Mattress Firmness Guide: What Level Is Best and Why

Key Takeaways

I've learned that finding the right mattress firmness level comes down to these key points:

• Start with Body Weight: This is the most important factor in choosing a firmness level.

• Firmness is Subjective: There is no industry standard. What feels firm to a 65kg person will feel soft to a 110kg person.

• Sleeping Position Refines the Choice: Your preferred position helps narrow it down. Side sleepers generally need a softer mattress for pressure relief, back sleepers a medium-firm mattress, and stomach sleepers a firmer mattress for support.

• Springs = Support, Foam = Feel: The springs dictate your spinal alignment and support, while the foam layers on top create the comfort "feel".

• Adjustability is Key: You can't perfectly predict comfort. The best mattress system provides a good starting point and allows you to fine-tune the firmness level at home.

Firmness Depends on You, Not the Label

The mattress industry has made this simple concept unnecessarily confusing. The core concept is simple: the ultimate question of mattress firmness comes down to how hard or soft the mattress feels.

But the label alone is never enough. You'll see marketing hype about "cloud-like softness" and "orthopaedic support," but nobody tells you the truth: the wrong firmness level will ruin even the highest-quality mattress, while the right firmness can make a budget mattress feel perfect. I believe this is the single most overlooked factor in the entire industry. The term “firmness” is completely subjective.

What a 60kg person feels is "Firm" might feel like a "Medium" to someone much heavier. Heavier folks, or heavier sleepers, often require firmer mattresses to prevent excessive sinkage and maintain proper support.

Understanding the Mattress Firmness Scale: How We Measure Support

At Ausbeds, we use a firmness scale from 2 to 16, where:

• 2-4 = Softer (this is the softest mattress range, with deep contouring) 

• 5-7 = Medium (balanced support and comfort, what some call medium soft or medium firm) 

• 8-10 = Firmer (more supportive, less sinkage) 

• 11-16 = Very Firm (maximum support, minimal contouring) 

There is no industry standard for firmness. A "medium" at one company feels completely different from a "medium" at another. This is why buying a mattress online based on a generic firmness description is like buying jeans without knowing the actual measurements—you're guessing. A mattress purchase shouldn't be a guess.

Our 2-16 firmness scale is based on specific component combinations: the spring tension (soft, medium, or firm), the latex density (soft, medium, or firm), the position of the spring unit (soft side up or firm side up), and the placement of the felt layer (above or below the springs). Every configuration produces a measurable, repeatable firmness level.

The Body Weight to Firmness Formula: Your Starting Point

This is the single most important piece of data I can give you, and it's based on 15 years of real customer data from thousands of mattresses. This is the best mattress selector to start with.

Why does body weight matter so much? 

Think about physics. A 50kg person lying on the same mattress as a 120kg person will sink to completely different depths. Gravity and body weight are the main factors determining how a mattress supports you. Your body type dictates how much support you need.

As I tell customers in the showroom: "A 50kg person will find the majority of mattresses 'too firm,' while a 120kg person will find the majority of mattresses 'too soft.' That same mattress will feel completely different to each person." 

How Do I Know If My Mattress Is Too Firm or Too Soft For Me?

I use the car analogy because I haven’t found a better way of explaining it: Think of the springs as the suspension for your body.

Imagine you have a big, heavy pickup truck. The suspension is shot, so you take it to the mechanic. But they mistakenly install suspension designed for a small, lightweight sedan. You drive away. At first, maybe it feels okay. But soon, you notice problems. The truck leans heavily around corners. It bottoms out going over bumps. You complain, “This suspension is crap!” 

You take it back. A knowledgeable mechanic looks at it and says, “Mate, there’s nothing wrong with the quality of this suspension. It’s just the wrong suspension for the weight of your truck. You need heavy-duty springs.” 

Conversely, if you put a truck suspension in that little sedan, the ride would be harsh and bumpy. You’d feel every crack in the road because the springs are too stiff to absorb the impact properly for the car’s lighter weight.

Mattresses are human suspension systems. Their job is to suspend your body correctly in the air while you sleep, keeping your spine aligned. This is the core of firmness and support.

What Happens When Spring Tension Doesn't Match Body Weight

If you're too light for the springs: Your body won't compress the springs enough. Instead of the springs yielding to your body, your body yields to the springs. This causes your spine to contort and stretch during the night, leading to pressure points and morning stiffness. This is why the softest mattress options exist.

If you're too heavy for the springs: You'll experience a "hammocking effect"—your body falls through the comfort layers and sinks too deeply. You lose core support and end up in a hole. Your spine falls out of its natural alignment range.

About 60% of mattress problems I see in my factory come from spring tension to body weight mismatches. This is the foundation—if you get this wrong, no amount of expensive foam on top will fix it.

The 80/20 Rule: Why Firmness Preference and Body Type Are So Personal

80% of customers fit perfectly into the body weight recommendations above. They order their recommended firmness level, maybe adjust it by ±1 level at home, and they're sleeping perfectly within a week.

But 20% of customers are outliers, and firmness preference for them is highly individual and can't be predicted from body weight alone. Your unique body type plays a huge role.

Real Examples from My Customer Base:

• Gold Coast Customer: 95kg → Standard recommendation was Cloud 9 → Ended up on Cloud 3 (much softer) 

• Melbourne Customer: 95kg → Standard recommendation was Cloud 9 → Ended up on Cloud 12 (firmer) 

Same weight. Opposite preferences. 

Why This Happens: The Hidden Factors

As I've told customers for years: "For comfort, it's all about bodyweight/personal preference. And everyone is different here. Everyone has a different expectation when it comes to feel." "I have 15 mattress feels in my business for this reason. People buy super soft, all the way to super firm and everything in between." 

Firmness preference is shaped by many factors beyond body weight: 

• Previous mattress history: If all your mattresses were very firm before, a medium Ausbeds mattress might feel soft to you. If you're coming from a very soft pillowtop, our medium might feel firm. It's a game of comparison.

• Sleeping position habits: Strict side sleepers need more contouring for shoulders and hips. Back sleepers need balanced support. Stomach sleepers need firmer support to prevent the lower back from arching.

• Personal comfort associations: What feels "normal" to you based on years of sleeping habits. Some people prefer to sleep "on" a mattress, others prefer to sleep "in" a mattress.

• Temperature sensitivity: Some prefer less foam contact to sleep cooler.

• Body shape and muscle distribution: Muscle weighs more than fat, shoulder width, hip width—all affect pressure distribution. This is all part of your unique body type.

This is why we built the Ausbeds system to be fully adjustable. We don't pretend to predict your perfect mattress from a quiz. We give you a scientifically-backed starting point, then let you fine-tune it during your trial period.

Your Sleeping Position and Firmness: The Guidelines

Your sleeping position is the next most important factor after body weight.

Side Sleepers

Recommended Range: Levels 3-7 (softer to medium) 

Side sleeping creates the most pressure on the shoulders and hips. You need the mattress to contour deeply enough that these pressure points don't bottom out on the springs. A plush mattress or one from the softest mattress range is often the right mattress for side sleepers to achieve pressure relief.

What I see in the showroom: Side sleepers often choose mattresses that are too firm because they confuse "support" with "firmness." They wake up with shoulder pain and don't understand why. The answer: their shoulder didn't sink enough into the mattress, so all their body weight concentrated on that one point all night. They didn't get the cushioning they needed.

Back Sleepers: The Case for a Medium-Firm Mattress

Recommended Range: Levels 6-9 (medium to firmer) 

Back sleepers need balanced support—enough cushioning for the lumbar curve, but not so soft that the hips sink too deeply. This is why a medium-firm mattress is often the gold standard for back sleepers, as it promotes good spinal alignment.

Common mistake: Going too soft. When the hips sink too far, the spine arches unnaturally, leading to lower back pain.

Stomach Sleepers

Recommended Range: Levels 9-12 (firmer to very firm) 

When you sleep on your stomach, there are no shoulders or hips that need to be absorbed into the mattress. Also, when you are on your front, if your stomach drops into the mattress, it can overarch your back, causing some pain in the small of your back.

Stomach sleepers in my shop get firmer springs. Otherwise, the back arches in. A firm bed is essential for stomach sleepers to maintain a neutral spine. However, if you only occasionally sleep on your stomach, it shouldn't be a big deal.

Debunking Myths About a Firm or Soft Mattress

I hear these all the time. Let's clear up the two biggest myths about mattress firmness.

Myth #1: "A firm mattress is good for your back"

The truth: This isn't accurate. Here's what I tell customers:

A 50kg person will find a large majority of mattresses 'too firm,' while a 120kg person will find the majority of mattresses 'too soft.' These two weight ranges will sink to very different depths into the mattress. That same mattress will feel completely different to each person.

A truer statement might be: if you have a bad back, you have much more to gain by getting the fit exactly right. Some back problems like slipped discs can require an extremely firm mattress to prevent the vertebrae from squashing the swollen discs. But usually, if someone has a bad back and asks me what's the best mattress, I tell them the same as I tell everyone: The one that fits.  The goal is proper spinal alignment, not just a hard surface.

Myth #2: "Soft mattresses cause sagging"

The truth: Springs don't sag—foam sags. And foam sags faster when it's compressed too much.

And here's the kicker: when springs are too firm for your body weight, the foam gets compressed MORE, which speeds up degradation. Manufacturers put very firm springs in mattresses thinking they're making them durable, but they're actually causing the problem.

Get the right spring tension where the body is in the correct position, and there's no need for excessive amounts of foam.

Firmness and Support: Why Spring Tension Matters More Than Foam

I have mattresses set up in my showroom that are exactly the same, except for one thing: the wire in the pocket-spring is 0.1mm different.  They feel completely different. One is medium. The other feels very firm. 

The gauge of the wire is the biggest predictor of how the mattress will distribute your body weight pressure. This is the real source of support in modern innerspring mattresses (or pocket spring mattresses).

To me, polyfoam is just soft stuff I put on my lowest cost mattress so they can't feel the springs. Changing the polyfoam on my springs has far less effect on the overall comfort and support than changing the thickness of the steel in my pocket springs by 0.1mm. This is how I adjust for different weights and personal preferences. I adjust the metal by 0.1mm. It has a huge effect.

The foam changes the feel. The springs decide the body shape.  This is the most important concept in firmness and support.

Think of it like a house foundation: if you have cracked walls, you don't blame the concrete—you blame the foundation. You can formulate the best concrete in the world, but if the earth beneath it shifts, it's not going to work.

Material Firmness: Latex vs Memory Foam vs Polyfoam

Over 12+ years, I've tested all three comfort materials. These comfort layers sit on top of the springs and are responsible for the mattress's feel and pressure relief.

Polyfoam (Plastic with bubbles in it)

• Cheapest option 

• Dips faster than latex 

• Used in our Cooper model for budget-conscious buyers

Memory Foam

• Great for reducing partner disturbance 

• Heat sensitive—softer in summer, firmer in winter 

• Doesn't biodegrade 

• A memory foam mattress has a distinct "sinking" feel that some love and others dislike.

Latex (Tree sap with bubbles in it)

• Most expensive 

• In blind tests in my shop, most people prefer its feel 

• Bouncier than the other two—the bounciness is the latex pushing up into the crevices of your body 

• When you lay on latex, the foam sets and doesn't move. It doesn't compress over the course of the night's sleep

Latex on pocket springs is, to me, the best combination of materials for a mattress.  It provides the best blend of support and cushioning.

How to Test Firmness: What to Look For

When you're lying on a mattress in a showroom (or at home during your trial), here's what you should focus on.

Priority #1: It MUST "feel good when you are laying on it"

 Lie down, close your eyes. A neutral feel is what you're aiming for. We're trying to divert pressure away from your pressure points in order not to contort your spine. This is how you relieve pressure.

Ask yourself: 

• Is it pressing against your butt? Too firm 

• Do you feel like you're sinking? Too soft 

• Does your spine feel aligned in its natural curve? Just right. This is neutral spinal alignment.

Which mattress that will do this for you will be different for everyone. I have 15 mattress feels in my business for this reason. People buy super soft, all the way to super firm and everything in between."

Priority #2: It MUST "feel good when you are laying on it, for a really long time"

This is why we use latex and high-quality springs. A mattress might feel perfect in the showroom, but if it dips in 2 years, you've wasted your money.

Common Firmness Mistakes and How to Avoid Them

Mistake #1: Choosing firmness based on what someone else recommends

When you ask someone on a forum which mattress you should get, you are asking which mattress feels good when they are lying on it. This is like asking a stranger on the internet what size jeans you should get. They don't know, they can't know. This is not a good way to find the right mattress firmness.

Mistake #2: Not giving the mattress time to break in

Some mattresses (especially latex) can feel firmer in the first 1-2 weeks. Your body also needs time to adapt if you're coming from a very different mattress type. Give your new mattress 1-2 weeks before making adjustments. 

Mistake #3: Confusing "firmness" with "support"

A mattress can be soft but still supportive. It's about keeping your spine aligned, not about how hard the surface feels. A plush mattress can offer excellent support if the springs are right for your body weight.

Mistake #4: Ignoring your base/foundation 

The frame of a mattress is like a foundation for a house. You wouldn't want to build a house on an unsteady foundation, just like you wouldn't want to put a mattress on an unsteady frame. Flexible slats are the absolute devil. They cause mattresses to sag prematurely because the mattress takes the shape of the slats beneath. Avoid curved upward-style slats. Make sure they are solid and the gap isn't too big. 

The Trial Period: How to Use It Effectively to Get The Mattress Firmness Right

For 80% of customers:

• Use the body weight chart 

• Order your recommended firmness level (3, 6, 9, or 12) 

• Test for 1-2 weeks—give your body time to adapt to the new mattress 

• Adjust ±1 level at home if needed 

• Enjoy your mattress 

For 20% with special situations (outliers). You might be in the 20% if: 

• The standard recommendation feels obviously wrong after 1-2 weeks 

• You've had mattresses before and know you prefer much softer or firmer than "typical" 

• You've made DIY adjustments but still haven't found the right feel 

• You're coming from a very different mattress type (floor bed, waterbed, ultra-soft pillowtop) 

What to do: 

• Start with your standard recommendation 

• Test for 1-2 weeks 

• Make DIY adjustments (flip springs, move felt) 

• Contact us if still not right—we'll swap components until it's perfect 

• Use your 2 free component swaps (first 3 months) 

• Trial period extends to 9 months if needed 

• Contact: (02) 8999 3333 | sales@ausbeds.com.au 

We'll find your perfect firmness through testing and adjustment, not prediction.

Final Thoughts: Why Adjustability Is the Key to the Perfect Mattress

The Ausbeds system is built for outliers. We don't pretend one firmness fits all. We are Australian made and our system gives you:

• Hundreds of possible firmness combinations 

• Springs that can be swapped to different tensions 

• Latex layers that can be changed 

• A thin layer of felt for quick adjustments 

• Everything is modular and accessible 

Most important: These are starting points, not permanent decisions. The mattress is designed to be adjusted and refined during your trial period.

After 15 years of doing this, I've learned that the perfect mattress isn't the one you buy—it's the one you fine-tune. And that's exactly what we've built at Ausbeds.

Ready to find your perfect firmness level?

Visit our Marrickville showroom to try the firmness levels yourself, or call us at (02) 8999 3333 to discuss your specific needs.