A UK super king mattress measures 180 cm x 200 cm, or about 6 ft x 6 ft 6 in. If you're trying to work out what size is super king size mattress before buying a new bed, that's the number you need to match to your frame, bedding, and room layout.
People often make a mistake: they see “super king”, assume bigger is always better, order the mattress, and only then realise the room feels squeezed, the fitted sheets don't fit properly, or the bed frame came from a catalogue using a different sizing system. A super king can be an excellent choice for couples, restless sleepers, and anyone who wants proper sleeping space, but only if every part of the setup matches.
Table of Contents
- What Are the Dimensions of a Super King Mattress
- Super King vs Other UK Mattress Sizes
- Will a Super King Mattress Fit in Your Bedroom
- UK vs International Sizing A Common Pitfall
- Finding Your Perfect Super King Mattress with REM-Fit
- Your Final Checklist Before Buying a Super King Bed
What Are the Dimensions of a Super King Mattress
A UK super king mattress measures 180 cm x 200 cm, or roughly 6 ft x 6 ft 6 in. Those dimensions matter more than the label, because "super king" only helps if your bed base, fitted sheets, protector, and frame are built for the same footprint.
The key detail is the width. A super king gives you 180 cm across, while a standard UK king gives you 150 cm x 200 cm. The length stays the same at 200 cm, so this size does not give taller sleepers extra legroom. It gives couples more room side to side, which is usually what they were trying to fix in the first place.
That extra width is where its true value sits. It suits couples who disturb each other, anyone who sprawls out, and households where a child or pet occasionally ends up in the bed. For a solo sleeper in a smaller room, the gain is often less useful than expected.
Why the measurement matters before you buy
A common sizing mistake is focusing on the mattress name instead of the exact footprint. "Super king" sounds clear enough until you start matching it with a frame, deep fitted sheet, valance, or mattress protector and realise one item is listed in UK sizing and another is not.
Practical buying starts with dimensions, not marketing names. If you want a visual sense of room layout before you commit, a guide to choosing the right bed size can help you judge how the bed will sit alongside wardrobes, bedside tables, and walking space. It also helps to compare the full range in a UK mattress sizes guide so you can see whether the jump from king to super king solves the problem you have.
Practical rule: Buy for the exact dimensions you need, and check bedding compatibility before you order anything.
Super King vs Other UK Mattress Sizes
A super king only makes sense when compared to the sizes commonly considered. In UK terms, that usually means single, double, king, and super king.
UK standard mattress size comparison
| UK Size | Dimensions (cm) | Dimensions (ft & in) |
|---|---|---|
| Single | 90 cm x 190 cm | Approx. 3 ft x 6 ft 3 in |
| Double | 137 cm x 190 cm | Approx. 4 ft 6 in x 6 ft 3 in |
| King | 150 cm x 200 cm | Approx. 5 ft x 6 ft 6 in |
| Super King | 180 cm x 200 cm | Approx. 6 ft x 6 ft 6 in |
The super king sits clearly above the double and single categories in UK sizing guides, which is one reason it tends to suit master bedrooms rather than tighter spaces. The jump from king to super king is about width, not length, so it feels different rather than just bigger.
What the extra width changes in real life
The biggest difference is sleep disturbance. When two people share a standard double, movement travels quickly across the surface because there just isn't much spare room. A king improves that. A super king gives each sleeper noticeably more personal space, which matters if one of you turns often, sleeps hot, or likes to spread out.
That extra width also gives edge support more room to matter. On a wider hybrid, you're less likely to feel pushed towards the middle if the support layers and perimeter hold up properly. If you're comparing support styles before sizing up, this guide to a king size hybrid mattress in the UK is useful because it highlights how mattress construction affects the feel of shared sleep space.
For shoppers who want a firmer sleep surface, the Rejuvenated REM-Fit 500 Ortho Hybrid Mattress is described as having Firm Support (9/10), deep, breathable memory foam and 2000 firm pocket springs, plus edge-to-edge stability and motion isolation. Those are the kinds of features that matter more when you move into wider shared-bed sizes.
A larger mattress doesn't fix a poor support system. It only gives bad support more room to annoy you.
Will a Super King Mattress Fit in Your Bedroom
A super king can fit on paper and still be the wrong choice in practice. That's the mistake. People measure wall to wall, confirm the mattress dimensions, and stop there. Then the room loses flow, bedside access becomes awkward, and wardrobe doors start clipping corners.
Measure the room like a buyer, not a browser
Start with the usable floor area, not the estate-agent photo. Measure the actual wall lengths, then mark out the mattress footprint on the floor with tape or cardboard. Do the same for bedside tables if you'll use them.
Then check the routes around it:
- Walking space: You need enough room to get in and out comfortably without turning sideways.
- Furniture clearance: Wardrobes, drawers, and en-suites need to open without striking the bed.
- Visual bulk: A big bed with a deep frame and oversized headboard can dominate a room even if the mattress technically fits.
- Delivery path: The mattress may arrive compressed, but divan bases, headboards, and frames still need to get upstairs.
If you're ordering a full bed setup, it also helps to review a size reference like the REM-Fit size chart so the mattress, base, and accessories are all checked against the same standard.
What usually causes fitting problems
The room isn't always the issue. Sometimes it's access. Tight stairs, loft conversions, narrow landings, and bulky bed components cause more stress than the mattress itself. If you're moving house or replacing a large frame, this guide on what to expect from movers with furniture gives a useful overview of the disassembly and reassembly questions worth asking before delivery day.
Another common problem is forgetting the extra pieces around the bed. People account for the mattress but not the frame rails, deep headboard, ottoman base, or chunky bedside cabinets. The result is a room that feels organised in your head and cramped in real life.
Measure the route to the bedroom before you order the bed. Returns caused by access problems are avoidable and annoying.
UK vs International Sizing A Common Pitfall
This is the part too many mattress guides skip. The name super king is not globally consistent, and that catches people out when they buy from mixed UK, EU, or US catalogues.
Why the name creates expensive mistakes
UK sources define a super king as 180 cm x 200 cm, while other markets use different dimensions or different naming conventions entirely, as explained in this super king bed size guide. That same guide also notes that a UK super king is 30 cm wider than a UK king, which is useful in Britain but doesn't help much if the retailer's frame or bedding is listed to another country's standard.
The problem isn't just mattresses. It shows up in:
- Bed frames bought from international furniture brands
- Fitted sheets labelled “king” or “super king” without centimetre dimensions
- Hotel specs that use local naming conventions
- Imported protectors and toppers that sound right but don't match the footprint
What to check before you order anything
Ignore the label first. Check the centimetres. That applies to the mattress, the frame, the slat base, the fitted sheet depth, the protector, and the duvet cover range if the retailer ties bedding bundles to mattress size names.
If a product page says only “king” or “super king” and doesn't give exact dimensions, that's not enough information. A UK shopper should treat the measurement as the actual specification and the name as shorthand.
That's especially important if you're mixing suppliers. One brand may use UK bed terminology properly, another may translate from an EU or US catalogue, and the mismatch only becomes obvious when the corners won't pull down or the frame leaves overhang.
Check centimetres first, product names second. That single habit prevents most sizing mistakes.
Finding Your Perfect Super King Mattress with REM-Fit
Once you know the size is right, the next question is which kind of mattress suits that footprint. Bigger doesn't automatically mean better sleep. In a super king, construction matters more because the surface area is larger, the sleep positions vary more, and partner disturbance becomes more noticeable if the support layers aren't balanced properly.
Match the feel to the size
For super king buyers, hybrid construction usually makes more sense than an all-foam mattress if you want a blend of airflow, pressure relief, and stable support across a wider bed. Pocket springs help the mattress respond locally rather than as one large slab, and open, breathable comfort layers can be more practical for couples who sleep at different temperatures.
At REM-Fit, the super king range includes options such as the 3000 Supreme, 4000 Ortho Lux Elite, and 5000 Lux Elite, which you can browse in the super king mattress collection. The names matter because older model references still confuse shoppers. If you're comparing product lists, the former 400 is now the 3000 Supreme, the 500 Ortho is now the 4000 Ortho Lux Elite, and the 600 Lux is now the 5000 Lux Elite.
Different sleepers should read those model names as feel cues, not just marketing labels:
- 3000 Supreme: a sensible place to start if you want a balanced hybrid feel.
- 4000 Ortho Lux Elite: the firmer direction for sleepers who prioritise support and alignment.
- 5000 Lux Elite: better suited to shoppers who want a more cushioned, higher-spec hybrid finish.
Don't ignore pillows bedding and base compatibility
The mattress isn't the whole sleep setup. A super king bed often changes what works overhead and underneath too. If you sleep hot, a cooling pillow matters more on a larger bed because the mattress can improve airflow but won't fix a heat-trapping pillow. The same goes for protectors and deep fitted sheets. If the depth or corner shape is wrong, the bed never feels tidy and the cover can shift through the night.
Base choice matters as well. A mattress may match a frame by width and length but still feel wrong if the support platform is too rigid, too flexible, or built for another market's dimensions. Divan bases are often simpler for size matching. Slatted frames need more careful checking.
From a practical sleep point of view, a super king works best when the whole system lines up. Mattress feel, pillow temperature control, sheet depth, protector fit, and base compatibility all need to agree. If one part is off, the size advantage gets wasted.
Your Final Checklist Before Buying a Super King Bed
Before you press buy, stop and check the parts people usually skip. A super king is a worthwhile upgrade when the room, frame, bedding, and mattress type all line up. When they don't, it becomes an expensive way to make your bedroom less usable.
Use this checklist:
- Confirm the actual mattress size: For a UK super king, you're looking for 180 cm x 200 cm, not just the words “super king”.
- Measure the bedroom properly: Check wall lengths, walking space, furniture swing, and where bedside tables will sit.
- Measure the access route: Stairs, hallways, corners, and door openings matter as much as the room itself.
- Match every accessory to UK sizing: Frame, fitted sheets, protector, topper, and valance all need the same footprint.
- Check the support style you want: Hybrid builds tend to suit couples well because they combine contouring comfort with a more stable base.
- Think about heat as well as support: If you sleep warm, don't spend all your attention on the mattress and ignore breathable pillows and bedding.
- Review delivery and assembly needs: If the bed frame is bulky or the property has awkward access, it helps to understand how TLC Moving & Storage's furniture disassembly process works so you know what kind of handling may be needed.
- Compare against a proper size guide: This guide to choosing the right mattress size is a useful final sense check before ordering.
If you're still asking what size is super king size mattress, the answer is simple. Buying it properly is the part that needs discipline.
If you want a UK super king mattress from a sleep brand focused on hybrid support, cooling comfort, and practical delivery options, take a look at REM-Fit. You can compare super king models, check the current naming across the range, and see which hybrid build suits your sleep style before you commit.
