Natural hairline density requires 35 to 45 follicular units per square centimeter, while the crown needs 50 to 70 FU/cm2 for full cosmetic coverage. These numbers vary by zone, by ethnicity, and by individual donor supply. myhairline.ai maps density targets before surgery and tracks whether each zone achieves its planned density during the 18-month growth period.
This content is for informational purposes only and does not constitute medical advice. Always consult a qualified medical professional for treatment decisions.
Why Density Design Matters More Than Graft Count
Most patients focus on total graft count when evaluating a surgical plan. A Norwood 4 patient might hear "3,000 grafts" and assume that number determines the outcome. In reality, where those grafts go matters more than the total.
A surgeon placing 3,000 grafts evenly across all zones produces a different result than one who concentrates density at the hairline and feathers it through the mid-scalp. Tracking density per zone, not just total grafts, reveals whether the distribution strategy produced a natural result.
Step 1: Map Your Pre-Op Density Baseline
Before surgery, use myhairline.ai to scan and record density readings in each target zone. This creates the "before" half of your comparison dataset.
Zones to map:
- Hairline (first 1 to 2 cm of frontal hair)
- Temples (left and right independently)
- Mid-scalp transition area
- Crown/vertex
- Donor area (occipital region)
Your donor density determines the supply ceiling for the entire procedure. Average donor densities by ethnicity:
| Ethnicity | Average Donor Density (FU/cm2) | Range |
|---|---|---|
| Caucasian | 200 | 170 to 230 |
| African | 150 | 120 to 180 |
| Asian | 170 | 140 to 200 |
| Hispanic | 170 | 145 to 195 |
| Middle Eastern | 180 | 150 to 210 |
The safe extraction limit is approximately 45% of the donor area. Exceeding this threshold risks visible donor depletion. Your pre-op scan quantifies how much supply is available for distribution.
Step 2: Define Zone-Specific Density Targets
Work with your surgeon to set explicit density targets for each zone before the procedure. Use these clinical benchmarks as a starting framework:
| Scalp Zone | Target Density (FU/cm2) | Priority |
|---|---|---|
| Hairline border | 35 to 45 | Highest |
| Frontal zone | 30 to 40 | High |
| Mid-scalp | 25 to 35 | Medium |
| Crown/vertex | 50 to 70 | High (if treated) |
| Temples | 25 to 35 | Medium |
Record these targets in your tracking profile. myhairline.ai uses them as reference points when generating post-op comparison reports. Without explicit targets, post-op density readings lack the context needed to evaluate success.
Step 3: Track Post-Op Density Against the Plan
After surgery, your scan schedule should produce density readings at regular intervals. Here is when to scan and what the data should show:
Month 3: Baseline post-shock-loss reading. Density may be at or below your pre-op level due to shock loss and graft dormancy. This is normal.
Month 6: Early regrowth density. Expect 40% to 60% of your target density in each zone. Zones that show less than 30% of target density at month 6 may warrant a discussion with your surgeon.
Month 9: Mid-maturation density. Target zones should show 60% to 80% of planned density. Zone-to-zone variation becomes clearer at this stage.
Month 12: Near-final density. Most zones should reach 80% to 95% of the planned target. The graft survival rate for FUE, FUT, and DHI procedures is 90% to 95%, so achieving 90% of planned density is a strong result.
Month 18: Final density assessment. Any zone still below 85% of target at this point is unlikely to improve further without intervention.
Step 4: Identify Underperforming Zones
Your density data reveals zone-specific performance. Common patterns include:
Crown underperformance: The crown is the most difficult zone to achieve full density because hair grows in a whorl pattern. Many patients need a second session focused specifically on crown density.
Temple asymmetry: Left and right temples may show different density readings. A difference greater than 15% between sides at month 12 suggests uneven graft placement or survival.
Hairline thinning: If the hairline zone shows less than 35 FU/cm2 at month 12, the result will appear sparse at close range. This zone benefits most from adjunct treatments like PRP ($500 to $2,000 per session) which can increase density by 30% to 40%.
Step 5: Use Data in Follow-Up Consultations
Bring your zone-by-zone density report to any follow-up consultation. The report should include:
- Pre-op density readings per zone
- Planned density targets per zone
- Actual density readings at months 6, 9, 12, and 18
- Percentage of target achieved in each zone
- Growth rate trend per zone
This data turns a subjective conversation into an objective assessment. Instead of "I think my crown looks thin," you present "my crown density at month 12 is 38 FU/cm2 against a target of 55 FU/cm2, which is 69% of plan."
Surgeons and dermatologists respond to quantified data. It helps them recommend precise interventions: additional grafting in specific zones, PRP therapy for borderline zones, or minoxidil (which produces 40% to 60% moderate regrowth) for overall density support.
Graft Counts by Norwood Stage
For context on how total graft count relates to your density plan:
| Norwood Stage | Typical Grafts | Zones Covered |
|---|---|---|
| N2 | 800 to 1,500 | Hairline and temples |
| N3 | 1,500 to 2,200 | Hairline, temples, frontal |
| N4 | 2,500 to 3,500 | Hairline through mid-scalp |
| N5 | 3,000 to 4,500 | Hairline through vertex |
| N6 | 4,000 to 6,000 | Full coverage |
| N7 | 5,500 to 7,500 | Full coverage, maximum density |
Your density design distributes these grafts across zones based on your individual anatomy, existing density, and cosmetic priorities.
Start Your Density Design Plan
Whether you are in the pre-op planning phase or already recovering from a procedure, density mapping gives you the data to evaluate your results objectively. Visit myhairline.ai/analyze to scan your current density and build the baseline for your hair transplant decision and recovery guide.
For patients evaluating their donor supply before committing to a procedure, see our donor density assessment guide.