For most people, a medium to medium-firm mattress is the safest place to start. From there, your sleep position matters most. Side sleepers usually prefer a softer feel, stomach sleepers a firmer one, and back sleepers something in between. Body weight moves that up or down, because heavier people sink further into any mattress. If you share the bed and can't agree, a dual-firmness mattress lets you choose between two feels.
What does mattress firmness mean?
Firmness is how soft or hard a mattress feels when you lie on it. It's about the feel of the surface, which is a different thing from how well the mattress holds its shape over time.
There's no official Australian firmness standard. Most brands describe firmness on a 1–10 scale, roughly like this:
| Scale | Feel | What it feels like |
|---|---|---|
| 1–3 | Soft | You sink in noticeably |
| 4–5 | Medium-soft | Cushioned, with some sink |
| 5–6 | Medium | Balanced: some give, without sinking far |
| 6–7 | Medium-firm | You lie more on top than in |
| 8–10 | Firm | Very little give |
Treat any brand's rating as a guide, not a measurement. One brand's "medium" can feel like another's "medium-firm", so read how a mattress is described, not just the number.
Which firmness suits your sleep position?
Your usual sleep position is the biggest single factor. Think about the position you wake up in, not just the one you fall asleep in.
| Sleep position | Usual preference | Why |
|---|---|---|
| Side | Medium-soft to medium | Shoulders and hips are the widest points, so most side sleepers like enough give for them to sink in a little |
| Back | Medium to medium-firm | Most back sleepers like to lie fairly level, without the hips sinking far |
| Stomach | Medium-firm to firm | A softer mattress lets the hips sink below the shoulders, which most stomach sleepers find uncomfortable |
| Combination | Medium | A middle feel makes it easier to change position through the night |
Side sleepers
Most side sleepers prefer a medium-soft to medium mattress. When you lie on your side, your shoulder and hip carry most of your weight. On a very firm mattress, those points press into the surface and don't sink in. On a medium or softer mattress, they settle into it.
Back sleepers
Most back sleepers are comfortable on a medium to medium-firm mattress. You want enough cushioning to feel comfortable, while your hips stay roughly level with your shoulders rather than sinking below them.
Stomach sleepers
Stomach sleepers usually prefer the firmest feel of the four. Lying face-down puts your heaviest point, the hips, in the middle of the bed. A firmer mattress keeps you lying flatter.
Combination sleepers
If you move around, a medium feel is the easiest middle ground. It's soft enough on your side and firm enough on your back, and a mattress with some bounce makes it easier to roll over.
Does body weight change how firm your mattress should be?
Yes. The same mattress feels softer to a heavier person and firmer to a lighter one. Heavier bodies sink further into the comfort layers, so a "medium" can feel closer to soft. Lighter bodies barely sink, so a "medium-firm" can feel quite hard.
A simple rule:
- Lighter build: consider going one step softer than the position guide above.
- Average build: follow the position guide.
- Heavier build: consider going one step firmer.
The same applies to children. Kids are light, so a mattress that feels firm to an adult often feels comfortable to them.
What if you and your partner like different firmness?
Choose for the firmer sleeper, add a topper, or buy a mattress that has more than one feel. There are three ways couples usually handle it:
- Meet in the middle. A medium or medium-firm mattress is the most common compromise.
- Add a topper. Start with a firmer mattress and add a mattress topper to soften it. This softens the whole bed, though, not just one side.
- Buy a dual-firmness mattress. The Naptime 2.0 Dual Firmness has a medium-firm side and a firmer side, so you can switch between the two feels.
We cover this in more depth in the best mattress for couples with different firmness preferences.
Does pocket spring or foam change the feel?
Yes. Construction changes how a firmness feels, not just how firm it is.
- Pocket spring mattresses tend to feel more responsive, with more bounce, which makes it easier to move and change position.
- Memory foam mattresses tend to feel slower, and you sink into them more.
- Pillow-top and euro-top mattresses add a soft layer on top of the support, so they feel plusher on the surface.
For a full comparison, read pocket spring vs memory foam vs hybrid.
Which Naptime mattress matches which feel?
| If you want… | Look at | How it's described |
|---|---|---|
| A plush feel | Osteo Support | One of our plushest mattresses: a pillow-top over 3-zone pocket springs |
| Plush, but supportive | Optimal Support | 5-zone pocket springs with layers of foam |
| Medium-firm | Ortho Balance | 3-zone pocket springs with a medium-firm feel |
| Two feels in one mattress | Naptime 2.0 Dual Firmness | A medium-firm side and a firmer side |
Stock varies by size, so check the product page for the size you need.
What if I choose the wrong firmness?
Give a new mattress time before you judge it. Your body needs to get used to a different sleep surface, and a new mattress can feel different after a few weeks than it does on night one.
On eligible mattresses, the Naptime Goodnight Guarantee gives you time to find out. After 30 nights, if it still isn't right, our sleep support team will work with you to sort it out. See the Goodnight Guarantee page for the full terms and eligible models.
If a mattress turns out to be a little too firm, a topper is a cheaper fix than replacing it. If it's too soft, a topper won't help, because toppers only add softness.
Frequently asked questions
What mattress firmness is best for most people?
Medium to medium-firm is the most common choice and the safest starting point if you're unsure.
Is a firm mattress better for you?
Not automatically. Firmer isn't better. The right firmness depends on your sleep position, your body weight and what feels comfortable to you.
What firmness is best for side sleepers?
Most side sleepers prefer medium-soft to medium, so the shoulders and hips can sink in a little.
What firmness is best for stomach sleepers?
Most stomach sleepers prefer medium-firm to firm, so the hips don't sink below the shoulders.
Does a mattress get softer over time?
Most mattresses soften slightly as the comfort layers settle, especially in the first few weeks.
Can I make a firm mattress softer?
Yes. A mattress topper adds a softer layer on top. You can't make a soft mattress firmer with a topper, though.
What if my partner and I like different firmness?
Choose a medium or medium-firm compromise, soften a firmer mattress with a topper, or choose a mattress with more than one feel, like the Naptime 2.0 Dual Firmness.
Is firmness the same across brands?
No. There's no official Australian firmness standard, so a "medium" from one brand can feel different from another's.
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