Christmas & New Year Break: Our shop is closed 25 December – 7 January. You can still place orders online, and they’ll be processed when we return on 8 January.
Christmas & New Year Break: Our shop is closed 25 December – 7 January. You can still place orders online, and they’ll be processed when we return on 8 January.
📢 Update: You can now contact us by landline 02 6685 6722 or Shop Mobile 0490 078 621 — available for both calls and texts.
You can have the most beautifully made, genuinely certified organic latex mattress in the world — and still sleep poorly on it if you choose the wrong firmness. Firmness is not a minor detail or a matter of personal taste alone. It is the single most consequential variable in how a mattress performs for your body night after night. Get it right and you wake refreshed, free of aches, and well-rested. Get it wrong and you spend months — sometimes years — wondering why your expensive mattress is not delivering the sleep you expected.
Yet firmness is also one of the most misunderstood concepts in the mattress industry. Retailer descriptions are inconsistent — one brand’s “medium” is another brand’s “firm.” Marketing language conflates firmness with quality, implying that firmer mattresses are more “supportive” and therefore better. And most buyers make their firmness decision in a showroom after lying on a mattress for sixty seconds while fully clothed — a completely inadequate basis for a choice that will affect their sleep for the next fifteen to twenty years.
This guide changes that. We will explain what firmness actually is, what it is not, how different body types and sleeping positions interact with firmness, the specific health conditions that should inform your decision, and exactly how to navigate the choice between soft, medium, and firm in the context of Zentai Living’s certified organic latex mattress range. We will also cover dual firmness — one of the most practical solutions available for couples — and explain what to do if you get it wrong.
By the end of this guide, you will have the clarity to choose with confidence.
Mattress firmness refers to the initial feel of resistance when you first lie down on a sleeping surface. It describes how much the mattress yields — or pushes back — under the weight and pressure of your body at the point of contact. A soft mattress yields readily, allowing your body to sink into it. A firm mattress resists, keeping your body closer to the surface.
Firmness is measured on most industry scales from 1 to 10, with 1 being the softest imaginable surface and 10 being completely unyielding. In practical retail terms, the most commonly used categories are:
At Zentai Living, our certified organic latex mattresses are available in Soft, Medium, and Firm profiles, with a Dual Firmness option that combines Medium and Firm on opposite halves of the same mattress.
This distinction is critical and widely misunderstood — including by many people who sell mattresses for a living.
Support refers to the mattress’s ability to maintain correct spinal alignment throughout the night — keeping the spine in a neutral position regardless of sleeping posture. A supportive mattress distributes body weight evenly, prevents the hips from sinking excessively, and ensures the lumbar curve is neither flattened nor exaggerated.
Firmness refers to surface feel — how the mattress feels when you first make contact with it.
These two properties are related but not synonymous. A soft mattress can be highly supportive if its underlying structure maintains spinal alignment even as the surface yields to body contours. A firm mattress can be poorly supportive if it creates pressure points that push the body out of alignment. The goal is to find a firmness level that provides both appropriate surface comfort AND underlying structural support for your specific body.
In the context of organic latex mattresses, the Dunlop latex used in Zentai Living’s mattress cores provides excellent structural support across all firmness levels. The firmness option you choose determines how much the surface yields to your body — the support structure beneath it is consistent and reliable regardless of which firmness you select.
One of the most important variables in firmness perception is body weight. Firmness is not an absolute quality — it is an interaction between the mattress material and the force your body exerts upon it. A mattress that feels perfectly medium to a 60kg person may feel noticeably firm to an 85kg person lying on the same surface, because the heavier person exerts greater downward force and therefore compresses the mattress more deeply.
This is why firmness recommendations cannot be made by feel alone in a showroom — and why any mattress guide that gives blanket firmness advice without accounting for body weight is giving you incomplete information.
Choosing the right firmness requires understanding how four key variables interact: your sleeping position, your body weight, your health considerations, and your personal comfort preference. We will work through each in detail.
Your primary sleeping position is the single most important determinant of optimal firmness. Different positions place your body’s weight on the mattress in fundamentally different ways, creating different pressure points and different spinal alignment requirements.
Side sleeping is the most common sleeping position among Australian adults, and it creates the most demanding pressure point requirements of any position. When you lie on your side, your body’s weight is concentrated at two primary points: the shoulder and the hip. These bony prominences protrude further than the rest of your body, meaning that if the mattress does not yield sufficiently at these points, they bear disproportionate pressure — leading to discomfort, numbness, and restricted circulation during the night.
For spinal alignment in the side position, the mattress must yield enough at the shoulder and hip to allow the spine to remain in a straight horizontal line from the base of the skull to the tailbone. If the mattress is too firm, the shoulder and hip are pushed upward, creating a lateral curve in the spine — the equivalent of sleeping in a slight C-shape. If the mattress is too soft, the hip sinks excessively while the shoulder stays relatively elevated, creating the opposite curve.
Recommended firmness for side sleepers:
Back sleeping is widely considered the most physiologically neutral sleeping position. When lying on your back, body weight is distributed across a larger surface area — the back of the head, shoulders, upper back, sacrum, and heels — reducing peak pressure at any single point. The primary alignment concern in the back position is the lumbar curve: the mattress must support the natural inward curve of the lower back without either allowing the hips to sink excessively (which flattens the lumbar curve) or pushing the lumbar region upward (which exaggerates it).
Recommended firmness for back sleepers:
Stomach sleeping is the least recommended sleeping position from a spinal health perspective. When lying face down, the cervical spine is rotated to one side for the entire duration of the sleep — creating significant strain on the neck, the cervical vertebrae, and the soft tissue of the upper back and shoulders. Physiotherapists and sleep specialists consistently advise against stomach sleeping for those with neck or back concerns.
If you are a committed stomach sleeper and unable or unwilling to change position, the primary mattress requirement is firmness — specifically, enough resistance to prevent the hips and abdomen from sinking into the mattress and creating a hyperextended (arched) position in the lumbar spine. A mattress that is too soft will allow the stomach and hips to sink deeply, exaggerating the lumbar curve and placing significant compressive load on the lower back over hours of sleep.
Recommended firmness for stomach sleepers:
Many people — perhaps the majority — do not sleep exclusively in one position. Combination sleepers shift between two or three positions during the night, often moving through side, back, and occasionally stomach positions in the course of a single sleep. This is entirely normal and reflects the body’s natural tendency to redistribute pressure during sleep.
For combination sleepers, the optimal firmness sits in the middle of the range — firm enough to support the back position, soft enough to cushion the side position. Medium is almost always the right starting point for combination sleepers of average body weight, with adjustments toward softer or firmer based on which position dominates and the individual’s weight.
Recommended firmness for combination sleepers:
As discussed above, body weight fundamentally changes the way firmness is experienced. The following framework provides a practical guide for adjusting firmness recommendations based on weight:
Under 55kg: The lightest sleepers often find that standard “medium” firmness feels relatively firm because their body weight does not compress the latex sufficiently to reach the mattress’s full conforming potential. Lighter sleepers typically benefit from going one level softer than their sleeping position alone would suggest. In our range, soft or medium-soft is often appropriate for lighter side and back sleepers.
55–75kg: This weight range is the closest to the “average” for which most firmness descriptions are calibrated. Recommendations based on sleeping position alone are most reliable in this range. Medium is the most common optimal choice for combination and back sleepers; medium-soft to medium for side sleepers.
75–95kg: At this weight range, the interaction between body weight and mattress firmness begins to shift meaningfully. Sleepers in this range often find that what presents as “medium” in a showroom feels softer in practice over a full night of sleep, particularly if they sleep warm (heat softens latex slightly). Moving one level firmer than position alone suggests is often appropriate.
95kg and above: Heavier sleepers place substantially greater demands on a mattress. For support, comfort, and long-term durability, firmer latex is consistently the better choice. Our Firm profile is appropriate for most heavier sleepers across all positions except pure side sleeping, where medium-firm may be preferable to avoid excessive shoulder and hip pressure.
Certain health conditions have direct and specific implications for mattress firmness selection. If any of the following apply to you, factor them into your decision alongside the position and weight considerations above.
Lower back pain is the most common musculoskeletal complaint among Australian adults and one of the most frequent drivers of mattress replacement decisions. The relationship between mattress firmness and back pain is more nuanced than the conventional wisdom (“firm mattresses are better for your back”) suggests.
Research consistently indicates that medium firmness is the most broadly beneficial choice for non-specific lower back pain. A landmark study published in The Lancet found that medium-firm mattresses produced significantly better outcomes for lower back pain sufferers than firm mattresses — challenging decades of conventional wisdom about “orthopaedic” firmness. The reason is intuitive: a mattress that is too firm creates pressure points at the hips and shoulders that push the spine out of alignment, while a mattress that is too soft allows the hips to sink, creating the same misalignment from the opposite direction. Medium firmness threads the needle between these two failure modes.
For lower back pain specifically in side sleepers, softer to medium firmness is typically appropriate to ensure adequate hip and shoulder cushioning. For back sleepers with lower back pain, medium to medium-firm often provides the lumbar support needed without the pressure point issues of firm mattresses. If your back pain is concentrated in the sacroiliac region or is associated with disc issues, we strongly recommend discussing your situation with us directly — our experience with back pain customers is extensive and nuanced.
Shoulder pain — whether from rotator cuff issues, bursitis, or arthritis — is acutely aggravated by sleeping on a surface that is too firm. The shoulder, when loaded in the side sleeping position, requires meaningful cushioning. A firm or even medium-firm mattress can create sufficient pressure at the shoulder to exacerbate inflammation and cause significant pain that disturbs sleep and increases soreness during the day.
For shoulder pain sufferers who primarily sleep on their side, soft to medium-soft firmness is usually the most appropriate choice in organic latex. The same principle applies to hip pain — whether from hip bursitis, hip arthritis, or other hip joint conditions — where the need for pressure relief in the side position is paramount.
Scoliosis and other structural spinal conditions create asymmetrical pressure distribution on any sleeping surface. The appropriate firmness for a scoliosis patient depends on the nature, severity, and location of the curvature, as well as the individual’s preferred sleeping position. There is no universal recommendation for this group. We strongly encourage anyone with diagnosed scoliosis or significant spinal conditions to consult both their treating physiotherapist or orthopaedic specialist and our team before selecting a firmness.
Fibromyalgia and similar conditions characterised by widespread musculoskeletal pain and heightened sensitivity to pressure create a strong need for a genuinely cushioning sleeping surface. Pressure sensitivity means that even moderate firmness levels can feel uncomfortably rigid and contribute to pain amplification during sleep. Soft to medium-soft organic latex — chosen for its pressure-relieving properties without the heat retention of memory foam — is frequently the most appropriate choice for fibromyalgia sufferers.
Pregnancy changes both sleeping position requirements and pressure sensitivity significantly. As pregnancy progresses, side sleeping becomes both medically recommended (for optimal blood flow) and practically unavoidable. The growing abdomen places increased lateral pressure on the hips and the lumbar region in the side position, typically increasing the need for pressure relief at the hip.
For most pregnant women, medium to medium-soft firmness is appropriate — soft enough to cushion the hip and accommodate the changing body shape, firm enough to maintain lumbar support. A full-length body pillow used in conjunction with the mattress can address specific pressure point concerns without requiring a softer mattress overall.
After accounting for sleeping position, body weight, and health considerations, the remaining variable is personal preference — the subjective experience of what feels right and comfortable to you. This is real and valid, and should not be dismissed even when it runs counter to the recommendations above.
Some people genuinely prefer sleeping on a firm surface and find softer mattresses claustrophobic or uncomfortable regardless of what the position-and-weight matrix suggests. Others have always slept on soft mattresses and find the transition to a firmer surface disorienting, even if a firmer mattress would theoretically provide better alignment.
Within the limits set by spinal health — avoiding choices that clearly compromise alignment — personal comfort preference is a legitimate factor. Our strong recommendation is to visit our Byron Bay showroom and spend genuine time lying on each firmness option in your typical sleeping position before making a decision. Ten to fifteen minutes per option is a meaningful trial. Bring your partner if you share a bed. Wear comfortable clothing that allows you to relax fully. This experience is genuinely useful and will give you information about your preferences that no amount of reading can provide.
One of the most practical challenges in mattress selection arises when two people who share a bed have meaningfully different firmness needs. A lightweight side-sleeping woman and a heavier back-sleeping man may have optimal firmness requirements that are two or even three levels apart. The conventional solution — choosing a compromise firmness that satisfies neither partner fully — is unnecessary with Zentai Living’s dual firmness option.
Our dual firmness mattresses are manufactured with two distinct latex cores side by side within a single mattress — one half at Medium firmness, the other at Firm. Each partner sleeps on the firmness that suits their individual needs, with no compromise required. The join between the two firmness zones is engineered to be invisible and unfelt in normal sleeping positions, and the mattress presents as a single unified product in terms of cover, appearance, and construction.
Dual firmness is available across most of our mattress range and is one of the most popular configurations among couples purchasing with us. It is worth noting that the dual firmness option works most effectively when the two partners have a clear preference difference — if both partners are comfortable on medium firmness, a single-firmness mattress is the simpler and equally effective choice.
Who is dual firmness best suited to:
Firmness in organic latex behaves differently to firmness in memory foam or innerspring mattresses, and understanding these differences will help you calibrate your expectations correctly.
Memory foam firmness changes with temperature — it softens as it warms under body heat, meaning the mattress you lie down on at the start of the night gradually becomes softer as the night progresses. In a warm room, or for a sleeper who generates significant body heat, this effect can be substantial.
Organic latex does not behave this way. Its firmness is consistent across the night, regardless of body temperature or room temperature. What you experience when you first lie down is what you will experience at 3am. This consistency is a significant advantage for sleepers who have found that their memory foam mattress feels too soft by the middle of the night, or who wake up feeling unsupported in the early hours.
New organic latex mattresses have a brief break-in period — typically two to four weeks — during which the latex cells open up and the mattress reaches its settled comfort level. A new latex mattress may feel slightly firmer than its final state in the first week or two of use. This is normal and expected. We encourage new customers to give their mattress at least three to four weeks of regular use before forming a definitive view on whether the firmness is right for them.
The break-in period for latex is subtle compared to the much more pronounced softening that occurs with memory foam, but it is worth knowing about — particularly if your first impression is that the mattress is very slightly firmer than you expected.
In Zentai Living’s range, the same “medium” firmness designation may feel subtly different across different mattress profiles because the total depth affects how the body engages with the support core. In a shallower mattress (15cm, for example), the body is closer to the support core at all times, which can make the mattress feel slightly firmer than a deeper mattress of the same designated firmness. In a deeper quilted mattress (23cm or 26cm), the comfort layers above the core create additional softness at the surface before the core’s support characteristics are engaged.
This means that if you are choosing between a 15cm and a 23cm mattress and are borderline between two firmness levels, the deeper mattress may allow you to choose the softer firmness with confidence, while the shallower mattress may warrant choosing the firmer option.
Use this framework to arrive at your firmness recommendation before visiting our showroom or contacting our team:
Step 1 — Identify your primary sleeping position. If you sleep in multiple positions, identify which one you spend the most time in during the night.
Step 2 — Note your body weight. Use the weight ranges provided earlier to understand whether you should adjust the position-based recommendation upward (heavier) or downward (lighter).
Step 3 — Consider any health conditions. Back pain, shoulder pain, hip issues, fibromyalgia, and pregnancy all have specific implications for firmness. Factor these in as overriding considerations where relevant.
Step 4 — Identify your partner’s requirements. If you share a bed, go through steps 1–3 for your partner as well. If your recommendations differ by more than one level, dual firmness is worth serious consideration.
Step 5 — Note your personal comfort history. What firmness level have you slept on most recently, and how did it feel? Did you find it too firm, too soft, or approximately right? Use this as a calibration point.
Step 6 — Visit our showroom or contact us. Armed with the output of steps 1–5, you are in a much stronger position to make use of the showroom experience — testing your likely firmness options with a clear framework rather than making a purely intuitive judgment.
Soft: Side sleepers under 65kg. Those with shoulder or hip pain. Those with fibromyalgia or widespread pain sensitivity. Personal preference for a plush, cushioning feel.
Medium: Side and combination sleepers of average weight (65–85kg). Back sleepers under 75kg. Most pregnant women. Lower back pain sufferers of average weight. The most broadly versatile option for those who are unsure.
Firm: Back and stomach sleepers across most weight ranges. Side, back, and combination sleepers over 90kg. Those who prefer a more grounded, supportive sleeping surface.
Dual Firmness (Medium/Firm): Couples with different firmness needs. Couples with a weight difference of 15kg or more. Any couple where one partner’s ideal firmness differs from the other’s.
Despite careful selection, it is possible to find that the firmness you have chosen does not feel right after a full break-in period. If, after four to six weeks of sleeping on your new Zentai mattress, you believe you have chosen the wrong firmness level, please contact us directly. We are committed to ensuring every customer is sleeping well on their Zentai mattress, and we will work with you to find the right solution — whether that is advice on adjusting your sleep setup, exploring a mattress overlay to modify the surface feel, or discussing other options.
A quality mattress overlay in organic latex or natural wool can meaningfully change the surface feel of a mattress — adding softness to a mattress that is slightly too firm — and is often a more economical solution than full mattress replacement when the underlying support core is appropriate but the surface firmness needs adjustment.
Firmness selection is one of the areas where our team’s experience is most valuable. We have helped thousands of Australians navigate this decision across three decades of operation — including many customers with complex health conditions, unusual sleeping arrangements, and requirements that do not fit neatly into standard frameworks.
If after reading this guide you still have questions or uncertainties about which firmness is right for you, please reach out. We offer no-pressure, genuinely expert guidance — by phone, by text, by email, or in person at our Byron Bay showroom.
Visit our showroom: 1/8 Banksia Drive, Byron Bay NSW 2481 Call or text: +61 2 6685 6722 | 0490 078 621 Email: [email protected] Shop online: zentai.com.au
