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RO The ceiling is set by the recipient area, not by the donor. Grafts arrive with no blood supply and must be reached by vessels growing out of the scalp around them. Sites cut close together share that supply and also injure the tissue that has to provide it. Past a certain spacing, adding grafts stops adding hair — it divides the same circulation among more of them.
There is a documented threshold, and it is lower than the marketing suggests. Implantation density above 45 follicular units per square centimetre appears in the complications literature as a risk factor for folliculitis, alongside sessions exceeding 4,000 grafts (Romera de Blas et al., Frontiers in Medicine, 2026). Densities quoted well above that figure are describing what was placed, not what survived.
| Packed tighter | What follows |
|---|---|
| Circulation | Shared among more grafts, per-graft supply falls |
| Recipient tissue | More incisions per area, more injury between them |
| Yield | Survival falls; total growing hair can drop |
| Donor | Spent faster for a smaller visible gain |
The number that matters is measured a year later. Density placed is a decision; density kept is a result. A packed area that loses a share of its grafts ends up thinner than a moderately planted one that keeps nearly all of them — and the difference cannot be recovered, because the donor was already spent and the extraction points do not return.
Related terms
For the pustules that follow dense implantation, see folliculitis after a hair transplant. For how a realistic graft number is reached, see how many grafts you need.
