Nevermind.
I think I found some things.. Here's one:
How Long Can Hair Get?
Three factors determine this:
How long the individual strands in your hair will live.
How strong the individual strands in your hair are.
How well you take care of them.
Let's first look at the first of those three items, how long individual hair strands live.
The Life Span of Hair
A human hair only has a life span of two to six years, after which time it falls out and a new hair soon sprouts in its place. This life span, with the growth rate we just discussed, translates into a "terminal length" of one to three feet (30 to 90 cm). Some people are genetically disposed to have longer-living hair than others, and they can therefore grow longer hair. And many people find, as they age, the life span or growth rate of their hair decreases, meaning their terminal length decreases. So each human being, if never cutting any hair, will eventually achieve a maximum hair length, and that length will most likely be between one and three feet (30 to 90 cm). The good news is that whatever length you achieve within that range, you will nevertheless have enough hair to "look like a longhair"!
Of course all of your hair strands will never simultaneously achieve terminal length
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ANGELA CHRISTIANO, PhD: You do hear people say, "My hair only grows to this length, and never any longer," and then you hear people who say, "I once grew my hair down to my ankles, and it could have kept going." It's believed that the length of anagen, the length of the growth phase, is actually different in different people, and we don't know exactly what might determine that, although of course we believe it's genetic.