How we capture 32 distinct attributes across 5 scalp zones — and turn them into an objective, data-driven hair assessment.
Schema v1.0 · ratemyhair.ai · Internal reference specification
Simulated output for a Norwood III specimen. All values are mock data for demonstration purposes.
Gates on visibility. Captures recession depth, diffusion, miniaturization, and asymmetry — the most critical signals for Norwood staging.
Vertex assessment including pattern type (circular vs diffuse), whorl exposure, and miniaturization — maps to Norwood vertex subtypes.
The bridge between hairline and crown. Bridge loss is the single most important signal for advanced Norwood staging (V+).
Temporal thinning is a clinical red flag — androgenetic alopecia typically spares these areas. High scores trigger alternative diagnosis flags.
Highest-priority health screening zone. Follicular loss can indicate scarring alopecia — a serious condition requiring professional evaluation.
The Norwood class is derived post-annotation from three key zone attributes: temple recession (Zone A), crown thinning (Zone B), and bridge loss (Zone C).
| Stage | Derivation Rule |
|---|---|
| I – II | Temple recession ≤ 2, crown thinning ≤ 1 |
| IIa | Temple recession = 2, frontal thinning ≥ 3 |
| III | Temple recession ≥ 3, crown ≤ 2, bridge intact |
| III Vertex | Temple recession ≥ 3, crown ≥ 3, bridge intact |
| IV | Temple recession ≥ 3, crown ≥ 3, bridge ≤ 3 |
| V | Temple recession ≥ 4, crown ≥ 4, bridge ≥ 4 |
| VI | Bridge lost, crown ≥ 4 |
| VII | Bridge lost, crown = 5, frontal = 5 |
Non-androgenetic patterns — such as diffuse thinning without recession or patchy loss — are classified as "unclassifiable" on the Norwood scale. The schema includes temporal miniaturization and follicular loss as clinical red flags that trigger dermatologist referral recommendations.
Every image is scored across 8 metadata dimensions that directly affect assessment confidence. Wet hair, poor focus, and heavy styling all reduce certainty.
Good · Moderate · Poor
Top-down · Front · Side · Rear
Sharp · Moderate · Blurry
Dry · Wet · Damp
Close-up · Head · Upper Body
Unstyled · Light · Heavy
Full Top · Crown · Sides
1–5 composite score