Your FUE graft yield is the total number of follicular units you can safely extract from your donor area across all transplant sessions in your lifetime. Calculating this number before surgery prevents over-harvesting and ensures you have enough supply to cover current and future hair loss.
The Graft Yield Formula
Lifetime Graft Yield = Donor Density (FU/cm2) x Safe Donor Area (cm2) x 0.45
The 0.45 factor is the safe extraction limit. Taking more than 45% of donor follicles creates visible thinning in the back and sides of the scalp.
Step 1: Determine Your Donor Density
Donor density is measured in follicular units per square centimeter (FU/cm2). A trichoscope or densitometer at your surgeon's office provides the exact number. If you do not have a measurement yet, use these averages based on ethnicity:
| Ethnicity | Avg Density (FU/cm2) | Range (FU/cm2) |
|---|---|---|
| Caucasian | 200 | 170-230 |
| Asian | 170 | 140-200 |
| African | 150 | 120-180 |
| Hispanic | 170 | 145-195 |
| Middle Eastern | 180 | 150-210 |
Note: African hair typically has fewer follicular units per cm2 but more curl, which provides better visual coverage per graft. Asian hair is thicker per strand (60-80 microns vs 50-70 for Caucasian), also providing more coverage per graft.
Step 2: Measure Your Safe Donor Area
The safe donor zone is the permanent horseshoe-shaped area on the back and sides of the scalp that is resistant to DHT (the hormone causing pattern baldness). This zone typically measures:
- Width: Ear to ear across the back of the head (approximately 25-30 cm)
- Height: From the occipital ridge down to just above the nape (approximately 6-8 cm)
- Total area: 150-200 cm2 for most patients
Your surgeon should map this zone before surgery. Do not let a clinic extract from outside the safe zone, as those follicles are not DHT-resistant and may fall out after transplantation.
Step 3: Calculate Your Yield
Here are example calculations for different profiles:
| Profile | Density | Area | Total FUs | Safe Yield (45%) |
|---|---|---|---|---|
| Caucasian, large donor | 210 FU/cm2 | 200 cm2 | 42,000 | 18,900 |
| Caucasian, average | 190 FU/cm2 | 180 cm2 | 34,200 | 15,390 |
| Asian, average | 170 FU/cm2 | 175 cm2 | 29,750 | 13,388 |
| African, average | 150 FU/cm2 | 170 cm2 | 25,500 | 11,475 |
| Low density, any | 120 FU/cm2 | 160 cm2 | 19,200 | 8,640 |
Step 4: Compare Yield Against Your Needs
Once you know your yield, compare it to the graft requirements for your current and projected Norwood stage. Use the Norwood scale graft requirements as your reference:
| Norwood Stage | Grafts Needed | Coverage |
|---|---|---|
| Norwood 2 | 800-1,500 | Slight temple recession |
| Norwood 3 | 1,500-2,200 | Deep temple recession |
| Norwood 3V | 2,000-2,800 | Temples + vertex thinning |
| Norwood 4 | 2,500-3,500 | Advanced recession + vertex |
| Norwood 5 | 3,000-4,500 | Front and vertex merging |
| Norwood 6 | 4,000-6,000 | Horseshoe pattern |
| Norwood 7 | 5,500-7,500 | Most extensive loss |
Key calculation: If your safe yield is 15,000 grafts and you are currently Norwood 3 (needing 2,000 grafts now) but may progress to Norwood 6 (needing 6,000 total), you have enough supply: 2,000 + 4,000 additional = 6,000, well within your 15,000 budget.
If your projected total need exceeds your yield, discuss supplementary options with your surgeon: body hair transplant (beard, chest), FUT to maximize per-session yield, or medical therapy (finasteride, minoxidil) to slow progression and reduce future graft requirements.
What Affects Your Real-World Yield
The formula gives a theoretical maximum. Actual yield is affected by:
- Graft survival rate: FUE achieves 90-95% survival with experienced surgeons. Budget for a 5-10% loss.
- Transection rate: Less experienced surgeons damage more grafts during extraction, reducing effective yield.
- Hair characteristics: Coarse, curly, or gray hair is harder to extract cleanly, which may increase transection.
- Previous procedures: Subtract all previously extracted grafts from your lifetime budget.
Get Your Norwood Stage First
The most important input to your graft budget is knowing how many grafts you actually need. Over 60% of men misidentify their own hair loss stage. Get an objective measurement with AI-powered Norwood staging at myhairline.ai/analyze before running your yield calculation.
FAQ
How do you calculate FUE graft yield from donor density?
Multiply your donor density (follicular units per cm2) by the safe donor area (typically 150-200 cm2), then multiply by the safe extraction rate of 45%. For example, a patient with 180 FU/cm2 across 180 cm2 has 32,400 total FUs and can safely extract 14,580 grafts across all lifetime sessions.
How does AI improve hair loss diagnosis for surgical planning?
AI tools like myhairline.ai analyze scalp photos to provide objective Norwood staging, which directly determines how many grafts you need. Knowing your exact stage (and the corresponding graft range) lets you compare that number against your donor yield to confirm you have enough supply.
What donor density is too low for FUE?
Donor density below 100 FU/cm2 generally makes FUE risky because extraction will create visible thinning quickly. Ideal FUE candidates have at least 150 FU/cm2 in the safe donor zone. Patients with low donor density may be better candidates for FUT, which removes a strip but leaves surrounding density intact.
Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. Consult a board-certified dermatologist or hair restoration surgeon before making any treatment decisions.