Single vs Double vs King: Mattress Size Guide UK

Introduction: Why Mattress Size Matters More Than You Think

Choosing the right mattress size is one of the most important decisions you'll make when buying a new bed, yet it's often overlooked in favour of focusing solely on comfort and support. The truth is, even the most luxurious, supportive mattress won't deliver quality sleep if it's the wrong size for your needs, your bedroom, or your sleeping arrangements.

A mattress that's too small can leave you feeling cramped, disturb your partner's sleep, and prevent you from stretching out comfortably. One that's too large can overwhelm your bedroom, make movement difficult, and create practical challenges with bedding and furniture arrangement. Getting the size right is fundamental to creating a sleep environment that promotes rest, comfort, and wellbeing.

This comprehensive guide to UK mattress sizes will help you navigate the options available, understand the differences between single, double, king, and other sizes, and make an informed decision based on your specific circumstances. Whether you're furnishing a child's room, upgrading from a single to a double, or finally investing in that king-size luxury you've been dreaming of, you'll find everything you need to choose the perfect size.

Understanding UK Mattress Sizes: The Complete Breakdown

UK mattress sizes follow standard dimensions that differ from those used in other countries, particularly the United States. Understanding these standard sizes is the first step in making the right choice.

Small Single (75cm x 190cm - 2'6" x 6'3")

The small single is the most compact standard mattress size available in the UK. At 75cm wide and 190cm long, it's designed for tight spaces and specific use cases.

This size is ideal for young children transitioning from a cot, guest rooms with very limited space, caravans, motorhomes, and compact living situations, or bunk beds and cabin beds where space is at a premium. The small single provides a proper mattress sleeping surface in situations where a larger size simply won't fit.

However, the small single is quite restrictive for adults and even older children. Most people will find it too narrow for comfortable long-term use, and taller individuals (over 6 feet) will find the length insufficient. It's best viewed as a space-saving solution rather than an ideal sleeping surface for regular adult use.

Single (90cm x 190cm - 3' x 6'3")

The standard single mattress is 90cm wide and 190cm long, making it the traditional choice for children's bedrooms and single adult sleepers in smaller spaces.

Single mattresses work well for children's rooms, teenagers' bedrooms, guest rooms, student accommodation, and single adults in compact flats or bedsits. The single provides adequate space for one person to sleep comfortably, with room to turn over and change positions during the night.

At 90cm wide, a single mattress offers reasonable comfort for most individuals sleeping alone, though larger adults or those who move frequently during sleep may find it somewhat restrictive. The 190cm length accommodates most people up to about 6 feet tall, though taller individuals should consider a long single (see below).

Single mattresses are also the most affordable option and easiest to move, making them practical for situations where budget or logistics are concerns.

Long Single (90cm x 200cm - 3' x 6'6")

The long single maintains the 90cm width of a standard single but extends the length to 200cm, providing an extra 10cm of legroom.

This size is perfect for taller teenagers and adults who need single-bed accommodation, guest rooms where visitors might be tall, and situations where width is limited but length is available. The long single solves the common problem of feet hanging off the end of a standard single mattress.

However, long single mattresses and bedding can be harder to find than standard singles, and they may cost slightly more. They also require more floor space lengthwise, which may not work in all room configurations.

Small Double (120cm x 190cm - 4' x 6'3")

The small double, sometimes called a "three-quarter bed," is 120cm wide and 190cm long. It sits between a single and a standard double, offering a compromise for those who need more width than a single but can't accommodate a full double.

Small doubles are suitable for single adults who want more sleeping space than a single provides, couples in very compact bedrooms who can't fit a standard double, guest rooms where you want to accommodate couples but space is limited, and teenagers who want more room than a single.

At 120cm wide, a small double provides comfortable space for one person with room to spread out, but it's quite tight for two adults. Couples may find themselves disturbing each other during the night, and there's limited personal space. For long-term couple use, a standard double or larger is generally recommended.

Like long singles, small double bedding can be harder to source than more common sizes, and the size doesn't offer significant advantages over a standard double for most situations.

Double (135cm x 190cm - 4'6" x 6'3")

The standard double mattress is 135cm wide and 190cm long, making it one of the most popular sizes in the UK. It's the traditional choice for couples and the minimum size most sleep experts recommend for two adults sharing a bed.

Double mattresses are ideal for couples in average-sized bedrooms, single adults who want plenty of space, master bedrooms in flats and smaller homes, and guest rooms intended to accommodate couples. The double provides a good balance of sleeping space and bedroom footprint.

At 135cm wide, a double mattress gives each person approximately 67.5cm of personal space—less than a single mattress. This means couples will be closer together and more likely to disturb each other during the night compared to larger sizes. For couples who are both average height and build, and who don't move excessively during sleep, a double can work well. However, larger individuals, restless sleepers, or those who value personal space may find it restrictive.

The 190cm length is adequate for most people up to about 6 feet tall, but taller individuals may find their feet hanging off the end or need to sleep diagonally.

King Size (150cm x 200cm - 5' x 6'6")

The king size mattress is 150cm wide and 200cm long, offering significantly more space than a double. It's increasingly popular as the preferred choice for couples who have the bedroom space to accommodate it.

King size mattresses are perfect for couples who want comfortable personal space, master bedrooms with adequate floor space, taller individuals (the extra 10cm length makes a real difference), couples with children or pets who sometimes join them in bed, and anyone who values spacious, luxurious sleep.

At 150cm wide, a king size gives each person 75cm of personal space—more than a single mattress. This extra width significantly reduces sleep disturbance between partners and allows for more comfortable movement during the night. The 200cm length accommodates people up to about 6'6\" tall comfortably.

The main consideration with king size mattresses is space. You need a bedroom large enough to accommodate the mattress while leaving adequate room for movement, furniture, and access. A king size bed can overwhelm a small bedroom, making it feel cramped rather than luxurious.

Super King Size (180cm x 200cm - 6' x 6'6")

The super king is the largest standard UK mattress size at 180cm wide and 200cm long. It offers the ultimate in sleeping space and luxury.

Super king mattresses are ideal for couples who want maximum personal space and luxury, larger individuals who need extra width, master bedrooms in larger homes, people who share their bed with children or pets, and those who simply want the most spacious sleep experience possible.

At 180cm wide, a super king provides each person with 90cm of personal space—equivalent to a full single mattress each. This virtually eliminates sleep disturbance between partners and allows for complete freedom of movement. It's the closest you can get to having separate beds while still sharing one mattress.

The super king requires a large bedroom—ideally at least 3.6m x 4m to avoid the room feeling cramped. You'll also need to consider doorways and staircases when delivering the mattress, as the size can make access challenging in some properties. Bedding for super king mattresses is readily available but more expensive than smaller sizes.

Emperor and Other Specialty Sizes

Beyond standard sizes, some manufacturers offer emperor (200cm x 200cm) and even larger custom sizes. These are designed for those who want the absolute maximum sleeping space or have specific requirements.

These specialty sizes require very large bedrooms, custom bedding (which can be expensive and harder to source), and careful consideration of access and delivery. They're typically chosen by those with spacious master suites who prioritize sleep luxury above all else.

How to Choose the Right Mattress Size for Your Needs

Understanding the dimensions is one thing, but how do you determine which size is right for you? Several factors should influence your decision.

Number of Sleepers

The most obvious consideration is whether you sleep alone or with a partner. For single sleepers, a single or small double typically provides adequate space, though larger individuals or those who move frequently during sleep may prefer a double for extra room. For couples, a double is the minimum recommended size, with king or super king offering significantly better sleep quality due to reduced disturbance and increased personal space.

If you frequently share your bed with children or pets, factor this into your size decision. What works for two adults alone may feel cramped when a toddler or dog joins you at 3 AM.

Your Height and Build

Your physical size significantly affects which mattress dimensions will be comfortable. As a general rule, your mattress should be at least 10-15cm longer than the tallest person sleeping in it. This means individuals over 6 feet tall should seriously consider long single, king, or super king options with 200cm length.

Width requirements also increase with body size. Larger individuals need more personal space to sleep comfortably. A person of average build might be fine with 67.5cm of width (half a double), but someone with a broader frame will feel cramped in the same space.

Sleep Style and Movement

How you sleep affects your space requirements. If you sleep relatively still in one position all night, you can manage with less space. If you're an active sleeper who changes positions frequently, spreads out, or moves around, you'll benefit from extra width and length.

Couples should consider both partners' sleep styles. If one person is a restless sleeper, a larger mattress reduces the likelihood of disturbing their partner. Motion isolation features in the mattress itself help, but more space is the most effective solution.

Bedroom Dimensions

Your bedroom size is a crucial practical constraint. A mattress should fit in your room while leaving adequate space for movement, furniture, and access.

As a general guideline, leave at least 60-70cm of clear space on each side of the bed for easy access and movement. You should be able to walk around the bed comfortably and open wardrobes or drawers without difficulty. Measure your bedroom carefully before committing to a size, and consider creating a floor plan or using tape to mark out the mattress dimensions to visualize how it will fit.

Don't forget to measure doorways, staircases, and hallways to ensure you can actually get the mattress into your bedroom. Larger mattresses can be challenging to maneuver through tight spaces, and some properties simply can't accommodate super king mattresses due to access limitations.

Existing Furniture and Bed Frame

If you're replacing a mattress but keeping your existing bed frame, you're constrained to the same size unless you're also replacing the frame. Ensure you know your current mattress size before shopping.

If you're buying both a new mattress and frame, you have more flexibility, but remember that larger bed frames take up more floor space and may require rearranging other bedroom furniture.

Budget Considerations

Larger mattresses cost more than smaller ones, both for the mattress itself and for bedding. A super king mattress might cost 50-100% more than a double in the same range, and bedding costs increase proportionally.

However, don't let budget alone drive you to a size that's too small for your needs. Poor sleep due to an inadequate mattress size affects your health, wellbeing, and quality of life. It's better to invest in the right size in a mid-range quality than to buy a premium mattress in a size that's too small.

Future Considerations

Think about your future needs, not just current circumstances. If you're single now but likely to have a partner in the future, a double or king might be a better investment than a single. If you're furnishing a child's room, consider how long the mattress will need to last—a teenager will quickly outgrow a small single.

A quality mattress should last 7-10 years, so consider where you'll be and what your needs might be over that timeframe.

Practical Considerations: Beyond the Dimensions

Choosing the right size involves more than just measuring and comparing dimensions. Several practical factors affect your decision and experience.

Bedding Availability and Cost

Standard sizes (single, double, king, super king) have widely available bedding in all price ranges and styles. You'll find countless options for sheets, duvet covers, and fitted sheets in these sizes.

Less common sizes (small single, long single, small double) have more limited bedding options. You may find fewer choices, higher prices, and difficulty finding specific styles or materials. If you choose one of these sizes, factor in the potential inconvenience and cost of sourcing bedding.

Delivery and Access

Larger mattresses can be challenging to deliver and install, particularly in properties with narrow staircases, tight corners, or small doorways. Before ordering a king or super king mattress, measure your access route carefully.

Standard doorways in the UK are typically 76-80cm wide, which is fine for mattresses up to king size when angled, but super king mattresses (180cm wide) can be problematic. Some mattresses come rolled and compressed for easier delivery, which can help with access issues.

If access is a concern, discuss it with the retailer before purchasing. Some offer delivery services that include professional installation and can advise on whether your chosen size will fit through your property's access points.

Mattress Weight and Handling

Larger mattresses are heavier and more difficult to move, rotate, or flip. A single mattress might weigh 15-20kg and be manageable for one person, while a super king can weigh 50-80kg and require two people to handle safely.

Consider this if you like to rotate your mattress regularly (recommended for even wear), if you move house frequently, or if you need to access storage under the bed. Some mattress types (like pocket sprung) are heavier than others (like foam), so factor in both size and construction.

Room Proportions and Aesthetics

Beyond practical fit, consider how the mattress size affects your room's aesthetics and proportions. A super king bed can look magnificent in a large master suite but overwhelming in a modest bedroom. Conversely, a small double in a spacious room can look lost and underwhelming.

The bed is typically the focal point of a bedroom, so its size should be proportionate to the room. As a rough guide, the bed should occupy about one-third to one-half of the floor space in a bedroom, leaving adequate room for circulation and other furniture.

Common Mattress Size Mistakes to Avoid

Understanding common pitfalls can help you make a better decision and avoid regret.

Assuming Bigger Is Always Better

While a larger mattress often provides better sleep, it's not universally true. A super king in a small bedroom can make the space feel cramped and claustrophobic, actually reducing sleep quality. The right size balances sleeping space with room proportions and practical considerations.

Not Measuring Properly

Many people eyeball their bedroom space or rely on memory when choosing a mattress size. This often leads to surprises when the mattress arrives. Always measure your bedroom, doorways, and access routes carefully before ordering. Use tape or cardboard to mark out the mattress dimensions on your floor to visualize the space it will occupy.

Forgetting About Bedding Costs

The mattress price is just the beginning. Larger sizes require more expensive bedding, and you'll need multiple sets of sheets, duvet covers, and fitted sheets. Factor these ongoing costs into your budget when choosing a size.

Not Considering Partner Needs

If you're choosing a mattress for shared use, both partners' needs matter. Don't let one person's preference for a smaller size (perhaps due to cost or aesthetics) override the other's need for more space. Poor sleep affects both partners and can strain relationships. It's worth investing in adequate space for both people to sleep well.

Choosing Based on Current Furniture

Some people choose a mattress size based on their existing bed frame or bedroom furniture arrangement. While practical considerations matter, don't let an old bed frame prevent you from getting the size you actually need. Bed frames can be replaced; your sleep quality affects your health every single night.

Ignoring Height Requirements

Tall individuals often focus on width and forget about length. If you're over 6 feet tall, the extra 10cm length of a king or super king (200cm vs 190cm) makes a significant difference in comfort. Don't compromise on length—it's just as important as width.

Mattress Sizes for Different Life Stages and Situations

Your ideal mattress size often depends on your life stage and specific circumstances.

Children and Teenagers

For young children transitioning from a cot, a small single or standard single is typically appropriate. These sizes fit well in children's bedrooms and are proportionate to a child's size.

As children grow into teenagers, consider their height and how long you want the mattress to last. A tall teenager might need a long single or even a small double. If the mattress needs to last through university years, investing in a size with room to grow makes sense.

Young Adults and Students

Students and young adults in shared accommodation or small flats often need to balance space constraints with comfort. A single or small double typically works well, providing adequate sleeping space without overwhelming limited bedroom space.

If budget allows and space permits, a double offers more comfort and flexibility—it can accommodate overnight guests and provides more personal space.

Couples and Families

For couples, a double is the minimum recommended size, but king or super king significantly improves sleep quality. If you have children who sometimes join you in bed, or if you have pets, factor this into your size decision. What feels spacious for two adults becomes cramped with additions.

Many couples find that upgrading from a double to a king is one of the best investments they make in their relationship and sleep quality. The reduction in sleep disturbance and increase in personal space can be transformative.

Guest Rooms

Guest room mattress size depends on who you typically host and how often. If you frequently have couples staying, a double or king is appropriate. If guests are usually single friends or family members, a single or small double works well and leaves more room for other furniture or uses when the room isn't occupied by guests.

Some people choose a small double for guest rooms as a compromise—comfortable for one person, adequate for a couple in a pinch, but not taking up as much space as a full double.

Older Adults

As we age, comfort and ease of access become increasingly important. Older adults might benefit from a larger mattress that makes changing positions easier and reduces pressure points. However, very large mattresses can be difficult to make and maintain, and getting in and out of bed from the side might be easier with a smaller width.

Consider mobility, whether one or two people will use the bed, and practical factors like the ability to change bedding when choosing a size for older adults.

Maximizing Your Space: Tips for Different Mattress Sizes

Once you've chosen your mattress size, these tips can help you make the most of it.

Making a Small Mattress Work

If you're constrained to a smaller mattress than you'd ideally like, several strategies can help maximize comfort. Choose a mattress with excellent edge support to maximize usable sleeping surface. Consider a mattress topper to enhance comfort within the size you have. Use quality pillows to support your sleeping position and reduce the need to spread out. Keep the area around your bed clear to create a sense of spaciousness even if the mattress itself is compact.

Our mattress toppers collection offers options that can significantly enhance the comfort of any size mattress, helping you make the most of the space you have.

Optimizing a Large Mattress

If you've invested in a king or super king, make sure you're getting the full benefit. Use quality, well-fitted bedding that doesn't bunch or slip—this is especially important on larger mattresses. Consider zoned mattresses or toppers that provide different support levels for different body areas. Rotate your mattress regularly to ensure even wear across the larger surface. Invest in a quality bed frame with good support across the entire mattress area.

Room Layout Considerations

The way you position your mattress in the room affects both aesthetics and functionality. In most bedrooms, centering the bed on the longest wall creates the best balance and symmetry. Ensure you have adequate access on both sides—at least 60cm is ideal for making the bed and getting in and out comfortably. Leave space at the foot of the bed for a chest, bench, or clear walking path. Consider the position of windows, radiators, and doors when planning your layout.

UK vs International Mattress Sizes

If you're moving to or from the UK, or shopping internationally, be aware that mattress sizes differ between countries.

UK vs US Sizes

US mattress sizes don't directly correspond to UK sizes. A US "full" (also called "double") is 135cm x 190cm—the same as a UK double. However, a US "queen" (152cm x 203cm) falls between a UK king and super king, and a US "king" (193cm x 203cm) is wider than a UK super king but not as wide as a UK emperor.

If you're bringing a mattress from the US or buying US bedding, check dimensions carefully rather than assuming size names are equivalent.

European Sizes

European mattress sizes are typically measured in centimeters and may differ slightly from UK standards. Common European sizes include 90x200cm (similar to UK long single), 140x200cm (between UK small double and double), and 160x200cm (between UK king and super king).

If you're buying a European mattress or bedding, verify the exact dimensions to ensure compatibility with your bed frame and existing bedding.

Our Mattress Collections: Quality in Every Size

Understanding mattress sizes helps you make an informed decision, but quality matters just as much as dimensions. Our carefully curated mattress collections offer exceptional comfort and support across all standard UK sizes.

PureCloud Mattresses

Our PureCloud Mattresses collection features advanced comfort technology available in all standard UK sizes from single to super king. Whether you're furnishing a child's room with a single or creating a luxurious master suite with a super king, PureCloud mattresses deliver consistent quality and performance scaled to your chosen size.

PureSleep Mattresses

The PureSleep Mattresses range offers reliable, supportive sleep solutions in sizes to suit every need. From compact singles perfect for guest rooms to spacious super kings for couples who value personal space, PureSleep mattresses provide the support and comfort you need in the size that fits your life.

Utopia Mattresses

For those seeking premium quality and luxury comfort, our Utopia Mattresses collection delivers exceptional sleep experiences in all standard sizes. Whether you choose a double for a cozy master bedroom or a super king for ultimate luxury, Utopia mattresses represent the pinnacle of comfort and craftsmanship.

Customization Options

If you've chosen your ideal size but want to fine-tune the comfort level, explore our mattress toppers collection. Available in all standard UK sizes, these toppers allow you to customize your sleep surface to your exact preferences, ensuring you get the perfect combination of size and comfort.

Conclusion: Choosing Your Perfect Size

Selecting the right mattress size is a decision that affects your sleep quality, bedroom aesthetics, and daily wellbeing for years to come. While it might seem like a simple choice, the considerations are numerous: your physical size, sleeping arrangements, bedroom dimensions, budget, and lifestyle all play important roles.

The key is to balance these factors thoughtfully. Don't compromise on size if it means sacrificing sleep quality—your health and wellbeing depend on quality rest. At the same time, be realistic about your space constraints and practical considerations. The perfect mattress size is the one that provides adequate sleeping space while fitting comfortably in your bedroom and your life.

For single sleepers, don't automatically default to a single mattress. If you have the space and budget, a small double or even a double provides luxurious room to spread out and can accommodate overnight guests. For couples, seriously consider upgrading to a king if your bedroom can accommodate it—the improvement in sleep quality and reduction in partner disturbance is often transformative. The investment in a larger size typically pays dividends in better sleep and relationship harmony.

Remember that your mattress is one of the most important purchases you'll make for your home. You spend roughly a third of your life sleeping, and quality sleep affects everything from your physical health to your mental clarity, emotional resilience, and daily performance. Choosing the right size is just as important as choosing the right type, firmness, and quality level.

Take the time to measure carefully, consider your needs honestly, and choose the size that will serve you best for years to come. Whether you opt for a compact single, a versatile double, a spacious king, or a luxurious super king, make sure it's the right choice for your unique circumstances.

Your perfect night's sleep is waiting—in exactly the right size.