Firm or soft mattress? Which firmness to choose according to your weight
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In short
Not too firm, not too soft: for most adults, what works is a firm mattress that allows the shoulders and hips to sink in slightly, with medium-firm or firm firmness and a comfort layer. The heavier you are, the firmer you need; if you sleep on your side, you need a little more comfort. At Morfeo, the Original Hybrid (firm firmness with comfort) is our default recommendation, and the Altus (medium-firm) if you want it a little less firm.
By the Morfeo team · manufactured in Yecla (Murcia) · updated on October 11, 2026
In this guide
- Firmness is not the same as support
- Is a firm or soft mattress better?
- Mattress firmness according to weight and sleeping position
- How materials affect firmness
- Signs that your mattress is not the right firmness
- If you and your partner weigh very differently
- The firmness of each Morfeo mattress
- Which mattress to choose based on your profile
- Trial, warranty, and delivery
- Frequently asked questions
Firmness is not the same as support
They are two different things, and mixing them up is the cause of almost all bad purchases:
- Firmness is what you feel when you lie down: whether the surface gives way a lot or very little. It is a sensation.
- Support is what the core does over hours: keeping the hips, which are the heaviest part, from sinking more than the chest and keeping the spine aligned.
A good mattress does both at the same time. A firm core supports the hips, while a comfort layer allows the shoulder to sink in slightly and fills the lumbar curve. That is why at Morfeo we talk about "firm firmness with comfort": firm where it supports, gentle where you touch it.
Is a firm or soft mattress better?
The idea that "the firmer, the better for your back" is very widespread, but both extremes have problems:
| Very soft | Medium-firm or firm firmness with comfort | Very firm | |
|---|---|---|---|
| Spine | The hips sink and the back is left in a "hammock" | Stays aligned | May stay straight, but without support for the lumbar curve |
| Shoulders and hips | Adapt well | Sink in just enough | Get overloaded: pressure points |
| Moving in bed | It is difficult; you feel trapped | Easy | Easy, but you toss and turn more looking for a position |
| Sensation | Cloud | Stable and comfortable | Board |
| May suit | Lightweight people who sleep on their side | Most adults | Almost no one as a first choice |
If your problem is back pain, the sensible thing is to look for firm support with comfort, not the firmest mattress possible. We explain this in the mattress for back pain guide. And if the pain persists, consult your doctor or physiotherapist: a mattress helps you rest better, but it is not a treatment.
Mattress firmness according to weight and sleeping position
There are two variables that decide almost everything: how much you weigh and which position you spend the most hours in. The heavier you are, the more the mattress sinks and the firmer you need it to keep the hips from dropping. And the wider the support area (on your side, the shoulder), the more comfort you need on top.
This table is a general guideline, not a rule. It is not based on a study: use it to narrow down your options, and then let your body decide during the trial.
| Your weight | On your side | On your back | On your stomach |
|---|---|---|---|
| Under 60 kg | Medium | Medium | Medium-firm |
| From 60 to 80 kg | Medium or medium-firm | Medium-firm | Medium-firm or firm |
| From 80 to 95 kg | Medium-firm or firm with comfort | Firm with comfort | Firm |
| Over 95 kg | XL mattress, with reinforced core, in any position | ||
How to read it:
- On your side is the position that requires the most comfort: the shoulder must sink in so that the neck and spine stay straight. If you sleep this way, also check the mattress for side sleepers guide.
- On your stomach is the one that requires the most firmness: if the mattress gives way, the lumbar area arches.
- If you change positions, stick with the position you spend the most hours in and choose a material that lets you turn over easily.
The weight rule at Morfeo
All our mattresses are guaranteed up to 95 kg per person. If you weigh more, the model for you is the Morfeo XL Mattress, designed for people over 100 kg. It is not a matter of taste: a core that is not designed for that weight will give way sooner. You can find more details in the mattresses for overweight people guide.
How materials affect firmness
Two mattresses with the same firmness on the product page may feel different because of the material of the top layer:
- Memory foam. It gives way slowly and adapts. It gives a hugging sensation and relieves pressure, even if the mattress is firm.
- Latex. Elastic: it gives way and bounces back. It feels more "alive" and makes it easier to move. We explain this in the natural latex mattresses guide.
- Pocket springs. Each spring works separately: it supports where there is more weight and gives way where there is less. It is the core of all our adult home mattresses.
- Hybrids. Pocket springs at the bottom for support and foam or latex on top for comfort. It is the most direct way to achieve "firmness with comfort".
And do not forget what is underneath: a sagging bed base makes any mattress feel soft. A firm and well-maintained base, such as the upholstered bases or the Morfeo storage beds, maintains the firmness just as it leaves the factory.
Signs that your mattress is not the right firmness
You wake up with a strained lumbar area
The hips sink more than the chest. You will also notice it if you find it difficult to turn over or get out of bed, or if you sleep better away from home.
Your arm or hand falls asleep
Especially when sleeping on your side: the shoulder does not sink in and gets overloaded. Another sign: you toss and turn all night looking for a position.
You see a dip where you sleep
It is not firmness: it is a mattress that has lost support. That is when you need to replace it, whether it feels firm or soft. We explain this in the problems of sleeping on an old mattress.
A new mattress needs a few weeks to adapt: it may seem firmer than it is during the first few days. That is why it makes sense to try it at home calmly and not decide in five minutes in a store.
If you and your partner weigh very differently
Choosing an intermediate firmness "so we are both okay" usually does not work. A construction that responds differently on each side works better:
- Pocket springs. Each spring sinks according to the weight it receives, so each person has their own support and you notice the other person's movements less.
- Choose based on the heavier person if one of you weighs over 95 kg: in that case, the XL for the bed.
- Two joined single mattresses if preferences are very different. Two 90 cm mattresses fit on a 180 cm bed. If you ask us, we adapt each of the two mattresses to the person who will sleep on it and their weight.
We explain this in the best mattress for couples guide.
The firmness of each Morfeo mattress
Grouped from least to most firm according to the product page of each model (within the same group, the order does not indicate that one is firmer than the other):
| Model | Firmness | How it feels | Price |
|---|---|---|---|
| Juvenil Lite | Medium | For children and teenagers from 4 to 18 years old. High-density HR core and 4 cm memory foam layer | See price |
| Nature | Medium | The most comfortable: soft when you lie down and firm where your back needs it. Natural latex and organic cotton on pocket springs | See price |
| Altus | Medium-firm | A little less firm than the Original Hybrid. More than 2000 pocket micro-springs and natural linen fabric | See price |
| Original Hybrid | Firm with comfort | The most chosen. More than 2000 pocket micro-springs and memory foam that relieves shoulders and hips: a straight back without sleeping on a board | See price |
| VisCool | Firm | Pocket springs and temperature-regulating layer. For those who want firmness and are hot | See price |
| Morfeo XL | Firm, reinforced structure | For people over 95 kg. Pocket springs and high-density foam | See price |
The price of each model changes according to the size: you can find it updated on its product page. If you are looking for a firm mattress, you can find them together in the firm mattresses collection.
Which mattress to choose based on your profile
Original Hybrid
Adult up to 95 kg who wants a firm mattress without sleeping on a board. Firm firmness with comfort and a removable cover washable at 30 °C. As of 25/09/2026, 114 reviews with an average of 4.81/5.
Altus
You sleep on your side or weigh very little and the Original Hybrid seems too firm to you. Medium-firm firmness, 28 cm and natural linen. As of 25/09/2026, 35 reviews with an average of 4.94/5.
Morfeo XL
For you or for the person who shares a bed with you if they weigh over 95 kg. Reinforced structure and firm firmness, designed for over 100 kg.
Are you looking for the opposite, a more comfortable mattress? The Nature is the medium firmness one. What if it is for a child or teenager? The Juvenil Lite, also medium firmness. All reviews are on the customer reviews page.
Firmness is tested by sleeping
Mattress trial, warranty, and delivery
- 100-night trial. No minimum number of nights: if the firmness is not right for you, return it and we will pick it up for free.
- 10-year warranty. Covers manufacturing defects.
- Delivery in 3-7 business days on the mainland.
- Free shipping on the mainland.
The 100-night trial only covers the mattress. We manufacture to order in Yecla (Murcia). More details on how the 100-night trial works.
Frequently asked questions
Which is better, a firm or soft mattress?
For most adults, neither extreme. A very soft mattress allows the hips to sink and the back to be left in a hammock; a very firm one overloads the shoulders and hips. What usually works is a firm mattress with a comfort layer: medium-firm or firm firmness, depending on your weight and position.
Is a firm mattress better for your back?
A firm mattress with comfort usually supports the spine better than a soft one, but firmer is not always better: if it does not allow the shoulders and hips to sink in, it creates pressure points. If you have persistent back pain, consult your doctor or physiotherapist.
What mattress firmness do I need according to my weight?
As a general guideline: under 60 kg, medium firmness; between 60 and 80 kg, medium-firm; between 80 and 95 kg, firm with comfort. Adjust it with your position: on your side, a little more comfort; on your stomach, a little more firmness. If you weigh over 95 kg, at Morfeo the XL Mattress is for you.
Which mattress do I need if I weigh over 95 kg?
All Morfeo mattresses are guaranteed up to 95 kg per person. Above that, the model for you is the Morfeo XL Mattress, with reinforced structure and designed for people over 100 kg.
What firmness is best for side sleeping?
Sleeping on your side requires more comfort, because the shoulder must sink in slightly so that the spine stays straight. Medium or medium-firm firmness usually fits, such as the Altus from Morfeo. If you weigh more, a firm firmness with a good comfort layer, such as the Original Hybrid.
How long does it take for the body to get used to a new mattress?
Normally a few weeks. During the first few days, a new mattress may seem firmer than it is. That is why at Morfeo you have 100 nights of trial without a minimum number of nights.
Which Morfeo mattress is the firmest and which is the softest?
The firm firmness ones are the Original Hybrid (firm with comfort), the VisCool, and the XL (reinforced structure for over 95 kg). The Altus is medium-firm firmness. The most comfortable ones are the Nature and the Juvenil Lite, both medium firmness.
If you are between firm and soft, start with firm with comfort
It is what works best for most adults. And if it is not for you, you have 100 nights to change your mind.
