Mattress Firmness Scale Explained (1-10)

By MattressDealsOnline Editorial · Updated July 2026

Firmness is the first number every mattress brand puts in front of you, and it's the one most likely to make or break your sleep. But the 1-10 scale is fuzzier than it looks: there's no industry standard behind it, the same number can feel different from brand to brand, and - most importantly - a rating measured in a lab feels different once your specific body is lying on it. This guide explains what the numbers actually mean and how to find yours.

What the 1-10 firmness scale means

Firmness describes how hard or soft a mattress feels when you first lie down - specifically how much you sink in before the bed pushes back. It is not the same thing as support, which is about keeping your spine aligned. A soft bed can be supportive and a firm bed can be unsupportive; firmness is just the initial feel. Here's how the scale breaks down in practice:

• 1-2 (Very soft): Rare in production beds. You sink in deeply with almost no pushback. Too little support for most people.
• 3-4 (Soft): Noticeable sink and a plush hug. Suits lightweight side sleepers who need the shoulder and hip to settle in.
• 5-6 (Medium): A balance of cushion and support. The comfort zone for many side and combination sleepers, and average-weight bodies.
• 6-7 (Medium-firm): The most popular range and the safest all-round choice. Supportive with just enough give. Where most best-sellers live.
• 7-8 (Firm): You rest more on top of the bed than in it. Suits back and stomach sleepers and heavier bodies who need the hips held up.
• 9-10 (Very firm): Very little give, a floor-like feel. A niche preference and useful for some heavier stomach sleepers.

One thing worth knowing up front: there is no official body that certifies these numbers. Each brand rates its own beds, so one company's "medium-firm 6" can feel like another's 7. Independent testing labs exist partly to correct for this, which is why the firmness positions in the chart above come from lab testing rather than the numbers printed on the box.

Why the same mattress feels different to different people

This is the single most misunderstood thing about firmness, and it's why one rating can't serve everyone: firmness is perceived relative to your body weight. A firmness rating is measured with a standardized weight pressing into the mattress. Your body applies a different amount of force, so the same bed genuinely feels different depending on how much you weigh.

• Under 130 lb: You don't press into the comfort layers as far, so every mattress feels firmer than its rating. A "medium 6" can feel like a 7. Lighter sleepers usually want to size down a point toward softer.
• 130-230 lb: You're close to how beds are rated, so the printed number is roughly what you'll feel. This is the reference range most ratings assume.
• Over 230 lb: You compress the bed further, so it feels softer than its rating. A "medium-firm 6.5" can feel like a 5. Heavier sleepers usually want to size up a point or two toward firmer.

The practical rule: take the standard advice for your sleep position, then add a point if you're heavier or subtract a point if you're lighter. We cover the heavier end in depth in our firmness guide for heavier sleepers.

Matching firmness to your sleep position

After body weight, your sleep position is the biggest factor - because different positions put pressure on different parts of your body and need different amounts of give.

• Side sleepers want softer, roughly 4-6. Lying on your side concentrates weight on the shoulder and hip, so those points need to sink in to relieve pressure. Too firm and you wake with a sore shoulder or numb arm.
• Back sleepers want medium-firm, roughly 6-7. You need the lumbar region supported so the lower back doesn't arch, with just enough cushion to fill the curve of your spine.
• Stomach sleepers want firm, roughly 7-8. This is the position most prone to back strain, because a soft bed lets the hips sink and bows the spine. A firm surface keeps the midsection lifted.
• Combination sleepers want medium to medium-firm, roughly 5.5-6.5. A middle firmness with a bit of responsiveness makes it easier to change positions without feeling stuck.

Where body weight and position disagree - say, a heavier side sleeper - split the difference: the heavier side sleeper who'd normally want a 5.5 should look closer to 6.5, firm enough to hold the hips but still soft enough to relieve the shoulder.

Firmness is not support - don't confuse the two

The most common firmness mistake is assuming a firmer bed is automatically more supportive. They're different properties. Firmness is how the surface feels; support is whether the bed keeps your spine in a neutral line all night. A plush mattress with a strong support core can hold your spine beautifully while feeling soft on top. A cheap firm mattress can feel hard yet still let your hips sag over time as the materials break down.

This distinction matters most for back pain. It's tempting to reach for the firmest bed you can find, but the research consistently points to medium-firm as best for most back-pain sufferers - supportive enough to keep the spine neutral, cushioned enough to relieve pressure. What you actually want is good support at a comfortable firmness, not maximum firmness. If back pain is your main concern, our guide to spotting a too-firm or too-soft bed walks through the warning signs.

How firmness relates to mattress type

Firmness and construction are linked but independent - you can find most firmness levels within each mattress type, but the type shapes how that firmness feels. Memory foam at a 6 feels different from a hybrid at a 6: the foam gives a slow, sink-in version of medium-firm, while the hybrid gives a springier, more "on top" version of the same number. If you're weighing materials as well as firmness, see our breakdowns of memory foam vs hybrid and memory foam vs latex.

What if the number is wrong once it arrives?

Firmness is the main reason mattress brands offer sleep trials - because you can't fully know how a bed's firmness suits you until you've slept on it for a few weeks. Two honest points here. First, give it time: new mattresses often feel firmer out of the box and soften slightly as the comfort layers break in, so most trials ask for a break-in period before returns. Second, small mismatches are fixable - a topper can soften a too-firm bed or add support to a too-soft one - but a large mismatch usually means the bed is wrong for you, and that's exactly what the trial period is for. We explain how those windows work in our guide to trial periods and return fees.

Softer beds we've tested (medium and below)

Firmer beds we've tested (7 and up)

FAQ

What firmness is best for most people?

Medium-firm, around 6 to 6.5 out of 10, suits the widest range of sleepers. It supports the spine while still cushioning pressure points, which is why most best-selling beds land there.

Does my body weight change what firmness I need?

Yes, significantly. Heavier bodies compress a mattress further, so it feels softer than its rating - add a point or two. Lighter bodies feel a bed as firmer than rated, so subtract a point or so.

Is a firmer mattress better for your back?

Not necessarily. Research points to medium-firm, not maximum firm, as best for back pain. The goal is a neutral spine, which needs support and cushioning together, not a hard board.

Can you soften or firm up a mattress you already own?

Somewhat. A mattress topper can soften a too-firm bed or add support to a too-soft one, and a firmer foundation can make a bed feel marginally more supportive. Neither fully overrides the mattress itself.