On Facebook, it seems that just about everyone is a friend of a friend somewhere down the line. There are plenty of occasions where Facebook users will make a new connection, only to find that they have some very surprising mutual friends.

So how unlikely is it, for example, that your new co-worker is friends with your best friend from elementary school? More likely than you may think.

A new study from the social network and its data team has found that 99.6 percent of all people on the social network can be connected within five steps, or six relationships. Ninety-two percent can be connected within four steps.

According to the company’s data team, in 2008 the average amount of separation between any two given people on the network was 5.28 steps. Just three years later, it’s 4.74.

The network said that 84 percent of all connections are between users in the same country — connecting within three steps. The study also found, perhaps not so surprising, that users tend to have friends who are the same age as they are. That trend also holds true for older Facebook users.

The social network says is has a sample size of 721 million people, or a little over 0ne-tenth of the estimated world population. The data team said there are 69 billion friendships on the network.

(The Washington Post Co.’s chairman and chief executive, Donald E. Graham, is a member of Facebook’s board of directors.)

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