Why firm

We stopped stocking anything softer than a 7.

Four reasons, and the case against each one. Firmness is not a mood we assign, it is the number the support core holds under load.

The range we sell

Firmness runs 1 to 10. We stock the top four and nothing below them, so the choice on this site is which firm, not whether firm.

1 to 6 · We do not stock this 7 to 10 · Every mattress we sell

Reason 1

It holds your spine in line

A support core that gives way lets the hips drop below the shoulders, and the spine spends the night bent. Firmness is not about a hard surface. It is about the core holding its shape under load while the layer above it handles how the bed feels.

This is why we publish what the core is made of on every product page rather than describing the feel and leaving it there.

Knit cover

Comfort layer

Support core, KITA Solid Foam

Reason 2

It keeps its shape

KITA Solid Foam was tested by TÜV Rheinland LGA to EN 1957:2012. A 1400 N load, about 143 kg, was rolled over it for 30,000 cycles, which is 60,000 strokes, equal to roughly ten years at eight hours a night. It lost 0.16 inch of height.

Our guarantee triggers at 1 inch of sag on a non-spring mattress, so the tested result sits well inside the threshold we replace against.

Read the full results →

Tested loss, 0.16 inch

Guarantee triggers at 1 inch

Drawn to scale. The gap is the margin we replace against.

Reason 3

It is built for heavier frames

A heavier body compresses any core further. Starting firmer is what keeps the support layer working rather than bottoming out.

Under 60 kg	7	Least compression, so the core can start lower.
60 to 80 kg	8	The middle of our range.
80 to 100 kg	9	The core has to resist more before it settles.
Over 100 kg	10	Start at the top or the support layer bottoms out.

These are the starting ratings our Firmness Finder uses. Side sleeping subtracts one.

Reason 4

You can soften a firm mattress, you cannot firm a soft one

Add a topper to a firm bed and the feel changes by the afternoon. Try the reverse and nothing happens, because putting something on top of jelly does not make the jelly solid. Buying firm keeps both options open.

See toppers →

Topper on top Firm core

Works

Topper on top Soft core

Still sinks

The other side of it

Firm is not for everyone.

We sell one kind of mattress, so we are the wrong shop for some people. Here is who, in our own words, before you spend the money.

Side sleepers under 60 kg

Our own tool steps you down to a 7, not a 9. At 9 or 10 your shoulder carries the load instead of the mattress. Buy the 7, or buy a 9 and a topper.

Anyone who wants to sink in

If the feeling you are buying is being enveloped, nothing in our range will give it to you. That is a plush pillow-top, and we do not sell one.

Anyone recovering from an acute injury or flare-up

Talk to a clinician about your own case before you take advice from a mattress company. A firm core suits most spines, not every spine.

Anyone replacing a bed they already liked

If your current mattress works and it is softer than a 7, we are not the upgrade. Rotate it and keep it.

Fair questions

The six objections we hear most, answered with the honest answer rather than the flattering one.

Will it hurt my shoulders and hips if I sleep on my side?

It can, if you buy too high a rating. Side sleeping puts the shoulder and hip in contact with the surface first, so they need a little give. Our own Firmness Finder subtracts one from your rating if you sleep on your side, which is why a lighter side sleeper lands on 7 rather than 9. If you are a side sleeper and you want a 9 or a 10 for durability, put a topper on it. That is the correct answer, not a workaround.

Is firm bad for back pain?

Very hard is. The trial evidence generally favours medium firm over very hard for chronic low back pain, and we are not going to pretend otherwise to sell a 10. What the evidence supports is alignment, which means a core that holds its shape rather than a surface that feels hard. A sagging soft mattress and a rock hard one fail in opposite directions. Most people with back pain should be looking at 7 or 8, not 10.

Will I get used to it, and how long does that take?

Usually two to three weeks. A new surface changes where your weight is carried, and the first few nights often feel worse before they feel better. This is why we ask you to give it a fortnight before making a judgement. If it is still wrong after a month, it is wrong, and no amount of adjusting will fix it.

Is firm just a cheaper mattress with less material in it?

It can be, and that is a fair suspicion. Height is the cheapest thing to add to a mattress, usually by adding air to the foam, so a thick soft bed can contain less material than a thin firm one. What you should ask for is density and what the core is made of. Ours is published on every product page: KITA Solid Foam is 20% lightweight aggregate and 80% high-density polyurethane, with no rebond content. Rebond is scrap foam from old mattresses bonded back together, and it is the cheap route we do not take.

What if I buy firm and hate it?

Add a topper and the feel changes the same afternoon. That is the practical reason to start firm. Beyond that, read our returns terms before you order rather than after, because a mattress that has been slept on is not a simple return for anyone in this industry, and we would rather you knew that upfront.

Is very firm the same as sleeping on the floor?

No, and we would not recommend the floor. A 10 out of 10 core still compresses and still redistributes load across your body. A floor does neither. The distinction is that a firm core resists sinking while continuing to support, which is the property we test for. If the floor were a good mattress we would have a much simpler business.