How long it really takes to turn a good friend into a great friend (according to science).

The older you get, the harder it seems it is to find friends. The kinds of friends who won’t mind if you suggest hanging out at home with a bottle of wine and the latest Netflix series instead of going out. Or the kinds of friends you can text “my period is making my life hell on earth” to cancel plans instead of faking a “work emergency”.

The deeper into adulthood you go, the more distant the days of discovering your best friend because you happened to sit next to each other that one time in maths class seem.

And now, new research has confirmed the theory that making friends actually requires a) a lot of effort and b) quite the amount of time.

Jeffrey Hall, Associate Professor of Communication Studies at University of Kansas, conducted a study in which he calculated the exact number of hours it takes to go from casual acquaintance to ‘best friend forever’.

According to his results, it takes 50 hours from the moment you meet someone to become a ‘casual friend’ and 90 hours to become a ‘friend’.

And to be counted as someone’s ‘close friend’? Hall says you need to spend 200 hours or more with a person to reach that most sacred of friendship statuses.

And it's not just being in someone's presence that counts as time put towards a friendship: it's all about forming a connection, so hours spent hanging out, joking and visiting places together all count way more than the hours you spend sitting next to your colleague at work.

So how exactly did Hall calculate these hours? He and a colleague developed an interactive friendship tool, which, based on the answers to a few short questions, is able to predict the 'closeness' of a friendship. By analysing the answers of 355 respondents, the time when a friendship began to transition from one stage to another was pinpointed.

LISTEN: Friendship break ups are often harder to get over, but why don’t we talk about them as much? Post continues after audio.

And while putting in 200 hours of effort to become someone's close friend sounds like a lot, the study also found that the closer people get, the easier it is for them to spend time together.

"When people transition between stages, they'll double or triple the amount of time they spend with that other person in three weeks' time," Associate Professor Hall said.

And it's all about making getting to know someone - particularly if you think they would made a great, close friend - a priority.

"You can't make people spend time with you, but you can invite them," he said.

"Make it a priority to spend time with potential friends. If you are interested in a friendship, switch up the context. If you work together, go to lunch or out for a drink. These things signal to people that you are interested in being friends with them."