How firm should your mattress be? A guide by sleeping position
4 min read · Updated 25 September 2026
Side, back, stomach or all over the place: the firmness that usually suits each sleeping position, and what to do if you and your partner disagree.
Why position matters
The goal is to keep your spine roughly straight. Where your body is widest and heaviest decides how much the mattress needs to give.
Side sleepers
Your shoulder and hip press into the mattress, so they need room to sink in. A medium-soft to medium feel usually works best. Too firm and you wake with a sore shoulder.
Memory foam that cradles shoulders and hips · Medium-soft
Extra-soft, sink-in comfort · Plush
Back sleepers
You need support under the lower back without sinking at the hips. Medium to medium-firm suits most back sleepers.
Natural latex with a memory-quilted top · Medium
High-resilience foam for everyday family use · Medium-firm
Memory foam comfort on a firm base · Medium-firm
Stomach sleepers
Your hips sink first, which bends the lower back. A medium-firm to firm mattress keeps you flatter.
A cool glace cotton cover, soft top, firm core · Medium-firm
High-density foam for firm, even support · Firm
Combination sleepers and couples
If you change position through the night, a medium mattress that responds quickly, such as latex or springs, makes turning easier. Couples with different preferences usually meet at medium; pocket springs stop one person's movement waking the other.
Moulded foam that spreads your weight evenly · Medium
Pocket springs, so a partner turning over does not wake you · Medium
Still unsure?
Body weight changes things too: heavier people often prefer one step firmer, lighter people one step softer. The sleep quiz takes all of this into account in four questions. If you have a back or joint condition, ask your doctor what they recommend.
Still deciding?
Four questions, one recommendation, with the reasons.