How Many Friends Do You Need? Research Says Your Brain Has a Surprising Limit

I just counted my close friends. The ones I’d actually call if I needed help moving, or who I’d want to know if something truly important happened in my life.

The number came to seven.

Not 500 Facebook friends. Not 1,200 LinkedIn connections. Not the however-many people I’ve exchanged business cards with over the years.

Seven.

Turns out, that might be about right—or at least, it’s well within the limits of what my brain can actually handle. And if a decades-long scientific debate is any indication, yours too.

The 150-person limit

British evolutionary psychologist Robin Dunbar has maintained for more than three decades that humans cannot maintain a social network beyond 150 people. This famous threshold—known as Dunbar’s Number—represents everyone from your closest family to people you wouldn’t feel embarrassed running into at an airport at 3 a.m.

Beyond 150, Dunbar told The Wall Street Journal this week, those become “one-way relationships.”

Of those 150, just five people are the family and friends you feel closest to, and ten are people you see at least once a month. Some 50 others are people you’d invite to a birthday party, and 100 more would be guests at your wedding.

The theory comes from Dunbar’s research comparing primate brain size to social group size. The bigger the neocortex—the part of the brain responsible for language and memory—the larger the network, Dunbar has posited.

The pushback

Not everyone agrees. Swedish researchers argued in 2021 that there is no cutoff number at all, finding that comparing humans to other primates ignores key differences—chimpanzees need to fend off predators and fight for food, while humans largely don’t anymore.

When they repeated Dunbar’s analyses using modern statistical methods and updated data, the results varied wildly—average group sizes ranged from 16 to 109, with confidence intervals so enormous (between 2 and 520 people) that specifying any one number seemed futile.

Dunbar called that research “absolutely bonkers,” telling The New York Times he marveled at the Stockholm University researchers’ “apparent failure to understand relationships.”

And what about social media?

Dunbar says the rise of Facebook and Instagram has done little to change his findings, which he first published in 1993:

“If you look at the frequency of postings on social media, frequency of telephone calls, the frequency of face-to-face contacts, the frequency of texting, you see the same layers.”

Why this matters

Whether Dunbar’s specific number is right or not is probably less important than the broader point about friendship and connection.

An oft-repeated 2023 report from then-U.S. Surgeon General Vivek Murthy found that loneliness and social isolation raise the risk for premature death by nearly 30 percent—comparable to smoking 15 cigarettes a day.

Strong social connection protects against heart disease, dementia, and stroke, according to the Centers for Disease Control and Prevention.

More than 20 percent of American adults now report feeling lonely, according to Harvard research. At any given moment, about one out of every two Americans is experiencing measurable levels of loneliness.

The good news? You don’t need 150 friends to get the health benefits. Dr. Jeffrey Hall, a professor at the University of Kansas, told The New York Times that all you really need is one friend to make a difference.

“Going from zero to one is where we get the most bang for your buck, so to speak,” Hall said. “But if you want to have the most meaningful life, one where you feel bonded and connected to others, more friends are better.”

The bottom line

So how many friends do you need? Maybe it’s not about hitting some magic number—whether that’s 5, 50, or 150.

Maybe it’s about having enough real connections that you’re not lonely. Enough relationships where the investment flows both ways. Enough people who would actually show up if you needed them.

And based on the health research, maybe it’s about recognizing that those friendships aren’t just nice to have—they might be as important to your longevity as not smoking or exercising regularly.

Which means: If you’ve been meaning to call that friend you haven’t talked to in months, this might be your sign.

I mean, you’re probably reading this on your phone. How much extra effort would it take?

Your brain—and your heart—will thank you.