How is a hair transplant planned?

Which measurements decide the plan?

The plan comes from five measurements, not from what the patient asks for. They are taken at examination with a dermatoscope and a square-centimetre calculation.

• Donor density — follicular units per square centimetre at the nape and temples. This sets the total graft budget.
• Thinning area — the square centimetres to be covered. Multiplied by the target density, it gives the grafts required.
• Hair calibre — thickness in microns. Thicker hair covers the same area with fewer grafts.
• Hair-to-skin contrast — the lower the contrast, the fuller the same graft count looks.
• State of the shedding — where loss is active and fast, the plan is built for five years from now, not for today.

How is donor density measured and what does it mean?

Donor density is measured by counting follicular units per square centimetre at the nape and temples with a dermatoscope. The typical value is 60–80 units per square centimetre.

A follicular unit contains 1–4 hairs, so graft count and hair count are not the same thing. An average of 2.2 hairs per unit is assumed.

The total that can safely be taken from the donor area over a lifetime is limited; the area cannot be emptied, or permanent thinning appears in the donor itself. The first operation is therefore the first withdrawal from a budget that is never replenished.

Why does the square centimetre figure matter so much?

The grafts needed are the square centimetres of the thinning area multiplied by the target density. Any figure given without that measurement is an estimate of that multiplication.

The density targeted in a transplant is 35–45 follicular units per square centimetre at the front. On a natural scalp the figure is 80–100 units — so a transplant creates the impression of fullness with roughly half of natural density.

A worked example: a 60 cm² frontal zone at a target of 40 units per square centimetre needs about 2,400 grafts. The same area at the crown, planned with a whorl pattern, gives a different number.

How do hair calibre and contrast change the result?

Hair calibre ranges roughly between 50 and 90 microns. An 80-micron hair provides markedly more coverage over the same area than a 55-micron one.

Contrast between hair and skin is the second factor. Dark hair on fair skin gives the highest contrast; in that picture the scalp shows more easily and more grafts are needed for the same fullness.

In low-contrast pictures — light brown hair on fair skin, common across northern Europe — the same graft count looks denser. That means the target density in the plan can be brought down.

How does the plan change if the shedding is still active?

Where loss is active and fast, transplanting alone produces an unbalanced picture within a few years as the untransplanted areas open up. The transplanted zone stays; everything around it recedes.

In that picture the first aim is to slow the shedding medically; the transplant is planned once the situation is more predictable. That is not a delay but a decision to protect the donor budget.

If the shedding is continuing, the hairline is also placed further back and the temple corners are kept age-appropriately recessed. A low hairline created today can leave a band behind it in ten years that cannot be closed.

One session or two?

The number of sessions is set by the ratio between the thinning area and donor capacity. A single session typically transfers 2,000–4,500 grafts; where more is needed, the plan splits into two.

In a two-session plan the priority is the frontal zone and hairline. The crown is assessed at the second session; that order completes the area that frames the face first.

A second session is usually planned no earlier than 10–12 months after the first. That interval lets the result of the first become readable and lets the donor area recover.

What does the written plan contain?

The written plan is given to you before the operation and puts what was discussed on the record. Ask for it before you pay anything; a clinic unwilling to write the numbers down is telling you something.

• Graft distribution by area — separate numbers for hairline, frontal zone, mid-scalp and crown
• Target density — follicular units per square centimetre
• The technique chosen and the reason for it
• The position of the hairline and the planned recession of the temple corners
• The estimated timing of a second session, where one is anticipated