AI classifies your Norwood stage by analyzing hairline shape, temple recession depth, and crown density from uploaded photos. Modern models match dermatologist assessments 85-92% of the time when given clear images, making AI a practical first-step screening tool before you commit to a clinical consultation.
How the Classification Works
Image Analysis Pipeline
When you upload a photo to an AI hair loss tool, the system follows a structured process:
- Face and scalp detection. The model identifies the boundaries of the hairline, forehead, and scalp.
- Landmark mapping. Key points are plotted along the hairline, including the central hairline, temporal points, and vertex region.
- Recession measurement. The AI calculates the distance between the detected hairline and expected baseline positions, estimating the degree of temporal and frontal recession.
- Density estimation. For top-down photos, the model estimates hair density across zones by analyzing the ratio of scalp-visible pixels to hair-covered pixels.
- Stage classification. The measurements are compared against trained patterns for each Norwood stage, and the model outputs a classification with a confidence score.
What the AI Measures
| Feature | How It Is Detected | Relevance |
|---|---|---|
| Temple recession depth | Distance from temporal point to central hairline | Primary Norwood differentiator |
| Hairline shape | Contour analysis (straight, M-shaped, U-shaped) | Distinguishes stages 2-4 |
| Crown density | Pixel ratio analysis of vertex area | Identifies 3V and stages 4-7 |
| Bridge presence | Connection between frontal and crown hair | Separates stages 5 and 6 |
| Overall density pattern | Density gradient mapping across scalp | Detects diffuse thinning |
Accuracy by Stage
AI classification accuracy is not uniform across all Norwood stages. Some stages are easier to distinguish than others.
| Stage | AI Accuracy | Why |
|---|---|---|
| Norwood 1 | 90-95% | Full hairline is easy to identify |
| Norwood 2 | 75-85% | Subtle recession is hardest to distinguish from a mature hairline |
| Norwood 3 | 85-90% | Clear M-shape is a reliable visual marker |
| Norwood 3V | 80-88% | Requires crown assessment, which depends on photo angle |
| Norwood 4 | 85-92% | Distinct frontal and crown loss zones |
| Norwood 5 | 88-93% | Narrowing bridge is a strong visual signal |
| Norwood 6 | 90-95% | Merged loss area is highly recognizable |
| Norwood 7 | 92-97% | Horseshoe pattern is unmistakable |
The weakest accuracy falls between Norwood 2 and 3, where the boundary between a mature hairline and early pathological recession is genuinely ambiguous. Even experienced dermatologists disagree on this boundary in roughly 15-20% of cases.
AI vs. Clinical Assessment
What AI Does Well
- Provides an instant, objective stage estimate without scheduling a consultation
- Removes the emotional bias of self-assessment (most men underestimate their stage by 0.5-1 level)
- Tracks changes over time when photos are taken consistently
- Delivers graft count estimates based on established ranges per stage
What AI Cannot Do
- Measure follicular unit density (requires a densitometer at 170-230 FU/cm2 for Caucasian patients)
- Assess hair shaft caliber or miniaturization ratio
- Evaluate scalp laxity or donor area health
- Detect underlying medical conditions (thyroid, autoimmune, nutritional)
- Account for ethnic hair density variations (Caucasian 170-230 FU/cm2, African 120-180, Asian 140-200)
- Replace a surgeon's hands-on evaluation for transplant planning
Comparison Table
| Capability | AI Tool | Dermatologist | Trichologist |
|---|---|---|---|
| Norwood staging | Yes (85-92%) | Yes (95%+) | Yes (95%+) |
| Donor density measurement | No | Limited | Yes (densitometry) |
| Miniaturization ratio | No | With dermoscopy | Yes |
| Treatment recommendation | General guidance | Personalized | Personalized |
| Cost | Free to low cost | $100-300 consultation | $150-400 consultation |
| Time to result | Seconds | Days to weeks (appointment wait) | Days to weeks |
| Follow-up tracking | Automated | Manual | Manual |
How to Get the Best AI Results
Photo quality directly impacts classification accuracy. Follow these guidelines:
Lighting
Use natural daylight or soft, even artificial light. Avoid direct flash (creates glare on the scalp) and harsh overhead fluorescents (exaggerates thinning). The ideal setup is indirect light from a window.
Hair State
Photograph dry, unstyled hair. Wet hair clumps and shows more scalp. Heavily styled or product-laden hair hides recession. If you use fibers or concealers, wash them out before photographing.
Required Angles
- Frontal: Face the camera, pull hair back from the forehead, expose both temples
- Top-down: Hold the camera or phone directly above your head, looking straight down
- Right profile and left profile: Turn 90 degrees to show the depth of temporal recession
Resolution
Use at least a 5-megapixel camera (standard on any modern phone). Ensure the entire hairline is in focus. Blurry edges make it impossible for the model to accurately map landmark points.
Try It Now
Upload your photos at myhairline.ai/analyze for an instant Norwood stage classification. The tool provides your estimated stage, confidence level, and a graft count range based on the Norwood scale stages.
Use the results as a starting point. If the AI places you at Norwood 3 or higher, a clinical consultation with a hair transplant surgeon is the logical next step. For graft estimates broken down by scalp zone, check the graft calculator.