Your donor area at Norwood 5 needs to supply 3,000 to 4,500 grafts while retaining enough density to look natural afterward. The safe extraction limit is 45% of the donor area, and the minimum viable donor density for surgery at this stage is 60 follicular units per cm2.
Understanding the Donor Area at Norwood 5
The donor area is the horseshoe-shaped band of hair running from above the ears around the back of the head. These follicles are genetically resistant to DHT and retain this resistance when transplanted to the recipient area. At Norwood 5, this is the only reliable source of permanent grafts.
The donor area at Norwood 5 typically measures 150-250 cm2 in total surface area. The usable portion (the zone dense enough for extraction without visible thinning) is usually smaller, around 100-180 cm2.
Donor Area Anatomy
| Zone | Location | Typical Density | Extraction Priority |
|---|---|---|---|
| Occipital (central back) | Mid-posterior scalp | 65-100 FU/cm2 | Primary extraction zone |
| Parietal (sides) | Above the ears | 55-85 FU/cm2 | Secondary extraction zone |
| Temporal (lower sides) | Behind the temples | 45-70 FU/cm2 | Tertiary, used cautiously |
| Nape (lower back) | Base of the skull | 40-65 FU/cm2 | Often avoided (lower survival) |
The occipital zone is the safest and densest area for extraction. Experienced surgeons extract primarily from this zone and work outward to the parietal and temporal areas as needed.
How to Assess Your Own Donor Area
Step 1: Visual Inspection
Stand in front of a well-lit mirror and use a hand mirror to examine the back and sides of your head. Look for:
- Even density: The donor fringe should appear uniformly thick without visible gaps or thin patches
- Fringe width: Measure the vertical height of the hair-bearing band above the ears. At Norwood 5, a width of 8-12 cm on each side is typical. Less than 6 cm may indicate limited supply
- Scalp visibility: If the scalp is easily visible through the donor hair under normal lighting, density may be below the threshold for surgery
Step 2: The Pull Test
Gently grasp a small cluster (about 40-60 hairs) of donor hair between your thumb and forefinger. Pull slowly with steady pressure. If more than 6-8 hairs come out, this may indicate telogen effluvium or diffuse thinning in the donor area, which warrants further investigation.
Step 3: Trichoscopy (Clinical Assessment)
A trichoscopy exam uses a magnifying dermatoscope (60-70x magnification) to evaluate the donor area at the follicular level. This is the gold standard for donor assessment and should be performed during any surgical consultation.
What trichoscopy reveals:
- Follicular unit density: Precise count of FU/cm2 across multiple sample points
- Hairs per follicular unit: The average (2.2 overall) varies by zone. Higher averages mean more coverage per graft
- Miniaturization percentage: The ratio of thin, vellus-like hairs to thick, terminal hairs. A miniaturization rate above 20% in the donor area is a concern
- Hair shaft diameter: Coarser hair (60-80 microns) provides significantly more coverage than fine hair (40-50 microns)
Step 4: Calculate Your Graft Supply
Once you know your donor density and usable area, the calculation is straightforward:
Available grafts = Usable donor area (cm2) x Density (FU/cm2) x 0.45 (safe extraction limit)
Example for a typical Norwood 5 patient:
- Usable donor area: 140 cm2
- Average density: 75 FU/cm2
- Total follicular units: 140 x 75 = 10,500
- Safe extraction (45%): 10,500 x 0.45 = 4,725 grafts available
This patient could comfortably supply 4,500 grafts across one or two sessions while staying within the 45% safe limit.
The 45% Safe Extraction Limit Explained
Extracting 45% of the donor follicular units leaves the donor area looking naturally full. The remaining 55% of follicles provide enough density (typically 35-55 FU/cm2 post-extraction) that the donor zone does not appear depleted.
Exceeding this limit carries real consequences:
- Visible donor thinning: The back and sides of the head look noticeably thinner, which is cosmetically unacceptable
- Moth-eaten appearance: In FUE, over-extraction creates irregular sparse patches rather than uniform thinning
- No reserve for future procedures: If hair loss progresses to Norwood 6 or 7, there are no remaining grafts available for touch-ups
FUE vs. FUT Extraction Considerations
| Factor | FUE | FUT |
|---|---|---|
| Extraction method | Individual punch (0.7-1.0mm) | Strip excision, grafts dissected |
| Max grafts per session | Up to 5,000 | Up to 4,000 |
| Donor scarring | Tiny dot scars (nearly invisible at 2mm+ hair length) | Linear scar (concealed at medium+ length) |
| Impact on future extraction | Reduces available FU for future FUE sessions | Donor area can still be used for FUE later |
| Donor density post-procedure | Uniform mild reduction | Localized reduction at strip site |
A strategic consideration at Norwood 5: Some surgeons recommend FUT for the first session (maximizing graft yield from the strip) and FUE for a potential second session. This approach accesses the donor area via two different mechanisms and can maximize total lifetime graft availability.
Red Flags: When the Donor Area Is Compromised
Diffuse Unpatterned Alopecia (DUPA)
DUPA causes thinning throughout the scalp, including the donor area. Unlike standard androgenetic alopecia, DUPA does not follow the classic horseshoe pattern. If your donor area shows significant miniaturization (above 20% on trichoscopy), transplanted grafts may not be permanent.
Retrograde Alopecia
This condition causes the donor fringe to thin from the bottom up (the nape area thins first, then the occipital). It narrows the usable donor zone and reduces the total available graft supply. Retrograde alopecia is more common in men over 60.
Previous Surgery or Scarring
If you have had a previous FUT procedure, the linear scar reduces the extractable area. Previous FUE sessions reduce follicular unit density in the extraction zones. Any prior surgical history must be disclosed so the surgeon can accurately calculate remaining supply.
Body Hair as a Supplemental Donor Source
When the scalp donor area is insufficient, some surgeons extract grafts from the beard, chest, or back. Body hair transplant (BHT) is not a replacement for scalp donor hair, but it can supplement it:
- Beard hair: Most similar to scalp hair in caliber. Can provide 1,000-2,000 additional grafts
- Chest hair: Finer and grows in a shorter cycle. Used primarily for adding density to the crown
- Survival rates: Body hair grafts have lower survival rates (70-80%) compared to scalp grafts (90-95%)
BHT is considered a secondary option and is not available at all clinics. It requires a surgeon with specific training in body hair extraction.
Get Your Donor Assessment
For a preliminary analysis of your donor area viability and estimated graft availability, upload photos of the back and sides of your head at myhairline.ai/analyze. The AI assessment evaluates visible donor density and provides an initial estimate of your surgical options.