To understand how hair restoration works, it helps to first get familiar with the “real estate” we’re working with—your scalp and its hair-growing capacity.
How Big Is the Average Scalp?
The average scalp covers around 694 square centimeters—a little larger in men (~727 cm²) and slightly smaller in women (~658 cm²). Of this surface area, about 200 cm² makes up the regions most affected by hair loss:
- 100 cm² in the front (hairline and frontal scalp)
- 100 cm² in the back (crown and vertex)
These are the most common areas where thinning and balding occur.
How Many Hairs Are on the Scalp?
The average person has roughly 100,000 hairs on their scalp. These hairs grow in small natural groupings called follicular units, which typically contain 1 to 4 hairs, but on average, about 2 hairs per unit.
That gives you around 50,000 follicular units total. Here’s how they’re typically distributed:
- 75% (37,500 units) are in areas prone to hair loss
- 25% (12,500 units) are in the “safe donor zone”—the back and sides of the scalp
Why the Donor Area Matters
Hair used in a transplant comes from the donor area, where hair is genetically resistant to thinning. But there’s a limit to how much hair we can take without thinning the donor site.
- Only 50% of the donor zone can be safely harvested over a lifetime
- And only about 15–20% of grafts are removed during any single surgery to preserve natural density and avoid scarring
That means the average lifetime graft limit for most patients is around:
- 6,250 follicular units, or 12,500 hairs
- This is an average, meaning some people will have more or less than the average
What This Means for You
If you’ve lost most or all of your hair, it’s important to know: we can’t replace 100% of what was lost.
Even with multiple surgeries, we can typically restore only 12–13% of your original hair count. That may sound low—but here’s where the artistry of your surgeon matters most.
Using advanced design techniques, strategic placement, and natural distribution patterns, we can create the illusion of fullness with fewer hairs. It’s not about replacing every strand—it’s about strategically using what you have to get
the best visual impact.
Your scalp and donor supply set the foundation for what’s possible in hair restoration. Knowing the numbers helps set realistic expectations and guides a personalized plan that delivers natural-looking, long-term results.
