Choosing the wrong firmness is one of the most common reasons people end up with a mattress they don't love. This guide breaks down the firm vs soft debate for Australian sleepers — covering sleep position, body weight, and personal preference.
One of the most personal decisions in mattress shopping is choosing the right firmness level. What feels perfectly comfortable to one person can feel like sleeping on a rock — or a cloud — to another. Firmness is highly subjective, and getting it wrong is one of the most common reasons people end up with a mattress they don't love.
This guide breaks down the firm vs soft mattress debate for Australian sleepers, covering how firmness affects sleep quality, spinal alignment, and comfort based on your body weight, sleeping position, and personal preferences.
Firmness refers to how much resistance a mattress provides when you lie on it. A soft mattress allows the body to sink in more, providing a cradling, enveloping sensation. A firm mattress pushes back against the body, keeping the sleeper closer to the surface. Most mattresses are described on a scale from 1 (softest) to 10 (firmest), with medium (around 5–6) being the most popular selling range.
Important note: firmness is not the same as support. A mattress can be soft on the surface but still have excellent internal support structures. Conversely, a very firm mattress might not actually provide good spinal alignment if its support layers are poorly designed.
Stomach sleepers are the group most often recommended a firm mattress. When lying face down, a soft mattress allows the hips to sink lower than the chest and shoulders, creating a U-shaped curve in the spine. Over time, this can cause serious lower back pain and discomfort. A firmer mattress keeps the body in a flatter, more neutral position.
People over 100kg often find that a mattress rated as 'medium' by a manufacturer actually feels quite soft under their body weight. A firmer mattress provides better resistance and is less likely to develop body impressions prematurely. If you're a heavier sleeper who prefers a softer feel, look for mattresses specifically rated for higher weight categories.
Some back sleepers prefer the feeling of sleeping on a stable, flat surface rather than contouring foam. Firmer mattresses suit this preference and can provide excellent lumbar support if the firmness is appropriate.
Side sleepers put significant pressure on their hips and shoulders — the widest parts of the body. A soft or medium-soft mattress allows these pressure points to sink in slightly, relieving the pressure and keeping the spine in a neutral alignment. Sleeping on a mattress that's too firm as a side sleeper often leads to shoulder pain, hip discomfort, and disrupted sleep.
People under 65kg don't exert enough downward force to compress a medium or firm mattress to the same depth that a heavier person would. A mattress that feels medium to most people might feel quite firm to a lighter individual. Softer options provide appropriate contouring for lighter body weights.
If you have conditions like fibromyalgia, arthritis, or bursitis, a softer mattress surface can significantly reduce pain by distributing pressure more evenly across the body. This is one area where memory foam mattresses — which tend toward a softer feel — have a particular advantage.
Medium mattresses (roughly 5–6 on a firmness scale) are the best-selling category for a reason — they suit the widest range of sleepers. Most back sleepers, many side sleepers, and combination sleepers tend to do well on a medium mattress. If you're unsure what firmness to choose, medium is a safe starting point, especially if you can take advantage of a free trial period.
Many Australian mattress brands now offer adjustable firmness. Ecosa lets you rearrange internal foam layers to change the firmness. Sleeping Duck Mach II lets each side of the mattress be configured independently — ideal for couples with different preferences.
Yes, significantly. The industry commonly uses three weight brackets as a rough guide:
This is a nuanced area. For decades, conventional wisdom said that a firm mattress was best for back pain. Research has since shown this isn't always the case. A study published in the Lancet found that medium-firm mattresses were more effective at reducing chronic lower back pain than firm mattresses. The key is spinal alignment — whether soft, medium, or firm, the right mattress for back pain is one that keeps your spine in a neutral position throughout the night.
Because firmness is so personal, one of the most useful things you can do is buy from a brand that offers a proper trial period. Most reputable Australian mattress brands offer 100–120 nights, which gives your body time to adjust and gives you enough time to genuinely evaluate whether the firmness works for you. Don't judge a mattress in the first two weeks — it can take time to adapt, especially if your old mattress had a very different feel.
There's no objectively superior firmness level — it entirely depends on how you sleep, your body weight, and your personal preferences. Side sleepers and lighter people generally do better on softer or medium mattresses. Stomach sleepers and heavier people generally need more firmness. Back sleepers and couples often land on medium as a good all-rounder.
If you're unsure, choose a medium mattress from a brand with a long free trial period, and give it at least 30 nights before forming a firm opinion.
| Mattress | Price | Trial | Warranty | Rating | |
|---|---|---|---|---|---|
| Koala 🥇 Best Overall 2026 |
$1,050 | 120 nights | 10yr | 4.8/5 | View Deal → |
| Emma Best Value 2026 |
$1,149 | 100 nights | 10yr | 4.6/5 | View Deal → |
| Sleeping Duck 🥈 Best for Couples |
$1,399 | 100 nights | 10yr | 4.7/5 | View Deal → |
| Ecosa 🥉 Best Budget Pick |
$799 | 100 nights | 15yr | 4.5/5 | View Deal → |
| Ergoflex Best for Back Pain |
$1,395 | 100 nights | 7yr | 4.4/5 | View Deal → |
| Origin Best Hybrid Value |
$1,199 | 100 nights | 10yr | 4.4/5 | View Deal → |
Always look for at least 100 nights. Koala (120 nights) and Sleeping Duck (100 nights) offer some of the best trials available. A trial lets you test the mattress through different seasons including Australian summer.
A 10-year warranty is standard for quality mattresses. Ecosa offers 15 years, which is exceptional. Be wary of brands offering less than 5 years.
All-foam mattresses offer excellent motion isolation but can sleep warm. Hybrid mattresses use pocket springs under foam, improving airflow significantly — important for Australian summers.
Medium is most versatile for side and back sleepers. Stomach sleepers generally need firmer. If unsure, Ecosa lets you adjust firmness.
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