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King Size Mattress Dimensions
A king size mattress is the size where sharing a bed stops feeling like a nightly negotiation. More and more people across the UK are sizing up, and once you understand how much room a king actually gives you, and what it needs from your bedroom in return, the appeal is easy to see.
If you have ever shared a double and woken up clinging to the edge of the mattress, a king size is usually the point where things finally feel comfortable. Upgrading is not only about width, though. A few details catch buyers out every time, from room clearance and mattress depth to the difference between UK and European king sizes, and whether a zip and link option suits your home better. This guide walks through all of it clearly and honestly, so you know precisely what you are buying before you order.
King Size Mattress Size: The Quick Answer
A standard UK king size mattress measures 150cm wide by 200cm long, which is 5ft by 6ft 6in. Set against a standard UK double, that gives you an extra 15cm across and 10cm in length, working out at roughly 75cm of personal sleeping space each. It is a modest sounding difference on paper that most couples feel from the very first night.
King size mattresses come in every construction you would expect, including pocket sprung, memory foam, hybrid, latex and natural fillings, and in tensions from soft through to extra firm. At Beds Online Shop you will find a full range of Mattresses across every style and budget, all with free delivery to mainland UK.
What Are The Dimensions Of A UK King Size Mattress?
In centimetres a UK king size mattress is 150 by 200. In feet and inches that is 5ft by 6ft 6in, or 59in by 79in if you prefer inches on their own. In metres it is 1.5m by 2.0m, and in millimetres 1500 by 2000. The total sleeping surface comes to around three square metres.
It is worth remembering that mattress size and bed frame size are not the same thing. These measurements cover the mattress only. Bed frames usually run larger, often adding 5 to 10cm on each side depending on the side rails, base and headboard, so always check the full frame dimensions before you order. A king mattress on a Divan Beds base, for example, takes up a very different footprint to the same mattress in an Upholstered Bed Frames design with wide rails.
How Does A King Size Compare To Other UK Mattress Sizes?
UK mattresses follow a clear ladder of widths, all sharing similar lengths until you reach king size and above. A small single is 75cm wide and a single is 90cm, both at 190cm long and intended for one sleeper. A small double is 120cm wide, giving two people around 60cm each, while a standard double is 135cm wide at 190cm long, which is about 67.5cm per person.
King size is the step up that most couples notice. At 150cm wide by 200cm long, it offers around 75cm of space each and adds 10cm of length over a double. Above it sits the European king at 160cm wide, giving roughly 80cm each, then the super king at 180cm wide with about 90cm each. For the largest bedrooms there is the small emperor at 200cm wide, offering around 100cm each, and the emperor at 215cm by 215cm with about 107.5cm each.
How Much Space Does A King Size Give Each Person?
The most useful way to picture a king size is not the total width but the space each sleeper actually gets. On a king that is around 75cm per person, and that figure is where most couples find they can move, turn and settle without setting off a chain reaction on the other side.
On a double, each person has roughly 67.5cm, which is less than a standard single each. It sounds like a small gap, but in practice it is the point where a partner rolling over becomes something you notice. Close that gap and the whole night feels calmer, which is why the upgrade tends to be felt immediately. Step up again to a super king and each person has around 90cm, close to a full single each, with far less awareness of movement during the night.
Length gets talked about far less, yet it matters just as much for the right sleeper. A king is 200cm long against 190cm for a standard double, and that extra 10cm is exactly what taller people need. As a rough rule, a double suits sleepers up to around 5ft 11in, while a king stays comfortable up to around 6ft 3in. If you or your partner are over six foot, the added length alone can change how well you sleep.
What Room Size Do You Need For A King Size Bed?
This is the part most people overlook until the bed arrives. Falling for a king size online is easy, but the reality comes down to floor space. The mattress is 150 by 200cm, yet the room you need is always larger, because you have to walk around the bed, open storage drawers if you have chosen an ottoman or divan, and reach wardrobes without the room feeling boxed in. It is the difference between a bedroom that feels calm and one that feels tight every time you cross it.
A simple clearance rule helps here. Leave at least 60cm of space on each side of the bed you use, and around 90cm on the main side you get in and out of. If the bed does not sit against a wall, aim for around 90cm at the foot as well. As a general guide, a king works best in a room of around 3.5m by 3.5m, which gives you enough room to move around the mattress comfortably without the space feeling squeezed. A double will fit a smaller room of around 3.0m by 3.5m, while a super king really wants around 4.0m by 4.0m before it feels at home.
Before ordering, measure your room at its widest points, note where doors and windows sit, and double check that wardrobe or ensuite doors can open once the bed is in place. A king that fits on paper but leaves no room to move around it will make a bedroom feel smaller, not better.
Mattress Depth And Why It Matters
Width and length get all the attention, but depth deserves just as much thought, for slightly different reasons. Depth is simply how tall the mattress stands from base to sleeping surface, measured in centimetres, and it ranges from around 15cm on basic rolled mattresses up to 35cm or more on premium hand crafted designs with deeper comfort layers.
The first reason depth matters is bedding fit. Fitted sheets and protectors have to accommodate the mattress depth plus any topper. A 30cm mattress with a 5cm topper, for instance, needs sheets rated for at least 35cm. Standard fitted sheets usually stretch to around 25 to 28cm, so check before buying new bedding or a deeper mattress.
The second reason is overall bed height. Your base plus your mattress sets how high the bed sits. A thick mattress on a tall base can make getting in and out harder, while a thin mattress on a low base can leave the bed feeling too low, so think about the combined height rather than the mattress alone.
The third reason is quality. A deeper mattress often means more substantial comfort layers above the spring unit. It is not a perfect measure, since densely packed fillings can sit shallower than lighter ones, but as a general guide anything under 20cm is unlikely to carry a meaningful comfort layer. Mattresses in the 20 to 25cm range tend to be solid mid range options, 25 to 30cm usually signals a premium feel with fuller comfort layers, and anything over 30cm is typically a luxury design with thicker, more detailed construction.
What Is A European King Size Mattress?
This is one of the most common mistakes buyers make, and it is worth getting straight before you order. A European king measures 160cm by 200cm, making it 10cm wider than a UK king while keeping the same length. It is the size used by many European bed manufacturers, so it comes up more often than people expect.
If your frame was made by a European manufacturer, and IKEA frames are the most common example, you will usually need a European king size mattress at 160 by 200cm rather than a UK king at 150 by 200cm. A UK king in a European frame leaves a visible gap of around 10cm, which not only looks off but can affect how the mattress settles over time. For imported American frames you would instead need a US king, sometimes called an Eastern king, which is a different size again at 193cm by 203cm.
If you are unsure which size your frame takes, measure the internal sleeping platform rather than the outer frame. That figure tells you exactly which mattress to buy. At Beds Online Shop we stock both UK and European king sizes across all constructions and tensions, so you have plenty of choice either way, and if you would like a hand deciding, just call us on 07958 930956.
What Is A King Size Zip And Link Mattress?
A zip and link king is two separate mattresses, each 75cm by 200cm, joined to form a full king sleeping surface. Zipped together it looks and feels like one mattress, but each half can be a completely different tension.
For couples with different support needs, it is one of the most practical options going. One person can have a firmer feel for back support while the other chooses something softer to relieve pressure at the hips and shoulders, with no compromise on either side. There is a flexibility that standard king size mattresses cannot match, too, since each half can be unzipped and used on its own if needed, and when replacement time comes you can update one side rather than the whole bed. In everyday use it feels just like a standard king, bedding sizes are identical, and the join is not noticeable during normal sleep.
What Bedding Size Do You Need For A King Size Mattress?
King size bedding is straightforward once you know the numbers. A fitted sheet should be 150 by 200cm with a depth to match your mattress, usually somewhere between 25 and 40cm, and mattresses over 28cm generally need deep pocket sheets. A flat sheet is typically around 240 by 260cm so it tucks under on all sides with a comfortable overhang, and a king size duvet is usually around 225 by 220cm or 230 by 220cm, with that extra width deliberately included so both sleepers stay covered.
Pillowcases are the same as other UK sizes, either standard 50 by 75cm or an Oxford style with a border, since pillow size is not affected by the mattress. A mattress protector should be 150 by 200cm and matched to your mattress depth, sitting directly under the fitted sheet, and if you add a topper it will also be 150 by 200cm and should be factored into the depth when you choose your sheets. Do bear in mind that a European king at 160 by 200cm needs bedding made to match, as standard UK king sheets are usually too narrow, and European ranges can be more limited and a little pricier.
Is A King Size Mattress Right For Your Bedroom?
Does Your Room Have The Space?
Measure first, always. A king works best in around 3.5m by 3.5m, which leaves comfortable room on every side. If your space is tighter, a well made double is often the smarter choice rather than forcing a larger bed into a room that cannot carry it.
Are You Sharing With A Partner?
If so, a king is usually where sharing starts to feel genuinely comfortable. Per person space rises from around 67.5cm on a double to 75cm on a king, which is often the line between noticing every movement and sleeping through the night.
Are You Taller Than 5ft 11in?
A king gives you 200cm of length against 190cm on a double, and that 10cm matters for taller sleepers. As a guide, adding around 20cm to your height helps you find the right length, so anyone around 5ft 9in or above will feel the benefit.
Do You Co-sleep With Children Or Pets?
Here a king is often the sensible minimum. Two adults and a child on a double gets crowded fast, while a king buys everyone some breathing room. If co-sleeping is a regular part of your routine, a super king tends to be the more comfortable long term answer.
King Size Mattress FAQs
What Size Is A UK King Size Mattress?
A standard UK king measures 150cm wide by 200cm long, which is 5ft by 6ft 6in. That is 15cm wider and 10cm longer than a UK double, giving each person around 75cm of personal space.
Is A King Size The Same As A Super King?
No, they are different. A UK king is 150cm wide and a super king is 180cm wide, though both are 200cm long. That extra 30cm lifts each sleeper from around 75cm of space to about 90cm, which feels noticeably more generous. It is a real upgrade, but it needs a larger room of around 4m by 4m and costs more for both the frame and the bedding.
Will A UK King Size Fit A European Or IKEA Frame?
Usually not. European frames are built to European king dimensions of 160cm wide rather than 150cm, so a UK king mattress sits too narrow and leaves a visible gap. For a European frame you will need a European king mattress at 160 by 200cm.
What Room Size Do I Need For A King Size Bed?
As a guide, a king works best in a room of around 3.5m by 3.5m. That allows comfortable clearance around the bed, especially on the sides you use most. In a smaller room, measure carefully and check that doors, wardrobes and walkways still work once the bed is in.
What Is The Difference Between A UK King And A US King?
A US king, sometimes called an Eastern king, measures 193cm by 203cm, making it wider and slightly longer than a UK king. They are entirely different sizes, so mattresses and bedding are not interchangeable. A US frame needs US sized bedding and a US sized mattress.
How Deep Should A King Size Mattress Be?
There is no single ideal, as it depends on the type and quality of the mattress. As a guide, under 20cm tends to be basic, 25 to 30cm usually offers a comfortable mid to premium feel, and over 30cm is often found on higher end mattresses with fuller comfort layers. Always check your fitted sheets suit the depth, particularly if you use a topper.
Can I Use A King Size Mattress On A Double Bed Frame?
No, that is not recommended. A king is both wider and longer than a double frame, so it overhangs the edges. Beyond the look, the mattress is not properly supported, which leads to uneven wear over time. Always match your mattress size to your frame.
Find Your King Size At Beds Online Shop
Ready to make the move to a king size? Explore the full range of Mattresses alongside our Divan Beds, Ottoman Beds and Headboards, all made in the UK with free delivery to mainland UK. If you would like to feel the finish before you buy, order a set of Fabric Swatches, and it is always worth checking the Clearance Section for the current king size offers.
