Glossary
Sinclair scale
A 5-point visual classification of female pattern hair loss based on the width of the central part. Sinclair 1 is normal density; Sinclair 5 is severe central thinning. Easy to apply at home with a phone selfie.
The Sinclair scale is a 5-point visual classification of female pattern hair loss developed by Rodney Sinclair. It assesses central scalp density by the width of the part, photographed from above.
The five stages:
- 1: Normal density. Part appears narrow.
- 2: Mild widening of the part.
- 3: Moderate widening; central scalp visibly thinner.
- 4: Marked thinning across the central scalp; part broadly widened.
- 5: Advanced central loss; central scalp largely bare, frontal hairline often still preserved.
The Sinclair scale is well-suited to home use. A phone selfie of the scalp from above, taken under the same lighting in the same position monthly, lets you (or your dermatologist) track stage over time.
The Ludwig scale (I, II, III) is a 3-point alternative covering similar ground. Ludwig I corresponds roughly to Sinclair 2 to 3, Ludwig II to Sinclair 3 to 4, and Ludwig III to Sinclair 5.