and getting that wrong wastes money. A fitted sheet for a double won't stay on a king mattress, and a king duvet on a double bed drapes over the sides while leaving the foot exposed. As a rule of thumb: a single duvet is 135 x 200cm, a double is 200 x 200cm, a king is 225 x 220cm, and a super king is 260 x 220cm.
Our best bed sheets guide and best duvet covers guide both list the exact sizes each product comes in, so you can match them to your new mattress without guessing.
Common Size Mistakes to Avoid
The four mistakes I see most: buying a "queen" from a foreign brand, sizing up the duvet but not the mattress, forgetting that divans and frames add a few centimetres, and skipping the small double entirely when a guest room could use one. The duvet trick is worth repeating: many couples buy a king duvet to stop the duvet tug-of-war, and that works fine on a double bed as long as the overhang doesn't reach the floor.
When you buy a new mattress, measure the existing frame or divan base first, because some frames only take specific sizes, and check our best divan beds guide if you're replacing the whole setup.
Frequently Asked Questions
What are the standard UK bed sizes in cm?
The standard UK bed sizes are: single 90 x 190cm, small double 120 x 190cm, double 135 x 190cm, king 150 x 200cm, super king 180 x 200cm, and emperor 200 x 200cm. These are set by the National Bed Federation and followed by UK mattress makers.
What size is a small double bed?
A small double bed is 120 x 190cm (4'0" x 6'3"). It gives each sleeper roughly 60cm of width, which is tighter than a single, so it works best as a compromise for a guest room or a compact main bedroom rather than for two adults who want comfortable space.
What size bed do two adults need?
A double bed gives each person only 67.5cm of width, less than a single mattress. Most couples sleep measurably better on a king (150 x 200cm), which gives each person 75cm, or a super king (180 x 200cm), which gives 90cm each.
Are UK and European bed sizes the same?
No. Many European mattresses are 200cm long while standard UK single, small double and double mattresses are 190cm long. A continental single is usually 90 x 200cm and continental double sizes vary, so check the exact dimensions rather than relying on the name.
What duvet size fits a double bed?
A standard UK double duvet is 200 x 200cm, and it drapes evenly over a 135 x 190cm mattress. Many couples size up to a king duvet (225 x 220cm) on a double bed to avoid tug-of-war at night.
The Bottom Line
Start with your height and your sleeping partner, then check the room. If you're over 6ft, you need a 200cm-long mattress. If you share the bed, a king is the smallest size most couples should consider, and a super king if space allows. Match your bedding to the mattress you end up with, and check the centimetres on every product page, because the size names are only a shortcut.
For the full mattress decision, our mattress buying guide covers firmness, materials and budget, and the best mattresses UK 2026 roundup compares the top models in every size.
For more sleep guides, visit SleepReview
