King vs Super King Bed: Dimensions, Room Size and Which to Choose

Quick Answer: Standard UK king-size mattress dimensions are 200 x 150cm, while a super king measures 200 x 180cm, giving you an extra 30cm of width without increasing the length.

Choosing between a king and super king bed might seem straightforward, but several factors are worth considering before deciding which size works best for your bedroom. While both options offer a generous sleeping surface, the width difference can noticeably affect how your room looks, feels, and functions.

It's not simply about choosing the biggest mattress available, either. You'll need to consider your bedroom dimensions, furniture placement, and how much space you'd prefer around the bed.

In this guide, we'll explain the differences between king and super king beds, including their measurements, room requirements, and bedding sizes, to help you make a more informed decision.

King and Super King Sizes at a Glance

Before exploring the differences in more detail, it's useful to compare the measurements side by side.

Both mattresses share the same length and depth; the main difference is their width.

These measurements refer specifically to True Rest mattresses, not the external dimensions of a bed frame.

If you're considering other options, see our Mattress Size Guide for more mattress information and sizing guidance.

King Size Bed Dimensions in cm and Inches

A standard UK king-size mattress measures 200cm long and 150cm wide, or about 79 inches by 59 inches. The width is also equivalent to five feet, which is why king-size mattresses are commonly called a 5ft mattress.

At two metres long, a king mattress matches a super king's length, making width the deciding factor between the two options.

When measuring your bedroom, remember that mattress dimensions show only the space the sleeping surface takes up. Your chosen bed frame may extend beyond these measurements, especially if it has a substantial headboard, upholstered edges, or additional detailing.

It's therefore worth measuring the complete bed rather than relying solely on the mattress size.

Super King Size Bed Dimensions in cm and Inches

A standard UK super king mattress measures 200cm long and 180cm wide, or about 79 inches by 71 inches. That's a width of six feet, making it 30cm wider than a standard king mattress.

Although 30cm might not sound like much, it becomes more noticeable when you're planning a bedroom layout. For example, if your bed sits between two bedside tables, a wider mattress could reduce the space on either side. Similarly, a wider bed might affect how comfortably you can move around other furniture.

The important thing to remember is that a super king doesn't provide additional length. You're choosing a wider sleeping surface, rather than a longer mattress.

What Is the Difference Between King and Super King?

The biggest difference between a king and super king mattress is the width.

A king measures 150cm across, while a super king measures 180cm, giving you an extra 30cm of sleeping surface. Both mattresses are 200cm long, so they take up the same space from the head of the bed to the foot.

The extra width also means a super king occupies more floor space overall. A king mattress covers approximately 3 square metres, compared with 3.6 square metres for a super king. That's an additional 0.6 square metres to accommodate within your bedroom.

Neither option is automatically better. The right choice depends on how much space you have available and whether you'd prefer a wider mattress or more open floor space around your furniture.

Mattress Size vs Bed Frame Size

One detail people often overlook when choosing a mattress is the difference between mattress measurements and bed frame dimensions. Although UK mattress sizes are standardised, bed frames don't always match those external measurements.

For example, an upholstered frame with padded sides may take up more floor space than a simpler design. Likewise, a frame with an extended headboard or decorative features may require more space. This means knowing your mattress measures 200 x 180cm doesn't guarantee a super king bed frame will fit that space exactly.

Before purchasing, check the manufacturer's full external measurements, including the overall width and length. Also check whether the frame is designed specifically for UK mattress sizes, as international measurements can differ.

Taking these extra measurements now can help prevent problems when arranging your bedroom later.

How Much Room Do You Need?

Knowing your mattress dimensions is one thing, but understanding how they translate into your bedroom is just as important.

As a general planning guide, leave enough space to walk comfortably around the accessible sides of the bed and to open wardrobe doors and drawers fully. The amount you need depends on your layout and furniture. For example, a bedroom with fitted wardrobes and minimal furniture might accommodate a larger mattress more comfortably than a similarly sized room containing several freestanding pieces.

• When planning your space, consider the following:
• Walking space: Ensure enough room to move around the bed comfortably.
• Wardrobes and drawers: Check that doors and drawers can open fully without hitting the frame.
• Bedside furniture: Allow enough space for tables, lamps and other essentials.
• Bedroom doors: Consider the direction doors open and whether furniture could obstruct them.
• Overall layout: Think about whether the larger bed will make the room feel unnecessarily crowded.

Rather than choosing a mattress based on bedroom dimensions alone, mark out the proposed bed size on the floor with masking tape.

This gives a clearer picture of how much space the bed will take up and whether the remaining layout feels practical.

Will It Get Into Your Room?

Another important consideration is getting your new mattress into the bedroom.

This is especially relevant when choosing larger mattresses, as doorways, narrow hallways, and staircases can make moving furniture difficult. Fortunately, True Rest mattresses arrive in compact boxes, making them easier to manoeuvre than a mattress delivered at its full dimensions.

Both the king and super king mattresses are packaged in a box measuring approximately 400 x 400 x 1090mm, or 40 x 40 x 109cm.

Despite the difference in mattress width, the packaging dimensions remain the same.

However, it's still important to measure your access routes before ordering. Consider narrow corners, door frames, staircase turns and any obstacles between your entrance and bedroom. You'll also need enough clear floor space to unpack the mattress and allow it to expand.

Checking these details beforehand can make the delivery and setup process considerably easier.

Which Size Should You Choose?

Ultimately, deciding between a king and super king mattress comes down to your available space, bedroom layout and personal preference. Both share the same length, so the main question is whether the extra 30cm of width is worth the added floor space.

Choose a King Size Bed If...

A king-size mattress may be a better option if you want a generous sleeping surface without using as much bedroom space. It's especially worth considering if your bedroom has limited clearance around the bed or if you want more room for furniture.

A king also makes sense if you're happy with a 150cm-wide mattress and don't think the extra width would improve your bedroom setup.

Choose a Super King Size Bed If...

Consider a super king mattress if your bedroom comfortably fits the extra width and you'd prefer a more expansive sleeping surface. It can also work well in rooms where the bed is meant to be a prominent feature, as long as the wider dimensions don't compromise movement or access to furniture.

Before you decide, compare both options with your actual room measurements rather than assuming the larger size will automatically be better. The best choice is ultimately the mattress that provides your preferred amount of sleeping space while still allowing your bedroom to function comfortably.

Bedding Sizes for King and Super King Beds

Choosing the correct mattress size is only part of the process. You'll also need bedding that fits properly.

Standard UK king fitted sheets are designed for mattresses measuring 150 x 200cm, while super king fitted sheets accommodate mattresses measuring 180 x 200cm.

Duvets vary in size because they're designed to extend beyond the mattress edges.

A typical UK king duvet measures approximately 225 x 220cm, while a super king duvet measures 260 x 220cm. Some manufacturers use slightly different measurements, so always check the product specifications.

Mattress depth also matters when choosing fitted sheets.

True Rest mattresses are 25cm deep, so you'll need sheets with pockets deep enough to fit securely around the mattress.

If you're moving from a king to a super king, remember that your existing fitted sheets won't accommodate the additional width.

Include the cost of replacement bedding in your budget, especially if you're changing several sets at once.

Conclusion

When comparing king and super king beds, the biggest consideration is whether you have enough room for the additional width. Both mattresses measure 200cm long, but a super king adds 30cm of sleeping space. While that can make a noticeable difference, consider how the larger mattress will fit alongside your existing furniture.

Measure your bedroom carefully, check the external dimensions of your preferred bed frame, and make sure you have enough space to move around comfortably.

For more information, explore the True Rest Mattress Size Guide or take a closer look at our King Size Mattress and Super King Mattress.

Our super king mattress is currently listed as coming soon, so you can explore its specifications and check back later for availability.

Frequently Asked Questions (FAQs)

How wide is a king size bed?

A standard UK king-size mattress measures 150cm wide, equivalent to about 59 inches, or five feet. It is 200cm long, although the external dimensions of a king-size bed frame may be larger.

How much bigger is a super king than a king?

A super king mattress is 30cm wider than a king, measuring 180cm compared with 150cm. Both mattresses are 200cm long, meaning the additional space comes entirely from the width.

Is a king size mattress 5ft?

Yes, a standard UK king size mattress is five feet wide, measuring 150 x 200cm. The five-foot measurement refers to its width, not its length.

Can a king mattress fit a super king frame?

A king mattress is narrower than the super king frame it's designed for. This could leave gaps around the mattress and prevent it from fitting securely. It's best to match your mattress to the frame's intended size.

What is the standard UK king size bed frame size?

There isn't one universal external measurement for UK king size bed frames. Although they're designed to accommodate a 150 x 200cm mattress, overall dimensions vary by manufacturer and design. Always check the frame's specifications before purchasing.