Jeffrey Hall, a teacher of Communications from the University of Kansas (KU), has used his research to define the exact amount of time necessary to make friends with someone. He's also found how long it will take to deepen a relationship. His new study found that it takes around 50 hours of time together to go from being someone's acquaintance to a casual friend. It takes about 90 hours to go from being a casual friend to a friend, and more than 200 hours before considering someone a close friend or best friend.
But it isn't spending just any kind of time together that deepens a friendship—hours spent working together, for example, don't count as much as hours spent getting to know someone by hanging out, joking around, playing video games, and doing more playful activities. The study explains that these kinds of activities help us to form a deeper connection with someone. "We have to put that time in," Hall said. "You can't make friends without any effort."
The results of the study come from the analysis of 355 responses to an online survey from adults who said they had moved in the last six months and were looking for new friends in their new environment. Survey participants were asked about new relationships as well as hours spent together and activities they did. They were then asked to rate their resulting relationships according to one of four stages: acquaintances, casual friends, friends and close friends.
The main conclusion that Hall came to is that making close friends takes serious effort. So if you want to have some best friends, you have to know that spending time with someone is the most important thing.