If you're under 70kg, a standard firm mattress is usually enough. Between 70 and 90kg, firm to super firm tends to work better. Above 90kg, most people need super firm or extra firm to avoid the core compressing under load. Weight matters more than most buying guides admit.
Who This Guide Is For
This guide is for anyone comparing firm, super firm and extra firm mattresses and unsure which one actually matches their body weight. It's particularly useful if you've bought a "firm" mattress before and found it went soft or started sagging faster than expected.
Why Body Weight Changes the Firmness You Need
Mattress firmness ratings are not absolute. A mattress rated firm is tested and marketed based on an average body weight. A lighter person lying on that same mattress feels a firmer, more resistant surface, because their weight doesn't compress the support layer very far. A heavier person on the same mattress compresses it further, so the identical mattress can feel noticeably softer.
This is why two people can buy the same "firm mattress" and have completely different experiences. It's not inconsistency in the product, it's physics. The heavier the sleeper, the more force is pushing down into the support layer, and the more that layer needs to resist before it starts to feel like it's giving way.
Firmness Comparison Table
| Firmness | What it feels like | Best suited to |
|---|---|---|
| Firm | Solid support with some give from the comfort layer on top | Back and stomach sleepers transitioning from softer beds, lighter sleepers |
| Super Firm | Minimal comfort layer, support structure close to the surface | Back and stomach sleepers, heavier sleepers, people with lower back pain |
| Extra Firm | Almost no give, denser core, closest to a flat solid surface | People who find super firm still too soft, those on medical advice to avoid sinking |
Key Decision Factors
- Body weight bandsUnder 70kg, a firm mattress typically provides enough resistance. 70–90kg, super firm tends to hold its support better over years of use. 90kg and above, a genuinely dense core (coconut coir or dense latex) resists compression better than a foam comfort layer.
- Construction matters as much as the labelA coconut pad core resists compression differently to a foam-topped spring mattress, even under the same "firm" label. Coconut coir holds its shape under sustained weight rather than compressing and losing density over time.
- Couples with different body weightsPocket spring builds respond independently to each side of the bed, which can help balance compression rather than one side sagging faster.
- Warranty noteStructural warranty length varies by model, generally between 2 and 20 years, and does not cover the fabric cover. Check the specific product page for the exact term.
- Returns noteMattresses are not eligible for change-of-mind returns or Buyer's Protection. A genuine structural fault is handled through the warranty process.
Use-Case Decision Framework
Product Recommendation
Super Firm Coconut Pad Mattress BD20
Coconut coir core built to hold its shape under sustained higher body weight rather than compressing over time. Best suited to sleepers in the 90kg+ range.
Why we recommend this: the dense coir structure resists the gradual sagging that foam-topped mattresses develop under consistent heavier load.
Double-Sided Coconut Padding Super Firm Spring Mattress BD1716
Combines a pocket spring base with coconut coir, so each side of the bed responds independently. Best for couples with a notable weight difference.
Why we recommend this: independent coil response means one sleeper's weight doesn't drag down the support on their partner's side.
Browse the full range in our firm mattress collection, or visit our Clayton warehouse to test how different constructions actually feel under your own body weight.
