dimensions of king size mattress

What Are the Dimensions of King Size Mattress?

The standard dimensions of king size mattress in Australia are approximately 183 cm wide × 203 cm long. Some manufacturers specify the width as 183.5 cm, so it is always worth checking the exact mattress specifications before purchasing a bed frame, fitted sheet or other bedding.

In millimetres, the commonly quoted dimensions are 1,830 × 2,030 mm. In imperial measurements, this is approximately 72 × 80 inches.

An Australian King mattress is 30 cm wider than a standard Queen mattress, while both are generally 203 cm long. A Super King is wider again, measuring approximately 203 × 203 cm.

Quick Facts

• Standard Australian King: approximately 183 × 203 cm
• Alternative manufacturer measurement: approximately 183.5 × 203 cm
• Millimetres: approximately 1,830 × 2,030 mm
• Imperial: approximately 72 × 80 inches
• Queen: approximately 153 × 203 cm
• Super King: approximately 203 × 203 cm
• Mattress size: Does not include the bed frame or headboard
• Best suited to: Couples, larger bedrooms and sleepers wanting extra personal space

Why Are King Size Mattresses So Popular?

The main reason Australians choose a King mattress is the generous width.

At approximately 183 cm wide, a King provides considerably more personal sleeping space than a Queen while retaining the same approximate 203 cm length. This makes it particularly appealing to couples who want additional room to move during the night.

A King can also be useful for households where children or pets occasionally share the bed.

The additional width does, however, require careful bedroom planning. The mattress itself occupies more than 3.7 square metres, before allowing for the bed frame, bedside tables and walking space.

Australian King Mattress Dimensions Explained

Width

The standard Australian King mattress width is approximately 183 cm.

Some manufacturers quote 183.5 cm, so small differences between brands are possible.

Length

A standard Australian King mattress is approximately 203 cm long.

This makes it 15 cm longer than an Australian Double and the same general length as Queen, King Single and Super King mattresses.

Thickness

Unlike width and length, mattress thickness is not standardised to one fixed measurement.

Depending on construction, a King mattress might be relatively low-profile or considerably deeper. Pillow-top, plush, hybrid and premium mattresses can all have different heights.

This matters when selecting fitted sheets and bed frames.

Dimensions of King Size Mattress Compared With Other Australian Sizes

The exact dimensions can vary slightly between manufacturers, so these measurements should be treated as a useful Australian sizing guide rather than a substitute for the product specifications.

King vs Queen Mattress

A Queen mattress is approximately 153 × 203 cm, while a King is approximately 183 × 203 cm.

The main difference is width.

A King provides around 30 cm of additional width, giving couples noticeably more room to spread out.

Both sizes are approximately the same length, so upgrading from Queen to King primarily changes the amount of side-to-side sleeping space.

Choose a King if:

• You want more personal sleeping space
• Two adults regularly share the bed
• Children or pets occasionally join you
• Your bedroom has enough floor space
• You prefer a generous, luxurious bedroom proportion

Choose a Queen if:

• Your bedroom is more compact
• You want to maximise surrounding floor space
• You prefer a smaller overall furniture footprint
• A Queen already provides sufficient sleeping space

King vs Super King

An Australian Super King mattress is approximately 203 × 203 cm.

Compared with a standard King, the Super King adds around 20 cm of width while retaining the same 203 cm length.

This makes Super King particularly appealing in large master bedrooms where generous proportions are important.

Before choosing one, however, consider the complete footprint of the bed frame and the amount of circulation space available around it.

How to Choose a Bed Frame for a King Mattress

One of the most important points about the dimensions of king size mattress is that the mattress measurement is not the same as the external measurement of the bed.

A King mattress may measure approximately 183 × 203 cm, but the completed bed can be wider or longer because of:

• Headboards
• Side rails
• Footboards
• Upholstered surrounds
• Storage compartments
• Decorative frames
• Bed legs and structural components

Always check the external dimensions of the bed frame, rather than assuming it will occupy exactly 183 × 203 cm.

How Much Bedroom Space Does a King Need?

A King mattress itself is approximately 183 × 203 cm, but comfortable bedroom planning requires additional space around it.

Allow room for:

• Walking around both sides
• Opening wardrobes
• Opening bedroom doors
• Bedside tables
• Drawers and storage
• Cleaning around the bed
• Making the bed comfortably

A room can physically accommodate a King mattress but still feel cramped once the frame and other furniture are introduced.

For a polished interior, the goal is not simply to make the bed fit. It should have enough breathing room to feel proportionate.

Benefits & Use Cases

More Personal Space

The additional width makes a King especially comfortable for couples.

Comfortable for Families

The larger sleeping surface provides more room when children occasionally climb into bed.

Suitable for Master Bedrooms

The generous dimensions create a strong focal point in a spacious main bedroom.

Luxurious Proportions

A King mattress can give a bedroom a more substantial, hotel-inspired appearance.

Better for Active Sleepers

Extra width can be helpful for people who move frequently during sleep.

Flexible Bedding Styling

A King mattress works beautifully with layered quilts, doonas, blankets, throws and decorative cushions.

Suitable for Split Bases

Some King configurations use two separate bases beneath one overall King mattress size, which can make handling and movement easier.

House of Isabella Recommendations

When shopping around the dimensions of king size mattress, begin with the mattress measurement and then consider the complete bedroom.

A King bed works beautifully as the centrepiece of a spacious bedroom, particularly when paired with a substantial bedhead, coordinated bedside tables and layered bedding.

For a sophisticated Australian interior, consider natural textures, warm neutrals and carefully proportioned accessories. A generous quilt or doona, textured throw and a selection of cushions can soften the scale of a King bed without making it feel overcrowded.

House of Isabella Australia offers distinctive homewares and furniture, a large in-stock catalogue, fast delivery Australia-wide, East and West Coast warehouses and Australian-based customer care.

Buy Now, Pay Later options including Afterpay and Zip can also make larger bedroom updates easier to plan.

Collections such as Florabelle Collection, Zaffero, Emac & Lawton, Gallery Home, Café Lighting & Living and OneWorld Collection can provide contextual inspiration when coordinating bedside furniture, lighting and decorative pieces.

Trends for 2025 in Australia

Generous Layered Bedding

King beds provide plenty of space for layered bedding, creating the relaxed luxury associated with boutique hotels.

Warm Neutral Palettes

Cream, oatmeal, beige, taupe, warm white and earthy shades continue to create calm bedroom environments.

Statement Bedheads

Large upholstered and timber bedheads can balance the generous width of a King mattress and create a strong visual focal point.

Natural Textures

Linen-look fabrics, timber, woven details and tactile throws add warmth without overwhelming the room.

Soft Curves

Rounded bedside tables, curved bedheads and organic accessories can soften the strong rectangular proportions of a King bed.

Integrated Storage

Storage beds are increasingly useful for keeping spare bedding and seasonal items organised without requiring additional furniture.

Boutique-Hotel Styling

Layered bedding, symmetrical bedside tables, statement lighting and restrained decorative accessories create a polished bedroom atmosphere.

Styling Advice for a King Bed

Centre the Bed

Position the bed so the room feels balanced rather than simply pushing it against the largest available wall.

Add Proportionate Bedside Tables

A King bed can make very small bedside tables look visually lost. Choose pieces that feel appropriately substantial without obstructing movement.

Layer Your Bedding

Begin with fitted bedding, add a King-sized quilt or doona, then introduce a coverlet, blanket or throw for additional texture.

Use Decorative Cushions Carefully

A few larger cushions can create depth, while too many can make the bed difficult to use.

Consider the Bedhead

A wide upholstered or timber bedhead can reinforce the scale of the King mattress and create a sophisticated focal point.

Add Balanced Lighting

Matching bedside lamps create symmetry, while sculptural pendant lights or wall-mounted lighting can provide a more contemporary approach.

Mattress Dimensions vs Bed Frame Dimensions

This distinction is particularly important when planning a bedroom.

Mattress dimensions describe the sleeping surface itself.

Bed frame dimensions describe the complete external footprint of the furniture.

For example, a King mattress may be approximately 183 × 203 cm, while the finished bed frame could be larger depending on its construction.

If you are working with a tight room, always measure the complete bed rather than relying only on the mattress size.

Common Questions

What are the dimensions of a King size mattress in Australia?

A standard Australian King mattress is approximately 183 × 203 cm, although some manufacturers specify approximately 183.5 × 203 cm.

How big is a King mattress in inches?

An Australian King is approximately 72 × 80 inches.

Is an Australian King the same as a US King?

No. An Australian King is approximately 183 × 203 cm, while a US King is wider at approximately 193 × 203 cm.

Is a King mattress bigger than a Queen?

Yes. An Australian King is approximately 30 cm wider than a Queen, while both are generally around 203 cm long.

What size is a Super King mattress in Australia?

An Australian Super King is approximately 203 × 203 cm, making it around 20 cm wider than a standard King.

Will every King fitted sheet fit every King mattress?

Not necessarily. Width and length are generally standardised, but mattress depth can vary considerably. Always check the fitted sheet's depth and the mattress manufacturer's specifications.

The Finishing Touch

Understanding the dimensions of king size mattress makes planning a bedroom much easier.

For most Australian homes, the key measurement to remember is approximately 183 × 203 cm. However, always check the exact manufacturer's dimensions, particularly when buying a bed frame, fitted sheets or mattress accessories.

A King mattress offers generous sleeping space and can become an impressive centrepiece in a well-proportioned bedroom. Give it enough surrounding space, balance its scale with substantial furniture and finish the look with layered, tactile bedding.

The result is a bedroom that feels spacious, comfortable and beautifully considered.

Related Glossary Terms

• Width of King Size Bed Australia
• Mattress King Size Measurements
• Frame for King Size Mattress
• Bed Width Queen
• Dimensions of Beds
• King Size Bedding

Disclaimer

Brand and collection names mentioned in this glossary are included purely for descriptive and contextual purposes. House of Isabella Australia is not affiliated with, endorsed by, or associated with the brands mentioned, and all trademarks remain the property of their respective owners.