By At 20, friends seemed to appear almost by accident. You shared a dorm hallway, a class, a part-time job or a sports team, and somewhere along the way, a stranger became someone you’d call at 2 a.m.
At 50 or 60, it can feel like the machinery has broken down. You meet perfectly nice people at work, at the gym or through your kids, but the friendships never quite take. It’s easy to conclude that something is wrong with you. Research suggests the real problem is much simpler: time.
Counting the hours
In 2018, Jeffrey Hall, a communication studies professor at the University of Kansas, set out to measure something nobody had pinned down before: how many hours it actually takes to turn a stranger into a friend.
He ran two studies. In the first, he surveyed 355 adults who had moved to a new city in the previous six months and were looking for friends. He asked them to think of someone they’d met since moving and describe how much time they’d spent together, what they’d done, and how close they now felt. In the second, he followed 112 first-year students at the University of Kansas over their first weeks on campus.
Combining the results, he estimated that it takes roughly 50 hours together to move from acquaintance to casual friend, about 90 hours to become a friend, and more than 200 hours to become a close friend.
Not all hours count equally
The type of time mattered too. Hall found that hours spent hanging out, joking around or doing things together for fun pushed friendships forward. Hours spent working together didn’t count for nearly as much.
That helps explain a familiar adult experience. Some people in the study had spent hundreds of hours with coworkers and still called them acquaintances. Time spent by choice, outside the roles you’re obligated to play, is what seems to do the work.
Why adult life runs short on hours
Think about how much time young people spend together. Hall found first-year students who spent a third of their waking hours in a month with a single good friend. School, college and early jobs pile people into the same spaces day after day, with loose evenings and weekends to fill.
Later in life, that changes. Work takes up a big share of the day, family and household responsibilities claim much of the rest, and free time often comes in short, scattered blocks. At 200 hours, a close friendship would take a full year of seeing someone for four hours every week. Plenty of busy adults don’t see their oldest friends that often, let alone someone new.
The study didn’t look specifically at people over 50, and age itself isn’t the barrier. But the math helps explain why friendship often gets harder as life gets fuller. It’s not a sign that people have lost the knack. They just rarely get the hours.
The brain’s social budget
Hall’s work builds on a larger idea from evolutionary psychology and neuroscience. Oxford anthropologist Robin Dunbar proposed that humans can only maintain a limited number of meaningful relationships, famously around 150, partly because of the brainpower social life demands.
Keeping track of who’s who, what they think of you and what you owe each other is mentally demanding work. In Dunbar’s “social brain” view, the size of the human brain, and especially the neocortex, evolved partly to manage these relationships. Closer relationships take more investment, so we can only maintain a handful at the innermost level.
Hall describes time spent with others as a kind of strategic investment toward meeting our deep need to belong. Time is the currency the social brain spends on relationships, and there’s only so much of it to go around.
Friends on the same wavelength
Brain imaging research suggests that close friends may share more than time. In a 2018 study published in Nature Communications, researchers at Dartmouth College scanned the brains of graduate students while they watched a series of short videos. People who were close friends showed more similar patterns of brain activity than people who were further apart in the group’s social network.
That doesn’t prove that spending time together makes brains more alike, or the other way around. But it fits with the idea that close friends tend to see, interpret and react to the world in similar ways, and that kind of shared understanding takes time to build.
Finding the hours
None of this means making friends later in life is hopeless. It just means it works more like a long project than a lucky accident. Hall’s own advice is simple: you can’t force people to spend time with you, but you can invite them. If you mostly see someone in one setting, like work or the gym, suggest something different, such as lunch, a walk or a coffee.
Regular, repeated contact helps the most. Clubs, classes, volunteering and team activities can recreate some of the built-in time that school once provided. Choosing a few people and seeing them consistently tends to work better than meeting lots of people once.
The hours add up slowly. But if friendship hasn’t come as easily as it used to, the problem may not be you at all, just a calendar that hasn’t left enough room for it.
