Note: This article about Facebook friends was originally published in 2012. The number of Facebook users has grown rapidly since then. If you’re interested in leveraging the power of Facebook for your business, you may be interested in Stikky Media’s social media management services.

It’s safe to share with friends of friends, right? I mean, you kinda know them. They’re the people you were introduced to at your girlfriend’s birthday party, or the ones you met in passing at the mall. It’s only 2 degrees of separation, so why not let them see all your photos?

Here’s why: Facebook users reach an average of 150,000 people through their friends of friends.

In case you need more reasons to lock down your profile and throw away the key, here’s what else the study found out:

A friend of a friend is probably not your friend

This one’s obvious. If a friend of a friend was really your friend, wouldn’t they be your friend? There’s no way you can possible know 150,000 people well enough to trust them with your personal life. Or even ask them out for coffee. So if your profile is set to share with friend of friends, you might as well make your entire profile public.

Facebook users make an average of seven new friends per month (3 initiated and 4 accepted)

Combined with the fact that the average Facebook user has 245 friends, this means you probably make over a thousand new friends of friends each month. Even if you subtract the people you are already friends with, that’s a lot fresh creeping on your profile.

Facebook users underestimate their number of Facebook friends

The study found that people think they have 18 fewer Facebook friends than what they actually have. They reported an average of 227 friends, but in reality had an average of 245. In other words, you’re reaching way more people than you think.

Your friends have more friends than you

The average person has 245 Facebook friends, but the average friend of that person has 359 Facebook friends. So while you may pick and choose your friends with care, your friends probably don’t.
 

Creeped out? Me too. If you’re guilty of over-sharing, make sure your default privacy is set to “Friends.” Then, click on Limit the Audience for Past Posts and make sure your How You Connect settings are where you want them to be.

Also, next time you’re posting a status update, click the dropdown menu next to the “Post” button and make sure it’s not set to friends of friends—or worse yet—public.