When estimating the number of grafts a person needs, I always want to know the hair thickness of the person. The lower graphic I initially saw on Reddit clearly defined the reasons for this. For a visual representation, the graphic artist kept the number of hairs the same (density) and changed the thickness of the hair to show the difference in coverage. Dr. Sharon Keene nicely discussed this with actual hairs that mirror. So you see, if your hair is fine, it will take a lot more hair to get the fullness of a person with medium-weight or coarse hair. This is why people with fine hair often get a second hair transplant. The fullness seen may not be as good as if the hair shafts were thicker, and even with a second hair transplant, they might not get the bulk they want. Therefore, two fine-thickness hair transplants with the same number of hairs may or may not equal one medium-thickness hair transplant, depending on how much hair bulk is in each hair shaft. It is also true that two medium-thickness hair transplants with the same number of hairs may or may not equal one coarse hair transplant, depending on how much hair bulk is in each hair shaft. The chart below shows this well. If you look at the chart below, you will see that a man with medium hair (40 microns thick) has 5.7 times the hair bulk as a person with fine hair (30 microns) per hair shaft. The amount of hair bulk is a simple math question reflecting the area of a circle is [ Pie (r)² ]. If you want to run the calculations, you will know the value of your hair thickness, and everyone having a hair transplant should do this to establish realistic expectations. For those readers who want to know where they stand, you can purchase a micrometer for under $25 on Amazon: https://www.amazon.com/dp/B09964YBMF?ref=ppx_yo2ov_dt_b_product_details&th=1
In the late 1980’s. Dr. Manny Marritt had a human volunteer with a medium weight (45 micron hair thickness), black hair agree to have half of the hairs on one side of his head plucked out. Then he brought in independent observers and photographers to see if the lower density side could be detected. The answer was NO!
The illustrations below show the same number of hairs, but the hairs are thicker. Please note the HUGE visual difference between fine, medium, and coarse hairs.
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