You generally place the hair line where you want the hair line after you and your doctor go over the options. Many doctors go by proportions of your face using the Golden Ratio.
"I asked the same question a few years ago. To answer this question, I studied over 1000 children from 5-18 of both sexes and studied the hairlines from a physiologic and evolutionary point of view. I also extensive studied thousands of men and women's hair lines and looked at all of the recent publications on men and women's hairlines in the medical literature. I published all of this in a medical journal which is put into the web reference below. I believe that this is the only such publication ever written and I would be happy to clarify the medical writing for anyone confused by the medical jargon. Doctors too often quote artists conception like the Mona Lisa, but there are some general similarities between people which define normal once you subtract the unusual genetics that alters a hairline during a person's lifetime.
Thank you for your question. We like to use the rule of 1/3's. According to Leonardo Da Vinici the perfect face is when the face is divided to equal one-thirds. The distance between the eyebrows and the hairline should be half the distance between the chin and the eyebrows.
If the hairline is placed too low, then the focus will be on the chin looking too exaggerated, if the hairline is placed too high, then the forehead looks too large.
There are many factors that determines the perfect placement, one is the amount of donor region, age, and extent of the hairloss. If all is not a concern, the perfect placement would be at 1/3 distance to highlite the patient's mid face, which should be the eyes, nose, and cheekbones.
Hope this helped.
Generally I don't design a frontal hair line that middle portion less than 7 cm distance from glabellar area (between 2 eye brow). But actually frontal hair line should be assessed according to anatomic landmarks and forehead upper boundry mark .
The rule of 1/3 applies. The vertical distance of the face , from the hairline to between the eyebrows , should be the same as from between the eyebrows to the nasal spine, and should be same as the distance from the nasal spine to the lowest point of chin.
I find that in Asians, it's usually 6.5-7cm and for Caucasians , it's slightly more than that .
Hairline placement with transplants or hairline advancement? Da Vinci says 1/3 the length of the face. This is usually 6-7 cm. and is best and least expensively done with hairline advancement.