- A team analyzed six billion calls ( full study ) made by 35 million people and categorized relationships based on how frequently the subjects called each other
- They found that their subjects had an average of 4 people in their closest circle, 11 in the next, 30 in their third layer and 129 in their outermost circle of friends
- Who are your five best friends?
These highlights are from the source article:
Phone call study concludes we can only have five best friends