Mattress firmness is one of the most important factors in how well you sleep — and one of the most misunderstood. "Firmer is better for your back" is a myth. So is "softer means more comfortable." The right answer depends entirely on you: how you sleep, how much you weigh, and what actually feels good.
This guide cuts through the confusion and gives you a clear framework for choosing the right firmness level.
Most mattresses are rated on a 1–10 scale, where 1 is the softest and 10 is the firmest. In practice, nearly all mattresses fall between 3 and 8.
| Firmness Level | Description | Best For |
|---|---|---|
| 1–3 (Soft) | Deep sink, heavy contouring | Side sleepers, lighter body weights |
| 4–5 (Medium-Soft to Medium) | Balanced feel, moderate contouring | Side and combo sleepers, average weight |
| 6 (Medium-Firm) | Slight give, strong support | Back sleepers, most sleepers — the most popular setting |
| 7–8 (Firm) | Minimal sink, solid surface | Stomach sleepers, heavier body weights |
| 9–10 (Very Firm) | Nearly no give | Rare — specific medical or preference needs |
Note: Firmness is not the same as support. A soft mattress can still be supportive. A firm mattress can still feel uncomfortable if it doesn't match your body type.
Your sleep position determines where pressure concentrates on your body. That's the starting point for any firmness decision.
Side sleeping creates sharp pressure points at the shoulder and hip. A softer surface lets those joints sink in slightly so the spine stays level. Most side sleepers do best on a medium to medium-soft mattress (3–5 range).
Back sleeping spreads body weight across the widest surface area, so pressure is less concentrated. The lumbar region needs support without gap. Most back sleepers do best on a medium-firm mattress (5–7 range).
Stomach sleeping already puts strain on the neck and lower back. A soft mattress makes this worse by allowing the midsection to sag. Most stomach sleepers need a firm mattress (6–8 range) to keep the spine level.
If you switch positions throughout the night, look for a medium to medium-firm mattress that performs reasonably well in multiple positions. Hybrid and latex mattresses often excel here due to their responsive feel.
Body weight changes how any mattress actually feels. A mattress labeled "medium" may feel soft to a heavier person and firm to a lighter one.
| Body Weight | How Mattresses Feel | Recommended Firmness |
|---|---|---|
| Under 130 lbs | Mattresses feel firmer than rated | Soft to medium-soft (3–5) |
| 130–230 lbs | Close to rated feel | Match to sleep position above |
| Over 230 lbs | Mattresses feel softer than rated | Medium-firm to firm (6–8); look for higher-density foam or coil support |
Heavier sleepers also need to pay close attention to durability — softer foams compress faster under more weight. Look for high-density base foams or pocketed coil systems.
This is one of the most common mattress challenges. If one person is a side sleeper who wants soft and the other is a back sleeper who needs firm, a standard single-firmness mattress is a compromise for both.
A few practical options:
| Firm Mattress | Soft Mattress | |
|---|---|---|
| Feel | Solid, minimal sink | Plush, body-contouring |
| Best sleep position | Stomach, back | Side |
| Body weight | Better for heavier sleepers | Better for lighter sleepers |
| Spinal alignment | Strong neutral alignment | Good if firmness is correct |
| Pressure relief | Less cushioning at joints | More cushioning at shoulders/hips |
| Heat retention | Generally sleeps cooler | More foam = more heat (varies by model) |
| Edge support | Typically better | Can feel unstable at edges |
| Durability | Often lasts longer | Softer foams may compress faster |
| Motion isolation | Decent | Better (especially memory foam) |
If you're not sure, start with medium-firm. It's the most versatile firmness level — supportive enough for back sleepers, with enough give for side sleepers at average weight. It's the most popular rating for a reason.
The best way to know for sure? Try it in person. Spend 10–15 minutes lying on a mattress in your actual sleep position. That tells you far more than any online description.
Firmness and mattress type are separate decisions. You can get a soft or firm version of most mattress types:
Browse our full mattress collection or visit any of our 5 LA showrooms to test different types and firmness levels side by side.
Not automatically. A firm mattress is better for back sleepers and stomach sleepers who need to prevent hip sinkage. Side sleepers often experience more back pain on a mattress that's too firm, because the hips and shoulders can't sink in enough to keep the spine level.
They can — but usually only when they're the wrong firmness for your sleep position or body weight, or when they've worn out and lost their support. A properly matched soft mattress doesn't cause back pain.
Too firm: You wake up with pressure points — shoulder, hip, or knee pain — or your lower back feels tense. Too soft: You wake up with lower back ache, or you feel like you're "stuck" and struggling to change positions at night.
Yes — and you should. Visit any of our LA Mattress Store locations and lie on different firmness levels in your actual sleep position for several minutes each. Our staff can help narrow down options based on your sleep habits and preferences. All purchases also come with our 120-night comfort guarantee, so if the feel isn't right, you can exchange it.
Medium-firm is the safest default for a guest room because it works reasonably well for most sleep positions and body types.
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