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On average, how many hairs does one lose a day? I have heard 80-100 but that figure seems a bit much to me. I was just wanting to know because that is very odd.
Both 80 and 100 are even numbers.
Seriously, though, 100 hairs a day is about 1/10 of 1% of the average head. It would take nearly 3 years at 100 hairs a day before each hair was lost or about 3 1/2 years at 80, assuming an average count of 100,000 hairs. I think the average life expectancy of a hair is generally accepted to be about 5 years, so if the 100 hairs a day number is right, the average number of hairs on a head must be closer to 180,000.
On the other hand, as with most of the other hair statistics you see here, not all hairs are the same. Some have a faster cycle. Some have a longer cycle.
Here's an interesting experiment to do that you could do to check whether this math works. If your hair is all terminal length (no cut ends), collect all hairs lost in a day. Average the length of all these hairs. Let's say they average 2 feet long. Let's also say your hair grows at 1/2 foot per year. We expect an average life expectancy of 4 years. Now let's say you've counted your hairs the way I described earlier and you have 100,000 hairs. Then the number of hairs you can expect to lose daily is 100,000 / 4 / 365 or 68. Compare this number to the number you collected.
This sort of experiment should tell you whether the number is reasonable. Of course, I've left something out, namely, that the hair undergoes a rest period. I'll leave it to the readers to work out how this would affect the formula, if at all.
Excellent calculating Victor. This is the same value I get. 100000 strands growing 6 inches per year is 50000 total feet per year. 50000 / 365 = 137 feet per day. That is 68 2 foot strands or 137 1 foot hair fragments. (Just count 2 1 foot fragments or 3 8 inch fragments as a single strand lost.) Absalom