Donor capacity: a limited account

A hair transplant is really a redistribution: no new hair is created; follicles from a loss-resistant zone are moved to thinning areas. The hidden protagonist of every plan is therefore the donor area. How many grafts can be taken decides where and how much can be placed.

The safe donor zone

The horseshoe-shaped band from above the ears to the nape is the area least affected by male pattern loss. Its follicles are relatively resistant to the hormonal effect behind the loss and keep that property after transplantation. Harvesting outside this band — for example from its upper edge, which may thin later — can lead to transplanted hairs thinning years down the line.

How density is measured

At examination, a magnifying device called a dermatoscope is used to count follicular units and hairs per unit in a defined area. Typical density is 60–90 FU/cm². Hair calibre, the width of the donor zone and skin elasticity are also assessed.

Why it is limited

Every unit taken from the donor area is gone for good. The amount the area can give without visible thinning is usually limited to a certain share of existing units. Beyond that, the back of the head starts to look “moth-eaten”, which is very hard to correct.

Risks of over-harvesting

• Visible donor thinning and patches noticeable with short haircuts
• No grafts left for a possible future session
• Grafts from outside the safe zone thinning over time
• Longer healing and a higher risk of lasting marks

Body and beard donors

When scalp donor supply is not enough, beard or chest hair can be considered as an additional source. These hairs differ in calibre, growth cycle and length, so they are mainly used as support in the mid-scalp or crown, not at the hairline.

Planning for a lifetime

A good plan meets today’s need while allowing for possible future loss. For younger patients, part of the donor supply is often kept in reserve. That is why the right answer is sometimes “less, for now”.

In the Folyara simulator, your chosen area and density are compared with an average donor capacity and you are warned as you approach the limit. Your real capacity can only be measured at examination.

The information on this page is general and does not replace a medical consultation. The method, graft number and timeline suitable for you can only be determined after an examination. Simulations are illustrative and are not a promise of results.