What are grafts? Hairs per graft, harvesting and growth explained

Anyone looking into a hair transplant will come across the word graft in almost every offer and consultation. It refers to the small unit that is transplanted – but what exactly lies behind it, how many hairs does a graft carry, and why does the number alone say so little about the eventual result?

Medically reviewed by Dr. med. Martin Reifenrath, Specialist in Plastic and Aesthetic Surgery · Last updated: 30 September 2026

What is a graft?

“Graft” simply means a transplant. In a hair transplant, it refers to a follicular unit: a naturally grown group of hairs that emerge from the scalp together, along with their roots and a little surrounding tissue. The international professional society for hair surgery (ISHRS) describes these groups as having one to four hairs each. Most are groups of one, two or three.

Modern procedures therefore do not transplant hair by hair, but group by group. This preserves the natural grouping of the hairs.

How many hairs does a graft have – and how many grafts does a person have?

A graft usually carries one to four hairs. 2,000 grafts are therefore not 2,000 hairs but, as a rule, considerably more. How the groups are made up is individual: in a study of 50 people published in 1999, 65 to 85 follicular units and 124 to 200 hairs per square centimetre were found in the donor area at the back of the head; the proportion of groups of one, two and three depended on hair density.

According to a review in the German medical journal Deutsches Ärzteblatt, around 80,000 to 120,000 strong hairs normally grow on the whole head – mathematically, several tens of thousands of follicular units. For a transplant, however, only the donor area at the back and sides of the head counts, as its hairs barely react to the hormonal influences that trigger hereditary hair loss.

How many grafts can be harvested from it over the years, and how many a particular zone needs, is shown in the article How many grafts do I need? The graft calculator gives you an initial guide value for your zone.

How are grafts harvested and handled?

There are two ways of harvesting. In single extraction (FUE), each follicular unit is removed individually from the fringe of hair with a fine hollow needle. In the strip technique (FUT), a narrow strip of skin is removed from the back of the head and divided into individual grafts under the microscope; the wound is stitched.

The grafts are then sorted, usually by the number of hairs: grafts with single hairs are suitable for the very front row of the hairline, larger groups for the areas behind it. Until they are placed, they are kept in a solution that is usually chilled, because outside the body they lack a supply of blood and oxygen. A 2015 review refers to studies according to which grafts survive well in such chilled solutions for just under eight hours before their survival rate falls. That is why it is important to handle them gently and not to leave them outside the body for longer than necessary.

Tiny openings are then made in the recipient area, into which the grafts are placed. Angle, direction and spacing help determine how naturally the hair will fall later.

Why is the number of grafts limited?

A hair transplant does not create new hair; it redistributes existing hair. The professional society puts it in a nutshell: donor hair, once harvested, is gone for good. Overusing the donor area or harvesting outside the safe zone risks visible thinning and patchy areas at the back of the head that cannot be reversed.

In addition, hereditary hair loss often continues to progress. Forward-looking planning therefore keeps reserves for later. One review names the shortage of donor hair as a key obstacle: with pronounced hair loss, it is often not possible to treat all thinning areas.

There is therefore no general answer to the question of how many grafts can be harvested at most. It depends on the density and size of the donor area, on the hairs themselves and on the method. Guide values for a single session can be found in the FUE and FUT comparison.

When are the grafts secure?

Immediately after the procedure, the grafts sit only loosely in their small channels. A study of 42 patients published in 2006 measured how long they remain vulnerable: in the first two days, pulling on a hair dislodged the graft every time, but no longer from the sixth day. Adherent crusts remained a risk for longer – pulling at them caused the graft underneath to be lost up to and including the fifth day. From the ninth day, the grafts were no longer at risk.

This explains the rules for the first few days: do not scratch, avoid friction, do not pull off crusts and wash as gently as your practice instructs. If in doubt, its schedule always applies. More on this in the article Aftercare after a hair transplant.

Why do the transplanted hairs fall out after a few weeks?

Many people are alarmed when the freshly transplanted hairs fall out a few weeks after the procedure. Usually this is not a loss: only the hair shaft falls out; the root stays in the skin, goes through a resting phase and then forms a new hair. Because scalp hair grows only about one centimetre a month, it often takes a year or more before the result can be assessed.

This should be distinguished from so-called shock loss, in which existing, non-transplanted hairs in the treated area fall out, typically two to six weeks after the procedure. This, too, is usually temporary, but can sometimes be permanent. What is normal in which phase is described in the article Hair transplant: the timeline.

Why does the number of grafts alone say little?

A high number of grafts sounds like a lot of hair. But other factors count for the result:

• how many hairs the grafts carry on average – this varies from person to person,
• how thick, wavy or light the hairs are and how much they contrast with the scalp,
• how gently the grafts are harvested, stored and placed,
• whether direction, angle and distribution suit the zone, especially at the hairline and parting,
• how hair loss develops around the transplanted hairs.

A number in an offer is therefore not a mark of quality in itself. It is more telling whether it is clearly explained where the grafts come from, what remains in the donor area and why a certain number makes sense for the desired zone.

Frequently asked questions

Medical note:This article is for general information only and does not replace a medical examination, diagnosis or consultation. Whether a treatment is suitable for you, and which one, should be discussed in person with a specialist. Treatment results vary from person to person.