mattress-spec-decoder

Use when shopping for a mattress or decoding one you already own — translates marketing specs into materials science (foam density lb/ft³, ILD, coil type/count/gauge), computes your firmness band from sleep position + BMI, scores durability and real lifespan, decodes warranty sag-thresholds and prorated traps, and compares two mattresses side by side for YOUR body instead of brand marketing.

Mattress shopping is engineered confusion: every retailer gets a different model name for the same bed (so you can't price-compare), and the spec sheet is written in marketing ("UltraCool Gel Infinity Foam!") instead of the four numbers that actually predict performance: foam density, ILD, coil type/count, and layer stack order.

This skill decodes the specs, computes the firmness band your body actually needs, and tells you how many years the mattress will really last.

When to Use

• Shopping for a new mattress (online or store) and comparing options
• Decoding a spec sheet: "is 1.5 lb/ft³ foam good or garbage?"
• Choosing firmness for your sleep position and body weight
• Deciding between memory foam / latex / hybrid / innerspring
• Checking whether a warranty is real coverage or theater
• Diagnosing sagging: "is this covered or is this normal softening?"
• Two sleepers with different positions/weights: what works for both

Don't use for: medical sleep disorders (apnea — see a doctor), or crib/toddler mattresses (different safety rules: firm, tight fit, waterproof).

Core Numbers That Matter

Spec	Junk	Good	Excellent	Why
Memory foam density	<3.0 lb/ft³	3.0–4.0	>4.0	Density = lifespan. Low-density foam impressions in 1–2 years
Base (poly) foam	<1.5 lb/ft³	1.5–1.8	>1.8	The support layer nobody advertises — where cheap beds cheat
Latex density	—	4.3–5.3	5.9+	Durable across the board; weight is the tradeoff
Coil count (queen)	<300	480–900	>900 is marketing	Returns diminish past ~900; type matters more
Coil gauge	15+ (soft)	13.5–14.5	zoned 12.5–15	Lower gauge = firmer steel
ILD/IFD	—	10–15 soft / 15–25 med / 25+ firm	—	Very rarely published; ask or infer

Quick Start

bash

# Firmness band for a 78 kg / 175 cm side sleeper
python3 scripts/mattress_advisor.py recommend --position side --weight 78 --height 175

# Couple with different profiles — get the compromise band
python3 scripts/mattress_advisor.py couple --p1 side,62,168 --p2 stomach,95,182

# Decode a spec sheet
python3 scripts/mattress_advisor.py decode --type hybrid \
    --memory-density 3.0 --base-density 1.5 --coils 480 --coil-type pocketed

# Compare two mattresses for your profile
python3 scripts/mattress_advisor.py compare --profile side,78,175 \
    --a 'name="DreamCloud-ish",type=hybrid,memory_density=4.0,base_density=1.8,coils=850,coil_type=pocketed,price=1100' \
    --b 'name="Box-o-Foam",type=foam,memory_density=2.5,base_density=1.3,coils=0,price=500'

# Is the 10-year warranty worth anything?
python3 scripts/mattress_advisor.py warranty --years 10 --prorated --sag-threshold 1.5

# Sagging after 2 years — covered?
python3 scripts/mattress_advisor.py sag --measured 1.75 --threshold 1.5 --years-owned 2

Stdlib-only Python 3. Offline. No brand affiliations.

Workflow

1. Profile first. recommend → your firmness band (1–10), target ILD, mattress-type candidates, and body-specific warnings (BMI ≥ 30 needs ≥1.8 lb/ft³ base foam or impressions form fast).
2. Decode the spec sheet. decode → durability verdict per layer + expected lifespan + which specs are marketing noise.
3. Compare finalists. compare → weighted score for YOUR profile (support-fit, durability, motion isolation, heat, edge) with the reasoning printed per criterion.
4. Stress-test the warranty. warranty → sag threshold, prorated schedule math, what voids coverage. sag → verdict for your measured dip.
5. Shop outside the label. Use references/buying-playbook.md: same-bed fingerprinting, floor-model math, delivery-day inspection.

Firmness Logic (what the script computes)

Base firmness by position: side 4/10 (shoulder/hip pressure), back 6/10, stomach 7.5/10 (hip sink → spinal extension), combo 6/10. BMI shift: <19 → −1; 25–29.9 → +1; ≥30 → +2 and a hard requirement for high-density support. Couples: take the max firmness of the two profiles and solve pressure relief with a comfort layer (topper), not a softer core — split-core or dual-firmness options if the gap > 1.5 points.

Common Pitfalls

1. Trusting "10-year warranty." Most are prorated after year 1–5, require sag > 1.5" measured with a string and no load, and are voided by stains. warranty decodes this.
2. Buying by brand name. Model names are retailer-exclusive on purpose. Match specs (densities, coil count, layer stack) instead.
3. Ignoring base foam density. Everyone checks memory foam; cheap beds cheapen the SUPPORT layer below it. That's what sags.
4. One mattress, two bodies. Averages don't work: the heavier sleeper's correct firmness destroys the lighter one's spine. Solve in layers.
5. Judging in 5 minutes in a store. Memory foam needs 10+ minutes to imprint; take your time, or rely on a ≥100-night trial.
6. Confusing thick = durable. 14" of low-density foam is worse than 10" of high-density. Total height is a marketing number.
7. Firmness ≠ support. Support = spinal alignment; firmness = surface feel. Heavy people can sleep on soft IF the support layer is dense.

Verification Checklist

• recommend run with real weight/height/position
• Spec sheet decoded with actual densities (call the manufacturer — they must tell you; refusal is a verdict in itself)
• compare shows reasoning per criterion, not just a score
• Warranty decoded before purchase
• Trial period ≥ 100 nights confirmed (30-night minimum to adjust)

References

• references/mattress-science.md — density/ILD/coil deep dive, layer stack order effects, heat and off-gassing physics, lifespan tables
• references/buying-playbook.md — same-bed fingerprinting, negotiation, delivery inspection, topper-first rescue for an existing mattress