# never underestimate the power of the human libido

As I was walking into my building today, a recurring thought hit me, one that was spurred by the opening scenes to the movie Amelie a few years back: Just how many people are having sex around the world at any given point in time?  Yeah, so, I’m weird, big deal!

This didn’t occur out of the blue – I’m teaching a class on the sociology of human sexuality right now and will be talking about frequency of sexual intercourse next week.  As I was preparing my lecture notes for that discussion, it must have triggered this thought again deep in the recesses of my bizarre mind and, for some reason, it surfaced as I was walking into the building.  With about 3 or 4 minutes to think about it before I got to my office, I realized that I might just be able to actually calculate that number.  So, I sat down with my trusty spreadsheet program (OpenOffice, of course), a few reference books, and web access, and tried to come up with some numbers.

First off, thanks to Tom Smith (2003), we have decent data on the frequency of sexual intercourse of people of different ages in the US:

 age coital acts per week (US) 0-9 0 10-17 0.5 18-29 2.1 30-39 1.7 40-49 1.4 50-59 1 60-69 0.6 70+ 0.3

Now, just so it’s clear up front, he only actually gives numbers for people over 18.  So, I estimated that people between 10-17 would average .5 acts per week (mostly thanks to those above 15) and assumed those below 9 would have 0.  I needed those numbers to make my estimates more accurate.

Using US Census Bureau data, I looked up a world population pyramid to get a sense of how many people fall into these age ranges.  Here’s a rough estimate that is close to accurate:

 age world population in 2002 (in millions) 0-9 1,240 10-17 1,216 18-29 1,060 30-39 920 40-49 740 50-59 520 60-69 340 70+ 180 Total 6,216

I only needed one more bit of information to make the calculations: the average length of sex.  I found various estimates online, ranging from 2 minutes to 25 or so.  I went with what I thought would be a good average, around 10 minutes.

Using all of the above information, you can actually calculate the number of coital acts per week and per day:

 age number of coital acts per week number of coital acts per day 0-9 0 0 10-17 608,000,000 86,857,143 18-29 2,226,000,000 318,000,000 30-39 1,564,000,000 223,428,571 40-49 1,036,000,000 148,000,000 50-59 520,000,000 74,285,714 60-69 204,000,000 29,142,857 70+ 54,000,000 7,714,286 Total 6,212,000,000 887,428,571

Combining this with the average length of sex, you can then make an estimate of the number of coital acts at any given minute if you divide the number of coital acts per day by 144 (24 x 6; you would multiply by 60 for every minute, but considering each act of sex lasts 10 minutes on average, you need to account for overlap, so you only divide by an additional 6).  This means, the answer to my question is:

 age number of coital acts any given minute (assuming average length is 10 minutes, which means there is overlap) 0-9 0 10-17 603,175 18-29 2,208,333 30-39 1,551,587 40-49 1,027,778 50-59 515,873 60-69 202,381 70+ 53,571 Total 6,162,698

About 6 million people are having sex right now!  (I’ll let you provide your own mental images!)

Now, I did these calculations pretty quickly, so it’s certainly possible that my math is off somewhere.  And keep in mind that this is just an estimate, but I’m thinking it’s pretty close to accurate. There is also the problem that the frequency of intercourse numbers are for the US, which means they could be way off for the rest of the world, though I’d guess they are probably close to about average for the world (higher in some countries, lower in others).

The beauty of having these numbers is that you can now calculate how many people are having sex in given regions by turning them into rates:

• for every 1,000 people in a given region, there will be, on average, 999.36 coital acts per week (thank the 18 to 49 year-olds for doing more than their part)
• for every 1,000 people in a given region, there will be, on average, 142.77 coital acts per day
• and for every 1,000 people in a given region, there will be, on average, .99 people having sex at any given minute of the day (I image it’s kind of odd being that .99 of a person)

So, just for fun, here are some numbers for places I’ve lived:

• right now, in Morgan County, UT, where I grew up, there are 7.8 people having sex (pop. 7,906)
• here in Tampa, FL there are 382 people having sex right now (pop. 382,060)
• in Costa Rica there are  4,133 people having sex right now (pop. 4,133,884)

How many people are having sex where you live?

References:

Smith, Tom. (2003). American sexual behavior: Trends, socio-demographic differences, and risk behavior. University of Chicago, National Opinion Research Center, GSS Topical Report No. 25.

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