The Firmness Translation Index
Mattress firmness is self-reported on a 1-10 scale that every brand defines differently. The objective underlying measure is ILD (Indentation Load Deflection) — the force needed to compress a standard foam sample 25% — but brands rarely publish it. This dataset lines up each mattress's self-reported label against its construction type, comfort-layer thickness, sleep-position fit, and ILD where a brand actually discloses it. Most rows read "Not disclosed" for ILD; that absence is the finding.
The one thing to know: ILD (Indentation Load Deflection) is a defined foam-industry test: the force, in pounds, needed to compress a standard 15"x15"x4" foam sample by 25% of its thickness using a 50-square-inch circular indenter (ASTM D3574 for polyurethane foam; latex is commonly tested under a related but distinct protocol). Higher ILD means firmer foam. The catch: almost no mattress brand publishes it, because unlike a self-reported '1-10' label, ILD is a verifiable number a buyer could use to compare brands directly — which is exactly why its absence is itself the story.
License & how to cite
License: CC BY 4.0 — free to use with attribution.
How to cite: Mattress Firmness Picks Editorial Team, "Firmness Translation Index" v1.0, https://mattress-firmness-picks.pages.dev/firmness-translation-index/, 2026.
The dataset
| Brand | Model | Self-reported firmness | Comfort-layer ILD | Support-core ILD | Construction | Comfort-layer thickness | Best-fit sleep position | Source class |
|---|---|---|---|---|---|---|---|---|
| Saatva | Classic – Plush Soft | Soft (~4/10) | Not disclosed | Not disclosed | Innerspring hybrid | ~2 in | Side, lighter body weight | Manufacturer spec sheet |
| Saatva | Classic – Luxury Firm | Medium Firm (~6/10) | Not disclosed | Not disclosed | Innerspring hybrid | ~2 in | Combination/back | Manufacturer spec sheet |
| Saatva | Classic – Firm | Firm (~8/10) | Not disclosed | Not disclosed | Innerspring hybrid | ~2 in | Stomach, heavier body weight | Manufacturer spec sheet |
| Brooklyn Bedding | Signature Hybrid | Medium | 18 (TitanFlex) | 28 (transition) | Hybrid | ~3 in | Combination | Manufacturer spec sheet |
| Brooklyn Bedding | Plank Firm (firm side) | Firm | 28 (fast-response) | 36 (1.8 lb base) | All-foam, flippable | ~2 in | Stomach, heavier body weight | Manufacturer spec sheet |
| Brooklyn Bedding | 3in Latex Topper – Soft | Soft (of topper lineup) | 19 | N/A (topper) | Natural Talalay latex | 3 in | Side (topper use) | Manufacturer spec sheet |
| Nectar | Original Mattress | Medium Firm (~6/10) | Not disclosed | Not disclosed | All memory foam | ~3 in | Side/back, budget | Retailer listing |
| Purple | Original Mattress | Medium-Firm | N/A (polymer grid) | Not disclosed | Polymer grid + support foam | 2 in (grid) | Back/stomach/combo | Manufacturer spec sheet |
| Casper | Original Mattress | Medium (~6-7/10) | Not disclosed (zoned) | Not disclosed | All-foam, zoned | ~4 in | Back/combo | Derived (brand + reviewer scores) |
| DreamCloud | Premier Rest Mattress | Medium Firm (~6.5/10) | Not disclosed | Not disclosed | Hybrid | ~3.5 in | Combination, budget hybrid | Retailer listing |
| Tempur-Pedic | TEMPUR-Adapt Medium | Medium | N/A (proprietary material) | Not disclosed | Proprietary viscoelastic + foam | ~3 in | Side/combo | Manufacturer spec sheet |
| Avocado | Green Mattress | Medium Firm (~6-7/10) | Not disclosed | Not disclosed | Latex hybrid | ~2 in | Back/stomach | Manufacturer spec sheet |
| Zinus | 12in Green Tea Memory Foam | Medium Firm–Firm | Not disclosed | Not disclosed | All memory foam | ~2.5 in | Side/back, budget firm | Retailer listing |
Reading the ILD columns
Most mattress brands publish a firmness label or 1-10 number but not the underlying ILD for any layer. When a brand DOES publish ILD (as Brooklyn Bedding does for several product lines), it's usually because the brand also sells raw foam/components to a more technical buyer audience, not because of any industry requirement. The absence of ILD on a spec sheet doesn't mean a mattress is low quality — it means the firmness claim can't be independently verified against another brand's claim. Identical ILD numbers feel different depending on construction. Memory foam has a slow, viscoelastic recovery that deepens the sink-in feeling at a given ILD; latex responds quickly and feels more buoyant at a comparable ILD; a hybrid's coil support core adds bounce and can make a soft comfort layer feel more supportive than the same foam over an all-foam base. So ILD is only directly comparable within similar constructions — a 28-ILD latex layer and a 28-ILD memory-foam layer will not feel the same. A "Not disclosed" cell is not a data gap on our end — we checked each brand's public product page and spec sheet; it means the brand itself does not publish that number.
Caveats — read before citing a number
- Self-reported firmness is not standardized across brands. 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.
- Body weight changes perceived firmness. Body weight changes how firm a given ILD or firmness label actually feels, because a heavier body compresses further into any given foam before reaching equilibrium. A lighter sleeper (under ~130 lb) sits nearer the top of a comfort layer and feels its true surface firmness; a heavier sleeper (over ~230 lb) compresses through the comfort layer into the firmer support core beneath, so the same mattress can feel noticeably softer to them than the label suggests. This is why firmness guides that ignore body weight are incomplete.
- ILD is only comparable within similar constructions. A 28-ILD latex layer and a 28-ILD memory-foam layer will not feel the same; some comfort layers (polymer grids, proprietary viscoelastic materials) aren't rated on the standard foam ILD scale at all.
- No health or medical claims. This dataset describes support and pressure-distribution equipment facts, never a treatment, prevention, or relief claim for back pain or any condition.
- Firmness labels can change per size or per revision. Brands periodically update product lines; always confirm the current spec on the brand's own page before buying.
Methodology & versioning
Version 1.0 — published July 30, 2026. Facts are drawn from each brand's own public product pages and spec sheets, cross-checked against third-party mattress-review aggregators (MattressNerd, NapLab, Sleep Foundation) where a brand's own page did not state a figure directly. We do not test mattresses ourselves; this is a specification and disclosure-facts reference, not a lab result. Corrections: if a brand updates a spec or we find an error, this page and both CSVs are updated in place and the version/date bumped — see How We Evaluate for our full editorial policy.
Machine-readable download: the current table is available as CSV at /firmness-translation-index.csv, with a version-pinned copy at /firmness-translation-index-v1.0.csv, and a condensed digest is maintained in /llms-full.txt.
This page is general reference information about mattress specifications and disclosure practices, not a health or medical determination for any individual.
Frequently Asked Questions
A normalized dataset that lines up each mattress's self-reported firmness label against its construction type, comfort-layer thickness, sleep-position fit, and published ILD (Indentation Load Deflection) where a brand actually discloses it. Most rows show 'Not disclosed' for ILD — that gap is itself the finding, not a data-entry omission.
Because most mattress brands market with a subjective 1-10 number or a Soft/Medium/Firm word instead of the objective ILD figure. Only a minority of brands in this dataset (Brooklyn Bedding, across three products) publish per-layer ILD on their spec sheets.
Use it to compare like-for-like: construction type first, then ILD only within the same construction type where disclosed, then self-reported label as the least reliable signal since it isn't standardized across brands. Cross-brand self-reported numbers are not directly comparable.
No. It reports firmness, ILD, and construction facts for equipment-fit purposes only — never a claim that any mattress treats, prevents, or relieves back pain or any other condition.