What Mattress Firmness Means
Firmness describes how hard or soft a mattress feels when you first lie on it: how much it gives, and how quickly you meet resistance. It is not the same as support. Support is how well a mattress keeps your spine aligned, which depends on the core (coils, latex or dense foam). A soft mattress can still be supportive, and a firm mattress can be unsupportive if it sags.
Most brands describe firmness on a 1 to 10 scale. The labels are not standardized, so treat them as a guide and compare within a brand rather than across brands.
The Firmness Scale
| Scale | Label | How It Feels | Usually Suits |
|---|---|---|---|
| 1 to 2 | Extra soft | Deep sink, very little resistance | Rare; very light side sleepers |
| 3 to 4 | Soft | Noticeable sink and contouring | Lighter side sleepers |
| 5 | Medium | Balanced give and support | Side and combination sleepers |
| 6 to 7 | Medium-firm | Light cushioning, strong support | Back sleepers, many couples |
| 8 | Firm | Little sink, on-top feel | Stomach and heavier sleepers |
| 9 to 10 | Extra firm | Minimal give | Rare; specific preferences |
Where the Mattresses We Cover Sit
Approximate positions from independent reviewers' ratings; your feel will vary
Signature Bliss figures reflect independent reviewers' ratings (around 5 and 6 to 6.5). Aviya figures reflect third-party reviewers' ratings for its three models.
Firmness by Sleep Position
Side Sleepers: Soft to Medium (3 to 6)
The shoulder and hip need to sink in so the spine stays straight. Too firm, and those points take all the pressure.
Back Sleepers: Medium to Medium-Firm (5 to 7)
The lower back needs support so the hips do not sink below the shoulders, with enough give to fill the curve of the lower back.
Stomach Sleepers: Medium-Firm to Firm (6 to 8)
Firmer surfaces keep the hips level and reduce arching of the lower back.
Combination Sleepers: Medium (5 to 6)
A middle firmness and a responsive material, such as latex or coils, make changing positions easy.
How Body Weight Changes Firmness
Firmness ratings are usually based on average-weight sleepers. Your weight shifts the scale:
| Body Weight | Side | Back | Stomach |
|---|---|---|---|
| Under about 130 lb | 3 to 5 | 4 to 6 | 5 to 6 |
| About 130 to 230 lb | 4 to 6 | 5 to 7 | 6 to 7 |
| Over about 230 lb | 5 to 7 | 6 to 8 | 7 to 8 |
Heavier sleepers also benefit from taller mattresses and coil or air support, because they reach the core sooner. See our guide for heavier sleepers.
How Materials Affect Feel
| Material | Firmness Character |
|---|---|
| Memory foam | Softens with body heat; slow, hugging feel; feels firmer in a cold room |
| Latex | Consistent across temperatures; buoyant; firmness set by density (ILD) |
| Coils | Add push-back and bounce; zoned coils vary firmness across the body |
| Pillow tops | Make a supportive mattress feel softer on first contact |
| Air chambers | Adjustable; firmness changes with air pressure |
Understanding ILD
Some brands publish ILD (indentation load deflection), the force needed to compress foam or latex by a set percentage. Higher ILD means firmer. EcoTerra, for example, lists its Medium latex at ILD 24 to 26 and its Medium-Firm at 29 to 31, and Layla lists its Essential comfort foam at 9 ILD over 35 ILD support foam. ILD describes one layer, not the whole mattress, so it is most useful for comparing layers of the same material.
Firmness vs Feel: Two Different Things
Two mattresses with the same firmness rating can feel very different. A medium memory foam bed hugs you slowly; a medium latex bed pushes back quickly; a medium hybrid adds bounce. Decide on firmness from your position and weight, then choose the feel you prefer. Our latex vs memory foam guide covers the difference.
If You Can't Decide
- Choose medium-firm if you sleep in several positions; it is the most forgiving middle ground.
- Lean firmer if torn: a topper can soften a mattress, but nothing makes a soft mattress more supportive.
- Pick adjustable options: PlushBeds' 365-night comfort guarantee, Spindle's rearrangeable layers or Airpedic's adjustable air.
- Couples: consider split or dual firmness; see our couples guide.
Signs Your Mattress Is the Wrong Firmness
| Too Soft | Too Firm |
|---|---|
| Lower back aches after back or stomach sleeping | Shoulder or hip soreness after side sleeping |
| Feeling stuck or hard to turn over | Numb or tingling arm |
| Hips sinking below shoulders | Gap under the lower back when lying flat |
| Rolling toward a partner | Frequent tossing to relieve pressure |
The Break-In Period
New mattresses often feel a little firmer at first and soften slightly over the first few weeks as materials relax. Your body also needs time to adjust, especially if your old mattress was sagging. Wait three to four weeks before deciding a firmness is wrong, which is also why many trials require a minimum number of nights.
For our picks at each firmness, see the best mattress guide, the side sleeper guide and the back pain guide.
Mattress Firmness FAQ
What Is the Most Popular Mattress Firmness?
Medium to medium-firm, roughly 5 to 7 on a 10-point scale, suits the widest range of sleepers and is the most common choice.
Is a Firm Mattress Better for Your Back?
Not always. Very firm mattresses can create pressure points and gaps under the lower back. Medium-firm is often a better balance, depending on your weight and sleep position.
Why Does My Mattress Feel Firmer or Softer Than Advertised?
Firmness labels are not standardized between brands, and body weight changes how firm a mattress feels. Room temperature also affects memory foam, which softens when warm.
Can I Make a Firm Mattress Softer?
Yes, a soft topper can add cushioning. Making a soft mattress firmer is harder, because a topper cannot add support underneath.
What Does ILD Mean?
ILD, or indentation load deflection, measures how much force it takes to compress foam or latex by a set amount. Higher numbers mean firmer material.
Two Firmness Options, a Year to Decide
Our top pick, the PlushBeds Signature Bliss, comes in Medium or Medium-Firm with a 365-night comfort guarantee.
Check Signature Bliss Price