Mattress Thickness Australia: Is a Thicker Mattress Really Better?

A tall, substantial mattress can look impressive on a showroom floor. Put it next to a slimmer mattress and it is easy to assume the thicker one contains more support, more comfort and ultimately more value.

But mattress thickness does not work quite like that.

A thicker mattress is not automatically a better mattress.

Thickness matters because a mattress needs enough room for its comfort and support systems to do their jobs. But the total number of centimetres tells you very little about the quality of those materials, how they are arranged, how supportive the mattress will feel or whether it is right for you.

Two mattresses can both be 30 cm thick and feel completely different.

So, if you are comparing mattress thickness in Australia, the better question is not simply:

What Does Mattress Thickness Actually Mean?

Mattress thickness, sometimes called mattress depth or mattress height, is simply the measurement from the bottom of the mattress to its highest point.

Depending on the mattress, that total depth may include:

This is why the number on the specification sheet needs some context.

Imagine two mattresses that are both 30 cm deep.

One might use much of that space for a substantial support system combined with responsive comfort materials. Another might achieve the same overall height with a very deep pillow top and a different internal construction.

They have the same thickness on paper, but they may feel nothing alike when you lie on them.

Is There a Standard Mattress Thickness in Australia?

There is no single mattress thickness that every Australian adult mattress needs to be.

You will find everyday mattresses available in a broad range of depths because mattresses are built for different purposes, materials, comfort levels and bed setups.

Rather than treating one measurement as the Australian “ideal”, it is more useful to look at whether the mattress has enough depth for its particular construction to provide the intended comfort and support.

A relatively slim mattress is not automatically poor quality.

Likewise, a very deep mattress is not automatically premium quality.

Does a Thicker Mattress Mean a Better Mattress?

Not necessarily.

This is probably the biggest misconception around mattress thickness.

Extra depth can be useful when it allows a manufacturer to incorporate more substantial comfort layers, different support components or a more complex mattress construction.

But simply adding centimetres does not guarantee better:

The quality and purpose of those layers matter more than the headline measurement.

Think about it another way.

A thick jacket is not automatically warmer than every thinner jacket. What it is made from and how it is constructed matter.

Mattresses are similar.

Where Are the Extra Centimetres Actually Going?

This is one of the most useful questions you can ask when comparing mattresses.

Extra mattress depth may come from several places.

This is why comparing mattresses only by thickness can be misleading.

Two 30 cm Mattresses Can Be Very Different Inside

Consider this simplified example.

Both could end up around the same overall height.

That does not mean they will offer the same firmness, support, pressure response or feel.

Does Mattress Thickness Affect Comfort?

It can, but not on its own.

A mattress needs enough usable comfort material to accommodate the body appropriately. For example, a side sleeper may appreciate a mattress construction that gives the shoulder and hip enough room to settle comfortably into the surface.

But that does not mean every side sleeper needs a mattress of a particular total thickness.

A deeper mattress could still feel very firm if its upper layers are designed that way. A slimmer mattress could provide excellent cushioning if its materials and construction are appropriate.

That is a much more useful comparison.

Does Mattress Thickness Affect Support?

Again, construction matters more than the total measurement.

Support comes from the way the mattress responds to your body and manages weight across its structure. Different mattresses achieve this in different ways.

A thicker mattress has more physical space available for layers, but that does not guarantee that those layers are better designed or better suited to you.

When comparing support, look beyond depth and consider:

If you can, lie on the mattress rather than judging it from specifications alone.

What About Mattress Thickness for Heavier Sleepers?

Body weight is relevant when choosing a mattress, but a simple rule such as “heavier sleepers need a 35 cm mattress” can be misleading.

A larger or heavier sleeper may need a mattress that provides enough usable comfort depth while maintaining appropriate support underneath.

That depends on more than total height.

It can include the resilience of the comfort materials, the design of the support system, edge stability and how the mattress performs under load.

So if you are concerned about whether a mattress is suitable for your body weight, ask about the actual construction and any relevant manufacturer guidance rather than relying on thickness alone.

When Can a Mattress Actually Be Too Thick?

This is where mattress thickness becomes much more practical.

Even if you love the feel of a deep mattress, you still need to consider how it will work with the rest of your bed.

1. Your Finished Bed May Become Too High

The number that matters in your bedroom is not just mattress thickness.

A 35 cm mattress on a low base might be perfectly practical.

Put the same mattress on a tall ensemble or bed frame and the finished bed could feel considerably higher.

That matters when you are getting in and out of bed.

Research involving older adults has found that bed height can influence the effort involved in moving from sitting to standing, which reinforces why the whole bed setup should be considered rather than mattress depth in isolation. You can view the published study on bed height and sit-to-stand movement.

There is no single ideal finished bed height for everyone.

Your height, mobility and personal preferences all matter.

A simple test is to sit on the edge of the complete bed. Can you place your feet comfortably on the floor? Can you get on and off without feeling as though you are climbing up onto the mattress or dropping down from it?

If mobility or transfers are a concern, suitability should be assessed more carefully for the individual.

2. A Thick Mattress Can Hide Your Bedhead

This is easy to overlook.

A mattress might look perfectly proportioned on its own, but once it is sitting on a tall base, it can cover more of the bedhead than you expected.

Before buying an especially deep mattress, measure:

1. the height of your bed frame or base
2. the mattress depth
3. how much of the bedhead will remain visible

This is particularly worth checking if your bed frame has a low decorative bedhead.

3. Your Fitted Sheets May Not Fit Properly

Mattress width and length are not the only measurements that matter when buying sheets.

The fitted-sheet skirt needs enough depth to wrap around the mattress.

If you have a particularly thick mattress, especially with a mattress topper on top, standard fitted sheets may not reach far enough underneath.

Before buying new bedding, check both:

• mattress depth
• fitted-sheet skirt or pocket depth

Allow enough room for the sheet to fit securely around the mattress rather than matching the measurements exactly.

4. Storage and Gas-Lift Beds Need More Than a Thickness Check

If you use a gas-lift or storage bed, mattress weight can matter as much as mattress thickness.

A thick mattress containing substantial layers and support components may also be relatively heavy.

Check the specifications supplied with your bed frame and lifting mechanism before changing mattresses.

5. Adjustable Beds Require Mattress Compatibility

If you have an adjustable bed, do not select a mattress on thickness alone.

An adjustable mattress needs to be designed to move appropriately with the base as the head or foot section changes position.

Construction, flexibility and compatibility are more important than simply choosing a thin or thick mattress.

Always confirm that the particular mattress is suitable for use with your adjustable base.

Mattress Thickness Matters for Top Bunk Beds

There is one situation where mattress height deserves particularly careful attention: the upper level of a bunk bed or other elevated bed.

Australian product safety guidance tells consumers to check the maximum mattress height marked on the upper bunk. The purpose is to maintain enough effective guardrail height once the mattress is installed. You can read the Australian bunk-bed safety guidance for more information.

Australia and New Zealand also have the revised AS/NZS 4220:2026 Bunk beds and other elevated beds standard covering safety requirements including design, construction and product markings. Standards Australia provides further information about the updated bunk-bed standard.

So you should not simply buy a thick mattress for an upper bunk because it appears more comfortable.

This is a good example of why “thicker is better” can sometimes be exactly the wrong way to choose.

What Should You Ask Instead of “How Thick Is It?”

Mattress thickness is worth knowing, but it should be the beginning of the conversation rather than the end.

When comparing mattresses, ask:

What Is Creating the Mattress Height?

Is the additional depth coming from comfort layers, quilting, latex, foam, springs or another part of the construction?

What Type of Support System Does It Use?

The support system can tell you far more about how the mattress is intended to perform than its overall height.

What Are the Comfort Layers Made From?

Two equally thick comfort sections can perform very differently depending on their materials and construction.

How Does It Feel Under My Body?

Specifications cannot completely replace lying on the mattress.

Try different constructions and firmness levels if you can.

Will It Work With My Existing Bed Base?

Check support requirements, dimensions and compatibility. If you are unsure about the foundation underneath your new mattress, our guide to bed bases can help you understand the role of the support underneath.

What Will the Total Bed Height Be?

Measure the complete setup, not just the mattress.

Will My Existing Sheets Fit?

Check fitted-sheet skirt depth, especially if you use a topper.

Is There a Maximum Mattress Height?

This is particularly important for upper bunks and some specialised bed setups.

A Simple Mattress Thickness Checklist

Before deciding that a thicker mattress is better value, work through these questions:

If you can answer those questions, the total mattress thickness becomes much more meaningful.

Expert Insight: What Really Matters Inside Those Extra Centimetres?

Why Comparing Mattress Construction in Person Can Help

Mattress specifications are useful, but numbers on a product page cannot tell you exactly how a mattress will feel.

This is particularly true with thickness.

You might expect the thickest mattress in a range to feel the softest or most luxurious, then discover that another construction suits you better.

Simply The Best offers a range of mattress constructions using combinations of pocket springs, latex, memory foam and resilient comfort layers. The Superior Sleep Indulgence construction, for example, combines multiple comfort materials with pocket spring support rather than relying on mattress height as a single indicator of performance.

If you are in Perth, comparing different mattress constructions at the Malaga factory showroom gives you the opportunity to feel what those differences mean rather than choosing purely from measurements.

You can also compare the Simply The Best mattress range before visiting.

Frequently Asked Questions About Mattress Thickness

Is a 25 cm Mattress Thick Enough?

It can be.

A 25 cm mattress should not be judged as good or bad from thickness alone. Look at its internal construction, support system, comfort layers and whether it suits your body and bed setup.

Is a 30 cm Mattress Better Than a 25 cm Mattress?

Not automatically.

The extra 5 cm might contribute useful comfort or support materials, but the measurement alone does not tell you that.

Compare what is inside each mattress and how each one feels.

Are Thicker Mattresses More Comfortable?

Some are, but thickness does not guarantee comfort.

Comfort depends on factors such as firmness, comfort-layer materials, responsiveness, support and how the mattress interacts with your body.

Are Thicker Mattresses Softer?

No.

A thick mattress can be firm, medium or plush. Likewise, a slimmer mattress can feel soft or firm depending on how it is constructed.

Thickness and firmness are different characteristics.

Does a Thicker Mattress Last Longer?

Not necessarily.

More material does not automatically mean better material.

Durability depends on the construction, quality of components, how the mattress is used, whether it is properly supported and other factors.

Does Mattress Thickness Affect Fitted Sheets?

Yes, it can.

Deep mattresses may require deeper fitted-sheet skirts. Include any mattress topper when working out the total depth your sheet needs to cover.

Can a Mattress Be Too Thick for an Adjustable Bed?

Thickness itself is only part of the issue.

The mattress needs to be compatible with the adjustable base and flexible enough for the intended articulation. Always confirm compatibility for the particular mattress and base.

How Thick Should a Bunk-Bed Mattress Be in Australia?

For an upper bunk, follow the maximum mattress height marked on the bunk bed rather than relying on a generic thickness recommendation. Australian product safety guidance specifically highlights this because mattress height affects the effective height of the guardrail.

Should I Choose the Thickest Mattress I Can Afford?

No.

Start with how the mattress is constructed, how it feels, the support you need and whether it suits your bed setup. Thickness should then be considered as one part of the overall decision.

So, Does Mattress Thickness Really Matter?

Yes, but probably not in the way many shoppers expect.

Mattress thickness tells you how tall the mattress is.

It does not, by itself, tell you how comfortable, supportive, durable or suitable that mattress will be.

A thicker mattress may contain additional comfort or support materials that genuinely improve its construction. Or it may simply be a different design.

The useful question is therefore not:

“Which mattress is thickest?”

It is:

“What are those centimetres actually doing?”

Look inside the construction. Consider the comfort and support systems. Measure the complete bed height. Check your base, sheets and any compatibility requirements.

And most importantly, try the mattress if you can.