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FULL OF KNOWLEDGE BLOG ONSEN® / About Mattresses

Why does H3 mattress firmness often vary?

30 sierpnia 2025
H3 mattress, firmness level H3, mattress firmness levels
Contents
Lack of standardization in the H1, H2, H3, H4…
H3 mattress firmness in practice
Universal firmness - there is a sweet spot
Differences in perceived mattress feel
The need to standardize the scale
Osaka Air - the best choice for most people
Picking the right mattress for sleeping is a decision that affects your health, muscle recovery, and the condition of your spine. In theory, H1, H2, or H3 firmness labels are supposed to make the choice easier. A customer walks into a store, sees an H3 mattress, and assumes it’s a medium-firm product.

It turns out that H3 mattresses can vary widely. One may feel soft and flexible, while another feels too firm. Very often this leads to considerable customer confusion, because the mattress firmness scale that was meant to streamline the choice has become just a marketing tool that creates more chaos. This is because the H1–H5 scale has never been standardized. These are merely conventional labels that manufacturers use in their own way.

Lack of standardization in the H1, H2, H3, H4…

The biggest problem when assessing mattress firmness is the lack of official standards. In other technical industries we have specific units of measurement, but in the case of mattresses the industry stubbornly ignores them. Although foam manufacturers themselves use markings in newtons (N) and kilopascals (kPa), measuring force in line with ISO standards, mattress manufacturers generally resist this. The mattress firmness scale with the letter H is just marketing gibberish that every manufacturer interprets in their own way.

This means that an H3 mattress from one brand can differ radically from a mattress by another manufacturer with the same label. You’ll see differences not only between brands but even within a single company. It’s very common for two different H3 mattresses to have completely different firmness.

The problem is particularly visible in brick-and-mortar stores, where spotting the differences is only seemingly easy. More and more often, the mattress tested on display differs from the one that ultimately arrives in the bedroom. Because manufacturers don’t state firmness in objective physical units, filing a complaint later becomes problematic, since it’s harder to prove nonconformity with the offer. That’s why buying a mattress online is safer—you can return it.

H3 mattress firmness in practice

The buyer cannot rely solely on the firmness symbol of an H3 mattress, because it won’t tell them anything. For one manufacturer it may correspond to a force of 120 newtons in an ILD test, while for another it could be 100 newtons—or less or more. The issue is the lack of a standardized mattress firmness scale based on universal standards. For the customer, this means that if a seller refuses to provide the foam parameters—which is done in violation of the law—the only option left is testing the mattress in their own bedroom, so be sure to read the return terms carefully.

That’s why at ONSEN® customers get as many as 100 days to return a mattress. That’s a huge advantage over a few minutes of lying in a store, which never reflects the real sensations of a full night’s sleep. Testing at home is very simple and pleasant. You can check how the mattress responds to different sleeping positions, as well as the room temperature and your daily rhythm. This makes the choice an informed one, because it removes the risk of a poor decision.

It’s no surprise that customers increasingly compare mattresses not through the lens of H1–H5 labels, but through real reviews from other users, and sometimes tests. However, there’s a problem: most mattress rankings are not objective, but sponsored.

Universal firmness - there is a sweet spot

Despite the chaos around the mattress firmness scale, research and practice clearly show that, in reality, there is one level of mattress firmness that suits the vast majority of people. As many as about 97% of users sleep best on medium-firm mattresses, rated 6.5/10 on a ten-point scale.

Such firmness allows for a natural spinal alignment, provided the entire mattress is properly designed. The mattress should not have memory foam in the top layer so it doesn’t collapse. Placing this foam in the second layer of the mattress gives contouring without the suction/sinking effect. The remaining foams should be HR foams, which are durable and responsive. Of course, foam density and firmness, the adhesives used, and the elasticity of the cover, along with many other elements, also affect health and comfort.

The exception is a relatively small group - up to 3% of the population. This group includes younger, athletic users who sleep on their stomach. For some of these people, a slight firming of the mattress is advisable to avoid an unnatural arch in the lumbar region. However, this is a marginal share of the population; for everyone else, medium firmness is optimal.

Differences in perceived mattress feel

Mattress firmness is often incorrectly linked to the user’s weight, which doesn’t matter. In reality, body weight distributes proportionally, so mass alone doesn’t determine whether a given model will feel soft or firm—that’s what physical testing is for. Far more important are the materials used in production and, specifically, their physical properties.

A good example is memory foam. Its firmness is generally tested at a temperature of around 15°C, and it’s sensitive to heat. It’s a viscoelastic foam that hardens in the cold and becomes softer in warmth. It’s precisely this temperature response that sets it apart from other foams.

High-resilience foam, i.e. HR foam, shows no such changes. It’s a stable material that does not react to temperature, and its firmness remains largely unchanged regardless of conditions. This makes HR-foam mattresses more predictable.

In this context, it becomes clear that labels like H2 or H3 are only indicative and cause many misunderstandings. To solve the problem, we need a uniform firmness scale based on precise measurements of compressive force in newtons. Creating and implementing such a standard is a task for public authorities, because only then will consumers receive reliable and comparable information.

The need to standardize the scale

The lack of standardization makes the H firmness scale more of a marketing device than a real guideline for customers. In practice, this means a need to test mattresses yourself or to rely on the salesperson’s opinion. Let’s not forget, though, that a salesperson’s job is usually to sell and make money, not to truly help. That’s unhealthy for the market, because consumers expect transparent information but get symbols that aren’t standardized.

The solution would be to introduce a uniform firmness standard by defining exact values in newtons or kilopascals. This would let customers compare mattresses from different manufacturers reliably—just as they compare the specifications of home appliances or consumer electronics today, as well as the ingredients of food products.

Such steps could be taken by public authorities responsible for standardization and consumer protection. Standardization would not only simplify choosing a mattress, but also increase trust in manufacturers and help customers avoid disappointments, which are far from rare.

Osaka Air - the best choice for most people

Amid all the confusion around the H1–H5 labels, it makes sense to choose a product engineered to meet the needs of every user as well as possible. That’s exactly how the Osaka Air mattress was created—built on research into sleep ergonomics.

Its firmness is around 6.5/10, right in the sweet spot. Thanks to modern materials, the Osaka Air mattress adapts to the body’s shape without a suction/sinking effect, while providing stable spinal support throughout the night. There’s no guessing whether an H3 mattress from manufacturer A is the same as an H3 mattress from manufacturer B.

This solution is especially for sensible customers who are tired of vague labels and simply want to sleep well. If you’re looking for the best mattress that eliminates all doubts tied to the firmness scale, choose the Osaka Air mattress and see what a true standard of sleep comfort feels like.

We also encourage you to explore other articles on the best sleep and health blog, as well as the Encyclopedia of Healthy Sleep prepared by the ONSEN® team of specialists. For those who care about spine health, we recommend a set of spine exercises prepared by our physiotherapist.

FAQ: H3 mattress firmness

Which mattress is better, H3 or H4?

In principle, an H3 mattress should be medium firm, which makes it the best choice for almost everyone. However, in reality H3 and H4 mattresses may not differ much, because this scale is not standardized. The safest starting point is a truly medium firmness of about 6.5/10, which suits the vast majority of people. Slightly firmer support can make sense mainly for a small group of stomach sleepers who are also relatively young and athletic.

Which mattress is better, H2 or H3?

Nominally, an H2 mattress should be softer and an H3 mattress medium firm, but these are only internal labels used by stores or manufacturers. The firmness scale is not standardized yet. If you?re choosing blindly, aiming for a real medium firmness of around 6.5/10 is usually wiser than relying on the H2 or H3 tag. The best way is to confirm it with a home trial, because the labels don?t tell the full story.

Is an H3 mattress good?

It can be excellent if H3 really translates into a medium firmness close to 6.5/10 and if the construction makes sense. That means a mattress without memory foam as the top layer and with durable high-resilience foams that provide stable body support.

What does it mean when a mattress has firmness H3?

It?s only a conventional symbol. The same H3 mattress from two brands can be completely different, since the industry does not express firmness in objective physical units. In practice, it?s worth asking for the foam parameters and relying on real user testing. ONSEN? is probably the only company that provides full foam specifications and mattress composition, and additionally offers as many as 100 nights for testing.

How does the mattress firmness scale work?

The Polish firmness scale with the letter H is not standardized, so it doesn?t allow for reliable model comparison. Ideally, it should be based on measurements in newtons or kilopascals. For everyday communication, it?s often easier to describe firmness on the American 1?10 scale, where around 6.5/10 is the sweet spot.

Contents
Lack of standardization in the H1, H2, H3, H4…
H3 mattress firmness in practice
Universal firmness - there is a sweet spot
Differences in perceived mattress feel
The need to standardize the scale
Osaka Air - the best choice for most people
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