How to choose the right mattress firmness
A person weighing 55 kg and one weighing 105 kg can sleep on the same mattress, but they will hardly need the same support. That's why understanding how to determine mattress firmness is crucial: it doesn't mean choosing the stiffest model, but rather finding one that keeps the spine in a natural position without creating annoying pressure on the shoulders, hips, and legs.
Firmness is one of the parameters that most affects the quality of rest, especially if you wake up with lower back pain, tingling in the limbs, or the feeling of having "sunk in." To evaluate it properly, you need to consider weight, body distribution, sleeping position, mattress structure, and the bed base it will rest on.
What is mattress firmness?
Firmness indicates the mattress's ability to support the body when loaded. In practical terms, it describes how much the sleeping surface can resist weight and maintain its ergonomic qualities over time. It doesn't simply equate to perceived rigidity.
A mattress can feel welcoming on the surface yet still have high firmness thanks to a supportive internal core or a well-calibrated spring system. Conversely, an initially firm surface doesn't automatically guarantee proper support: if it doesn't adapt to the body's shape, it can leave the shoulders and hips too elevated, forcing the spine into an unnatural posture.
It's also useful to distinguish firmness from maximum weight capacity. Weight capacity indicates the load a structure can bear without damage, while firmness concerns the mattress's functional response to a person's weight. To choose well, it's not enough to know that the product can support a certain number of kilograms: you need to understand if that support is adequate for your body and posture.
How to determine mattress firmness based on weight
Body weight is the first data point to evaluate, but it should not be considered in isolation. Two people of the same weight can exert different pressure on the mattress: a tall build distributes the load over a larger surface, while a more compact build concentrates more weight on the shoulders and hips.
Generally, people weighing up to about 60-65 kg tend to benefit from medium or medium-soft firmness, as long as the mattress maintains good central support. A model that is too firm might not allow the shoulder to sink in enough, especially when sleeping on the side, and could generate cervical tension.
Between 65 and 90 kg, the most frequent choice is medium or medium-firm support. This is a broad range, where sleeping position and personal preferences make a concrete difference. Those who sleep on their back may appreciate more stable support in the lumbar area; those who primarily sleep on their side may seek more conformity in the shoulder and hip areas.
Above 90-100 kg, a structure with medium-high or high firmness is generally needed, capable of supporting the pelvis without sagging and maintaining correct ergonomics over the years. This doesn't mean having to choose a hard surface: a mattress for robust body types can have comfortable top layers, provided the supporting core is adequate. In these cases, thickness, material density, and the quality of the bed base become particularly important factors.
Couple's weight should not simply be added together
For a double bed, the evaluation is not limited to the couple's total weight. Each person's weight, the difference between the two partners, and how much movement occurs during the night matter. If one person is much heavier than the other, a mattress that is too uniform may be too firm for one and too soft for the other.
Pocket springs with differentiated zones are often a valid solution when it's necessary to limit motion transfer and support significant weights. Some high-density Memory foam mattresses can also offer a balanced response. The best solution depends on the internal construction, not just the material's name alone.
Firmness, posture, and sleeping position
The correct firmness must work in conjunction with posture. The goal is simple: when lying down, the spine should maintain as natural an alignment as possible, without curving upwards or downwards.
Those who sleep on their side need a mattress that accommodates the shoulder and hip while keeping the waist area supported. If the firmness is excessive, the shoulder remains compressed, and the neck can lose alignment. If it's too low, however, the pelvis sinks excessively.
Those who sleep on their back require good balance in the lumbar region. An excessively soft mattress allows the pelvis to sink, increasing tension in the lower back. A model that is too firm, on the other hand, may not follow the natural curves of the body and can create a feeling of constant pressure.
Those who sleep on their stomach should pay even more attention to the stability of the support. In this position, excessive softness tends to cause the pelvis to drop, accentuating the lumbar curve. Medium-firm support is often more appropriate, but it should be balanced with a low pillow and a surface that isn't unpleasantly hard.
Materials influence firmness, but do not define it alone
Saying that a Memory foam mattress is soft or a spring mattress is firm is an oversimplification that can lead to a wrong choice. Each technology can offer different levels of support based on its composition, thickness, and ergonomic design.
Memory Foam distributes pressure and gradually molds to the body. To be suitable for heavier individuals, it must have internal density and structure designed to prevent excessive sinking. Versions with Memory Gel can improve heat dispersion, a useful aspect for those who tend to sweat at night, but thermoregulation does not replace the evaluation of firmness.
Latex offers immediate elasticity and a more responsive feel to movements. It can be a good choice for those seeking comfort without the enveloping sensation of Memory foam, but it must have a thickness and density consistent with the user's weight.
Pocket springs work precisely: each spring responds to the load of the area it acts upon. They are particularly appreciated by those who desire greater support, by many couples, and by people with a robust build. The number of springs, however, is not a sufficient indicator: the gauge, firmness zones, and comfort layers above the springs also matter.
Don't overlook the bed base, thickness, and signs from your old mattress
A correctly chosen mattress can perform poorly on an inadequate bed base. Slats that are too far apart, curved, broken, or lacking central support in a double bed alter the response of the sleeping surface. An excessively yielding base can also make a mattress designed to offer medium or firm support feel softer.
Thickness deserves the same attention. For an adult, especially with medium-to-high weight, a structure that is too thin has less margin to combine surface comfort and deep support. This doesn't mean that every tall mattress is better, but adequate height often allows for building layers with distinct functions: comfort, ergonomics, and firmness.
There are also daily signs that help recognize when firmness is no longer suitable. If you wake up with lower back pain that improves during the day, if you sleep better away from home, if you perceive a stable sag in the hip area, or if turning in bed requires effort, the mattress may have lost its ability to properly support the body.
A useful test: observing true alignment
Whenever possible, the most concrete evaluation is done by lying in your usual position for a few minutes. It's not enough to sit on the edge or press the mattress with your hand: the body distributes weight very differently.
On your side, have someone observe the line from your neck to your lower back. If the spine appears curved towards the mattress, the support may be too soft; if it remains arched upwards because the shoulder doesn't find space, it may be too firm. On your back, the correct sensation is of diffused support, without a marked lumbar void or excessive pressure on heels, shoulders, and sacrum.
The initial impression of comfort matters, but it is not the only criterion. A very soft mattress may seem pleasant for a few minutes and prove insufficient after a whole night. Likewise, a more structured support sometimes requires a short period of adaptation, as long as it does not cause persistent pain or pressure points.
This is why a guided choice, based on weight, posture, thermoregulation needs, and back conditions, is more reliable than the label "firm" or "soft." JoyShop Mattresses directs this evaluation towards the sleep system most consistent with personal needs.
The right mattress shouldn't make itself known in the morning: it should allow for a more fluid awakening, a supported back, and the feeling of having truly rested.
