Norwood–Hamilton · Stage IV
Norwood 4 (IV)
Further frontal recession plus a larger vertex. A band of hair still separates the two zones.
No account needed, and nothing is stored.
What it looks like
Two islands of loss: a receded front and a vertex patch, with hair still crossing the mid-scalp between them. From the front the hairline is well back. From above you can still trace a strip of hair that is not the horseshoe; that strip is the bridge.
Typical measurements
Face-normalised units: H is glabella to chin, so the numbers do not depend on the phone or the distance. These are the anchors the pipeline uses; they are not a diagnosis.
- Mid-frontal height
- ≈ 0.84 H and up
- Temple bald-column share
- ≈ 60%+
- Vertex vs occipital
- ≈ 0.40 – 0.65
- Scalp loss-area
- ≈ 0.34
Norwood IV is the first stage that is almost always two-zone. The front has moved past the deep-M of III; the vertex is a patch you could circle with a finger. Between them, hair. That remaining mid-scalp band is what the engine calls the bridge. Intact bridge plus deep front plus vertex → IV. Thinning bridge → V. Bridge gone → VI.
Loss-area at this grade is about 0.34 in the 2025 dermatologist-graded set. IV and V sit close on that one number (V is about 0.40), which is why bridge density is the tie-break rather than area alone. A report that only said “about 35% scalp showing” would bounce between IV and V; the band is the thing to look at.
The anterior variant (IVa in Norwood’s later types) is a deep front without a separate crown patch: the recession marched back as a single line. The engine notes this explicitly when frontal class is 4 or more, vertex is still 0, and the bridge is not gone. It is not a III that “looks bad from the front.”
How it gets mixed up
The band is the whole difference between IV and V. On IV it is still a band of hair. On V it is a sparse remnant. If the front is deep and there is no separate crown patch, that is the anterior (“a”) variant of IV, not a mis-staged III.
How to get your number
Five photos (front, left, right, crown, back), a sixty-second history, about three minutes. The report costs $7, needs no account, and stores nothing. You get the roman stage, a continuous index, a genetic vs. environmental split, levers ranked by evidence, 5- and 10-year paths, and a signed link. Look at a sample report first. Details of the geometry and the papers behind the anchors: Method & sources. The rest of the scale: Norwood I–VII.
FAQ
Norwood 4 vs 5?
Both have front and vertex. On IV the mid-scalp band is still hair. On V it has thinned to a remnant. Loss-area only moves from about 0.34 to 0.40; the bridge measurement is what actually changes the label.
What is Norwood 4a?
The anterior variant: deep frontal recession without a separate vertex island. The hairline has moved back as a front, not as an M plus a crown. norwood.fyi labels this “IV (anterior variant)” when the crown is still intact and the front is already in the IV range.
norwood.fyi is an informational tool, not a medical device, and not a substitute for a dermatologist. Staging between adjacent Norwood grades has about 65–78% agreement even among experts; the report shows its confidence and the measurements behind it.