It always feels like too many, and until now it's been pretty hard to pin down an exact figure. That is, until Facebook came along and neatly organised our social lives for us.
Using an application and some manual data entry, I unleashed the inner geek and finally put an exact number to a question that has been nagging at me for a while: am I being left alone while everyone I know is partying up a storm in London?
As Facebook users often join the incorrect network, or have none at all, it's not really enough to count the network numbers that are shown on your friends list. You need to do the tally by hand.
This is made simple by a Facebook application called FriendsCSV which gathers a list of all your friends and emails you the resulting file in a format that can be opened using Microsoft Excel.
On opening the file, I found that the 'current_location' field was blank, but the 'affiliations' field contained the network data. Perfect, except that it's often wrong.
So I scanned the list and filled in the blanks, dividing people into those that have emigrated, those that are leaving soon and others that are just working overseas.
The results were a little bit of a shock. As it turns out, a whopping 33.4% of my Facebook friends fall into one of the above categories! This doesn't include my friends who were not born in South Africa.
It seems like a high number, but I wonder what the tally would look like for people of other nationalities. Is it common for all people to have a third of their friends leave, with most of them never coming back?
It's difficult to say, but I'd guess that the brain drain in South Africa leaves us worse off than most first world countries, but possibly a lot better off than the rest of Africa.
Just look at the same stats for a Zimbabwean, for example.
How many of your friends do you think are overseas? And does it bother you?