Mapping the safe donor zone before a single graft is taken

What the safe zone actually is

The safe donor zone is a horseshoe band across the back and sides of the head, typically six to eight centimetres tall, where follicles are not sensitive to DHT. Its upper border sits below the point where the skull curves inward; its lower border sits above the nape, where hair thins with age. Grafts taken above that upper border may be programmed to fall out later, which is how a result that looked good at thirty thins at fifty. Our lifetime guarantee exists because we harvest inside those lines.

The measurements we take, and why before shaving

We take three readings: follicular density per square centimetre with a densitometer, the average number of hairs per unit, and the degree of miniaturisation among existing donor hairs. Miniaturisation matters most, because a donor that looks dense but holds many thin, shortened hairs is already under hormonal pressure and will not tolerate a hard harvest. We do this before shaving, with the hair combed to its natural parting, since a clipped head hides both the whorl and the thinning.

Turning density into an available number

A donor with eighty follicular units per square centimetre across roughly 120 to 160 square centimetres of safe zone holds around ten thousand units. A harvest of a quarter to a third gives 2,500 to 3,300 in a first session and a similar reserve for later. Those figures collapse quickly with fine hair, low density or a narrow band. That is why two patients with identical hairlines receive different plans, and why a graft number quoted from one phone photograph is a guess.

The extraction pattern nobody sees but everyone judges

Punches are spread across the whole band rather than concentrated where they are easiest to reach, so no square centimetre loses more than about a quarter of its units. Concentrated harvesting is faster and leaves moth-eaten patches that appear the first time you clip your hair short, often a year later. Ask any clinic for a donor photograph at month twelve with the head clipped to a number two; that image tells you more than any hairline shot.

The Ones People Actually Ask.