• by Erik Sass , Staff Writer @eriksass1, July 15, 2013

Facebook users drastically underestimate how many people their content reaches via the social network, according to a new study from researchers at Facebook and Stanford University, titled “Quantifying the Invisible Audience in Social Networks.”

The study, which analyzed posts from 222,000 Facebook users in June 2012, found that on average users’ estimates of the number of people they reach via posts are just 27% of the actual figures, meaning users are reaching roughly four times as many people as they think.

For any specific post, Facebook users estimated the total audience at a median 20 friends, while the actual audience figure was a median 78 friends; study participants rarely estimated that any of their posts reached over 50 friends, when in fact this was a common occurrence. On a monthly basis, users estimated their total audience (meaning everyone who had read one of their posts in the past month) at a median 50 friends, when in fact they reached a median 180 friends. On a monthly basis, each user reaches an average 61% of their Facebook friends, while each post is read by 35% of those friends, on average.

Part of the reason for the substantial discrepancy between actual and perceived audience size may be that users try to gauge reach based on the number of “likes” or comments generated by a post -- the second-most-popular strategy for estimating audience (after simply guessing). Typically only 20%-40% of friends who saw a post went on to like or comment on it, however, and the study found that estimates based on these measures (e.g. “the total audience is the number of ‘likes’ times four”) were no more accurate than simple guessing.

In terms of satisfaction with audience size, only 3% of study participants said they wanted to reach fewer people, while just under half said they wanted a larger audience, and half said they were satisfied with their current audience size.