Firmness is the most misunderstood part of mattress shopping. Brands use a vague 1-to-10 scale that is not standardized, so one company's medium can feel like another's firm. What actually matters is matching firmness to your sleep position and body weight.

Why position matters Your spine wants to stay neutral all night. Different positions load the mattress differently, so the right firmness keeps everything aligned.

  • Side sleepers need give at the shoulders and hips, so a softer-to-medium feel prevents pressure points
  • Back sleepers do well with medium to medium-firm, enough contour for the lower back without sagging
  • Stomach sleepers need firm support to stop the hips sinking and over-arching the spine

Why body weight matters Firmness is relative to the force pressing on it. A heavier person compresses foam more, so a bed rated medium will feel softer to them and firmer to a lighter sleeper.

  • Under about 130 pounds: most beds feel firmer, so lean one step softer than the label suggests
  • Around 130 to 230 pounds: standard ratings apply fairly accurately
  • Over about 230 pounds: choose firmer and prioritize strong support layers and durability

The safe default If you sleep in multiple positions or share the bed with someone of a different size, a medium-firm mattress is the most forgiving choice. It supports the majority of sleepers reasonably well and is the firmness most likely to satisfy two people at once. Use the trial period to confirm it works for your body.