# Hair... and another totally unrelated question **URL:** \ **Category:** Factual Questions\ **Created:** [May 16, 2001, 6:16am UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578 "2001-05-16T06:16:21Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![MagicalSilverKey](https://avatars.discourse-cdn.com/v4/letter/m/8797f3/32.png) [@MagicalSilverKey](https://boards.straightdope.com/u/MagicalSilverKey)\ **Post date:** [May 16, 2001, 6:16am UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/1 "2001-05-16T06:16:21Z")
How much total hair does the average human produce in a lifetime? This includes: [li]head hair (male and female)[/li][li]body hair (male and female)[/li][li]cumulative lifetime weight of hair in each category (preferably stated in pounds/ounces)[/li][li]cumulative lifetime length of hair in each category (preferably stated in feet/inches)[/li] Second totally unrelated question: How many hours and minutes total during an average person’s lifetime are spent going to the toilet? ---
**Author:** ![Protesilaus](https://avatars.discourse-cdn.com/v4/letter/p/82dd89/32.png) [@Protesilaus](https://boards.straightdope.com/u/Protesilaus)\ **Post date:** [May 16, 2001, 8:05am UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/2 "2001-05-16T08:05:27Z")
> [@](#): > > \*Originally posted by MagicalSilverKey \* > \*\*How many hours and minutes total during an average person’s lifetime are spent going to the toilet? \*\* Assuming a total toilet time per day of 20 minutes, we have: 20 minutes/day x 365.25 days/year x 75 years/lifetime = 547,875 minutes = 9,131.25 hours = 380.46875 days About 1 year, 15.5 days. With an average of 30 minutes/day, it comes to 570.703125 days, or almost a year and seven months. ---
**Author:** ![MagicalSilverKey](https://avatars.discourse-cdn.com/v4/letter/m/8797f3/32.png) [@MagicalSilverKey](https://boards.straightdope.com/u/MagicalSilverKey)\ **Post date:** [May 16, 2001, 2:12pm UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/3 "2001-05-16T14:12:57Z")
Protesilaus, Damn! I always knew was a big ol’ waste of time, but I didn’t know it was that significant. Why can’t I become a fuel cell powered cyborg who just emits harmless h2o vapor exhaust…arrrgh! ---
**Author:** ![missdavis102](https://avatars.discourse-cdn.com/v4/letter/m/7feea3/32.png) [@missdavis102](https://boards.straightdope.com/u/missdavis102)\ **Post date:** [May 16, 2001, 3:02pm UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/4 "2001-05-16T15:02:33Z")
Cumulative length of hair over a lifetime (Sorry, I can only do this in metrics) Assuming 2.5 million follicles per head with average rate of 3.5millimeters per week over lifetime of 75 years (3900 weeks) plus 1 million follicles per body (hairy) with average rate of 3.5 mm per week over lifetime you get 47775 million mm of hair. Or about 477.75 kilometers. That’s about 287 miles. Same assumption per head plus .5 million follicles per body (not-so-hairy) with average rate of 2.5 mm per week over lifetime you get 34125 million mm head plus 4875 million mm body to yeild 39,000 million mm of hair, or about 390 km. That’s about 234 miles. Of course these are very rough estimates, failing to take into account either the follicularly challenged or the pelt people among us. And the figures for growth rate are listed for Europeans, not other groups. But still, you have to wonder - where does all that hair go? Hair fibers decompose much more slowly than most other human tissue (due to all the keratin, I think), so I always figured there would be a terminal hair buildup at some point that will clog all the world’s drains and set civilization back quite a few years. Multiply and average of 260 miles times 6 billion people and what do you get? I predict Hairball Earth. ---
**Author:** ![cher3](https://avatars.discourse-cdn.com/v4/letter/c/da6949/32.png) [@cher3](https://boards.straightdope.com/u/cher3)\ **Post date:** [May 16, 2001, 4:04pm UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/5 "2001-05-16T16:04:07Z")
These are interesting speculations, but I just have to say that if you are spending 20 minutes a day on the toilet, you need to decrease your fluid intake or increase your fiber intake. ---
**Author:** ![choosybeggar](https://avatars.discourse-cdn.com/v4/letter/c/8c91f0/32.png) [@choosybeggar](https://boards.straightdope.com/u/choosybeggar)\ **Post date:** [May 16, 2001, 10:18pm UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/6 "2001-05-16T22:18:42Z")
> [@](#): > > \*Originally posted by missdavis102 \* > \*\*Assuming 2.5 million follicles per head \ > 1 million follicles per body (hairy) > \*\* Where in the Sam Hill did you get these figures. In Med School the quoted number for head hair was about 10,000-20,000 or about 100X less than the figure you use. I’ve never seen a figure for body hair. I can’t find a cite right now but consider this: assume that the hair-covered area of the scalp is 15X15 cm (probably too large, but I’m feeling generous). That area therefore is 225cm[sup]2[/sup]. Using the hair follicle count you provide, there need to be 2,500,000 follicles over the 225cm[sup]2[/sup] area or 11,000 hair follicles per square centimeter. Using 20,000 follicles per head, the number is 90/ cm[sup]2[/sup]. Which sound closer to reality? ---
**Author:** ![choosybeggar](https://avatars.discourse-cdn.com/v4/letter/c/8c91f0/32.png) [@choosybeggar](https://boards.straightdope.com/u/choosybeggar)\ **Post date:** [May 17, 2001, 9:40am UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/7 "2001-05-17T09:40:07Z")
Alright, I found a cite for hair density [here](http://www.keratin.com/aa/aa010.shtml) > [@](#): > > Research on humans suggest that active hair fiber growth production from scalp hair follicles may last from 500 to 1800 days. In normal haired individuals about 80% of hair follicles are in a growth phase with the remaining 20% in a regression or resting phase. Hair follicle density on the scalp is 200-300/cm square, that is about 100,000 to 150,000 hairs total. The scalp hair fiber growth rate is between 0.3 to 0.35mm a day. For the most part, the studies were done with male volunteers, but a few other studies indicate similar results for women too. > > If you put it all together in a calculation, the research would suggest that the maximum length scalp hair can grow to is between 20 and 60 centimeters and the sum total length of hair produced each year is about 9km! However, from the picture below you can see that some people are able to grow their hair much longer. The upper limit to scalp hair length is determined by our genes. Some people have genes for short hair, others grow hair much longer. So I was a little off on the hair density thing, sue me. I checked their 20 km/year figure and it works out. Assuming a 75 year lifespan, that’s 1500 km or 900 miles. However from the above passage, we learn that at any moment, approximately 20% of the follicles are resting. So it may be more appropriate to take only 80% of the above figures. And since you asked for weight, dear OP, when I get to work today, I’ll pluck out one of my few remaining, treasured follicles, measure it’s length and then it’s weight on an analytical balance. ---
**Author:** ![Dijon\_Warlock](https://avatars.discourse-cdn.com/v4/letter/d/a9a28c/32.png) [@Dijon\_Warlock](https://boards.straightdope.com/u/Dijon_Warlock)\ **Post date:** [May 17, 2001, 9:47am UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/8 "2001-05-17T09:47:40Z")
Hey, kids! What time is it? It’s time to “Stump Beekman!” "The lemon shark grows a new set of teeth every two weeks. "Your brain is 80% water. **"The average person has over 100,000 hairs on their head.** "A housefly lives only for an average of two weeks. "Fish _do_ get seasick, when kept on a boat. “When you’re Beekman, you know these things, ha ha!” Every freakin’ ten minutes in the afternoons. ---
**Author:** ![choosybeggar](https://avatars.discourse-cdn.com/v4/letter/c/8c91f0/32.png) [@choosybeggar](https://boards.straightdope.com/u/choosybeggar)\ **Post date:** [May 17, 2001, 12:47pm UTC](https://boards.straightdope.com/t/hair-and-another-totally-unrelated-question/65578/9 "2001-05-17T12:47:36Z")
Ok, I weighed a hair (not to self-get life). A precious 9cm long strand came in at 0.59mg. Assuming I am the model human, that’s 6.6mg/m hair. Since a lifetime of hair growth produces 1500km, the weight of said hair is 9.8kg or 21.6 pounds. Guess this means weight gain cannot be attributed to hair loss.