The Norwood Scale measures male pattern baldness; the Ludwig Scale measures female pattern hair loss. These two classification systems track fundamentally different loss patterns, and using the wrong one leads to misdiagnosis and poor treatment planning. Here is everything you need to know about both scales and when each applies.
Norwood Scale Overview
The Norwood Scale (Hamilton-Norwood Scale) was developed in 1975 by Dr. O'Tar Norwood to classify androgenetic alopecia in men. It tracks hair loss across 7 stages, primarily focusing on frontal recession and vertex (crown) thinning.
Male pattern baldness follows a predictable path driven by dihydrotestosterone (DHT) sensitivity. Hair loss begins at the temples, creates an M-shaped recession, then expands toward the crown. Eventually the two areas merge, leaving only a horseshoe-shaped band of DHT-resistant hair.
Norwood Stages and Graft Requirements
| Stage | Pattern | Grafts Needed |
|---|---|---|
| Norwood 1 | No significant loss | 0 |
| Norwood 2 | Slight temple recession | 800-1,500 |
| Norwood 3 | Deep temple recession | 1,500-2,200 |
| Norwood 3V | Temple + early crown loss | 2,000-2,800 |
| Norwood 4 | Significant frontal and crown loss | 2,500-3,500 |
| Norwood 5 | Frontal and crown nearly merged | 3,000-4,500 |
| Norwood 6 | Bridge between areas lost | 4,000-6,000 |
| Norwood 7 | Only horseshoe band remains | 5,500-7,500 |
The Norwood Scale also includes a "Class A" variant where recession progresses front-to-back without a distinct vertex bald spot. This variant is less common but requires different surgical planning because the loss area is more elongated.
For a full breakdown of each stage, see the complete Norwood scale guide.
Ludwig Scale Overview
Dr. Erich Ludwig introduced this scale in 1977 to classify female pattern hair loss (FPHL). Unlike male pattern baldness, female hair loss typically presents as diffuse thinning along the central part while the frontal hairline remains intact.
Women lose hair differently because of hormonal differences. Estrogen and progesterone provide some protection against DHT, but when levels drop (menopause, hormonal conditions, or genetics), thinning spreads outward from the midline.
Ludwig Stages Explained
| Stage | Pattern | Severity |
|---|---|---|
| Ludwig I | Mild thinning along central part | Noticeable widening of the part line. Hair density reduced by roughly 20-30%. Often dismissed as normal variation. |
| Ludwig II | Moderate diffuse thinning | Part line clearly wider. Scalp visible through hair across the top. Density reduced by approximately 40-60%. Most women seek treatment at this stage. |
| Ludwig III | Extensive thinning on crown | Near-complete loss of hair density across the top of the scalp. Frontal hairline may still be preserved. Density reduced by 70% or more. |
The Savin Scale Addition
The Savin Scale expands on Ludwig by adding 8 density-based sub-stages plus a distinct frontal thinning variant. Many trichologists prefer the Savin Scale because it captures the gradual density changes that Ludwig's three broad stages miss.
Side-by-Side Comparison
| Feature | Norwood Scale | Ludwig Scale |
|---|---|---|
| Used for | Male pattern baldness | Female pattern hair loss |
| Number of stages | 7 (plus variants) | 3 |
| Primary pattern | Frontal recession + vertex thinning | Diffuse central thinning |
| Hairline affected | Yes, temples recede first | Usually preserved |
| Crown involvement | Distinct bald spot | Diffuse thinning, no defined spot |
| Age of typical onset | Late teens to 30s | 40s to 60s (often post-menopause) |
| Hormonal driver | DHT miniaturization | DHT + estrogen decline |
| Introduced | 1975 (O'Tar Norwood) | 1977 (Erich Ludwig) |
| Transplant candidacy | Stage 3+ typically | Stage II+ with stable donor |
Why the Distinction Matters for Treatment
Medical Therapy Differences
Finasteride (1mg daily) is the standard medical treatment for male pattern baldness and works by blocking DHT production. It halts further loss in 80-90% of men and produces regrowth in about 65%. However, finasteride is contraindicated in women of childbearing age due to teratogenic risks. Post-menopausal women may use it off-label under medical supervision.
Minoxidil works for both sexes. Men typically use 5% topical solution, while women start with 2% (though 5% is increasingly prescribed). Expect 40-60% moderate regrowth with consistent use over 4-6 months.
Spironolactone (an anti-androgen) is commonly prescribed for women with Ludwig-pattern loss but is not used in men because of feminizing side effects.
Surgical Planning Differences
Hair transplant planning differs significantly between the two patterns:
Norwood patients have clearly defined bald areas and relatively predictable donor zones. Surgeons can map recipient sites precisely, and the horseshoe-shaped donor area maintains consistent density. FUE harvests use 0.7-1.0mm punches, with a safe extraction limit of approximately 45% of donor follicles.
Ludwig patients present challenges because the thinning is diffuse rather than patterned. Existing miniaturized hairs may still occupy the recipient area, making it harder to place grafts without damaging native follicles. Additionally, female donor areas may also show some thinning, reducing the available graft supply.
| Consideration | Norwood Patient | Ludwig Patient |
|---|---|---|
| Donor area stability | High (DHT-resistant band) | Variable (may thin over time) |
| Recipient site planning | Defined bald zones | Diffuse, harder to target |
| Typical graft count | 800-7,500 depending on stage | 500-3,000 depending on stage |
| Session count | 1-3 sessions | Usually 1-2 sessions |
| PRP as adjunct | Helpful post-transplant | Often first-line treatment |
PRP and Non-Surgical Options
Platelet-Rich Plasma (PRP) therapy at $500-2,000 per session can increase density by 30-40%. It is particularly effective for Ludwig-pattern patients because it strengthens existing miniaturized hairs rather than replacing lost ones. For Norwood patients, PRP serves better as a post-transplant adjunct to improve graft survival.
When Patterns Cross Over
About 5-10% of hair loss cases do not fit neatly into one scale. Situations where the lines blur include:
Men with diffuse thinning. Some men experience Ludwig-like diffuse unpatterned alopecia (DUPA) rather than typical Norwood recession. These patients are generally poor transplant candidates because their donor area is also thinning. If you notice widespread thinning without a clear pattern, consult a trichologist before assuming a Norwood stage.
Women with frontal recession. A small percentage of women develop frontal fibrosing alopecia (FFA), which mimics early Norwood patterns. The Ludwig Scale does not capture this, so doctors may describe it separately. FFA is an inflammatory condition requiring different treatment than androgenetic alopecia.
Transgender patients on HRT. Hormone replacement therapy changes the hair loss pattern. Trans women on estrogen may see a shift from Norwood to Ludwig-type thinning. Trans men on testosterone may develop Norwood-pattern recession. Treatment planning must account for ongoing hormonal changes.
How to Determine Which Scale Applies to You
Follow this decision process:
- Identify your biological sex and hormone status. If male, start with Norwood. If female, start with Ludwig. If on HRT, consider both.
- Check your hairline. If your temples are receding and forming an M-shape, Norwood applies. If your hairline is intact but you see widening at the part, Ludwig applies.
- Examine the crown. A distinct bald spot at the vertex points to Norwood. Generalized thinning visible through the hair points to Ludwig.
- Assess the donor area. Pull hair aside at the back and sides. If density feels consistent and thick, the donor is stable (typical for Norwood). If you notice thinning there too, it may indicate DUPA or advanced Ludwig.
For a quick classification based on photos, use the AI analysis tool at myhairline.ai/analyze. The tool identifies Norwood stages from uploaded images and provides personalized graft estimates.
Ethnic Considerations for Both Scales
Hair density varies by ethnicity, which affects staging accuracy and treatment planning under both scales:
| Ethnicity | Avg Follicular Units per cm2 | Impact on Staging |
|---|---|---|
| Caucasian | 170-230 | Higher density can mask early stages |
| African | 120-180 | Lower FU density but higher hairs/FU and curl provides visual coverage |
| Asian | 140-200 | Straight hair shows thinning earlier |
| Hispanic | 145-195 | Moderate density, variable patterns |
| Middle Eastern | 150-210 | Good donor density for transplants |
Surgeons estimate an average of 2.2 hairs per graft across all ethnicities. Patients with higher follicular unit density may appear to be at an earlier stage than the actual follicle miniaturization would suggest.
Bottom Line
The Norwood Scale and Ludwig Scale are not competing systems. They measure different conditions in different populations. Men experiencing frontal recession and vertex thinning should reference Norwood. Women experiencing central part widening and diffuse thinning should reference Ludwig. Accurate staging is the foundation for every treatment decision that follows.
Use the graft calculator by zone to estimate your specific needs once you know your stage. Or upload a photo at myhairline.ai/analyze for an AI-powered classification in seconds.