The donor area — the back and sides of the scalp — is the engine of any hair transplant. It provides the permanent, DHT-resistant follicles that, once transplanted, will grow for life in their new location. Understanding your donor zone is essential before committing to any procedure.
Why Donor Hair Is Permanent
Hair on the back and sides of the scalp is genetically programmed to resist dihydrotestosterone (DHT), the hormone responsible for male pattern baldness. When these follicles are transplanted to balding areas, they retain this resistance and continue growing permanently — regardless of where they are placed.
What Surgeons Assess in Your Donor Zone
Density
The number of follicular units per cm². Average density is 80–100 FU/cm². Patients with higher-than-average density have more grafts available and can afford to harvest more without depleting the zone visually.
Hair Calibre
Thicker, coarser hair provides more coverage per graft. Hair calibre is partly genetic and partly influenced by overall health.
Miniaturisation
Under magnification, surgeons check for miniaturised follicles — hairs that are thinning and at risk of future loss. Transplanting from areas of miniaturisation risks poor graft survival.
Safe Donor Zone
The true permanent zone — where hair is genuinely DHT-resistant — does not extend across the entire back of the scalp. Some patients have a narrower safe zone than others, which limits total harvestable grafts.
Protecting Your Donor Area
Overharvesting — taking too many grafts in a single session or across multiple sessions — leaves the donor area visibly depleted. Reputable surgeons never harvest more than 40–50% of available grafts from the safe zone to ensure the area continues to look natural.
Supplementary Donor Sources
When scalp donor supply is limited, beard and body hair can supplement the harvest. These grafts have different characteristics and require specialist experience to use effectively.
Get a free donor area assessment to find out your graft potential →
Related reading
