Why weight changes firmness#
Firmness ratings are set against an average body, so the more you weigh, the further you compress a mattress and the softer it feels, while lighter sleepers experience the same bed as firmer. That's why weight is one of the most useful guides to the firmness you should buy. The general target for most people is medium-firm, which the evidence links to the best comfort, sleep quality and spinal alignment,1 with weight nudging you firmer or softer from there.
Mattress firmness by weight chart#
| Body weight | Side sleeper | Back sleeper | Front sleeper |
|---|---|---|---|
| Under 60 kg | Soft to medium | Medium | Medium to medium-firm |
| 60–90 kg | Medium to medium-soft | Medium to medium-firm | Medium-firm |
| 90–110 kg | Medium to medium-firm | Medium-firm | Medium-firm to firm |
| Over 110 kg | Medium-firm | Firm | Firm |
Treat this as a starting point, not a rule. It points you to the right zone; personal comfort and a home trial confirm the exact feel.
How to read the chart#
- Lighter sleepers need softer surfaces to compress the comfort layer enough for pressure relief, especially on the side.
- Average-weight sleepers sit closest to standard firmness ratings, so position matters more than weight.
- Heavier sleepers need firmer support to stop the hips sinking and the spine sagging, and benefit from robust cores that resist early softening.2
Position fine-tunes it#
Within your weight band, your sleeping position shifts the ideal: side sleepers go a notch softer (to cushion the shoulder and hip), front sleepers a notch firmer (to keep the hips lifted). For the full breakdown, see our sleeping position guide and body weight guide.
It still comes down to fit#
Charts narrow the shortlist, but comfort ultimately depends on the interaction between sleeper and surface, which is why preference and a trial matter.3
Browse by firmness and type or take our quiz for a personalised recommendation.
References#
- Caggiari G, Talesa GR, Toro G, Jannelli E, Monteleone G, Puddu L. What type of mattress should be chosen to avoid back pain and improve sleep quality? Review of the literature. Journal of Orthopaedics and Traumatology. 2021;22:51. doi:10.1186/s10195-021-00616-5
- Vlaović Z, Klarić N, Domljan D. Investigating the Impact of Long-Term Use on Mattress Firmness and Sleep Quality: Preliminary Results. Applied Sciences. 2024;14(21):10016. doi:10.3390/app142110016
- Robbins R, Quan SF, Barger LK, et al. Validation of the Boston Mattress Satisfaction Questionnaire. Frontiers in Sleep. 2025;4:1509420. doi:10.3389/frsle.2025.1509420
