Why Mattress Firmness Scales Aren't Standardized
There is no industry-standard mattress firmness scale. Each brand assigns its own 1-10 number or Soft/Medium/Firm label internally, calibrated only against its own product lineup, with no accredited third party auditing or standardizing it across brands. The closest thing to an objective measurement — ILD — is a raw materials-testing figure, not a mattress-industry certification of the finished product.
The one thing to know: A brand's '1-10' firmness number or 'Soft/Medium/Firm' label is entirely self-assigned — there is no industry body auditing it, no standard scale it's measured against, and no requirement that a '6' from one brand feel anything like a '6' from another. Two 'medium-firm' mattresses from different brands can differ enormously in actual feel. Treat every brand's number as a claim within that brand's own lineup, not a cross-brand measurement.
What exists instead of a standard scale
- ILD (Indentation Load Deflection) — a defined foam-industry test for a single layer's firmness, disclosed by only a minority of brands. See What Is ILD?
- A brand's own Soft/Medium/Firm or 1-10 lineup label — internally consistent within that brand, not standardized against others.
- Third-party reviewer scores — one review site's subjective panel score on its own scale, also not standardized against other review sites or against ILD.
How to compare firmness across brands anyway
Look past the number or word to the underlying facts where they're disclosed: published ILD for the comfort layer and support core, construction type, and comfort-layer thickness. Where those aren't disclosed, treat the brand's own label as informative only about that brand's own lineup — see the Firmness Translation Index for which brands actually disclose ILD.
Frequently Asked Questions
Because there isn't an industry-standard firmness scale. Each brand assigns its own 1-10 number or Soft/Medium/Firm label internally, calibrated only against its own product lineup, with no accredited third party auditing or standardizing it across brands.
Not for the subjective firmness label itself. The closest thing to an objective, standardized measurement of a foam layer's firmness is ILD (Indentation Load Deflection), a defined foam-industry test — but it's a raw materials-testing figure, not a mattress-industry certification of the finished product's overall firmness.
Look past the number or word to the underlying facts where they're disclosed: published ILD for the comfort layer and support core, construction type, and comfort-layer thickness. Where those aren't disclosed, treat the brand's own label as informative only about that brand's own lineup.
They can add a useful independent data point, but they typically reflect one reviewer panel's subjective impression on their own site-specific scale, which also isn't standardized against other review sites or against ILD. Cross-referencing multiple sources plus any disclosed specs is more reliable than any single number.