The number of friends we really need to be happy - and why

The gang in Friends knew the magic number. Photo / Supplied

For many, lockdown had a profound impact on the number and nature of our friendships – but your inner circle needs to be a certain size.

How many friends do you have? Not counting the hundreds on Facebook or the names gathering dust in your address book. But real friends, the ones cast in stone. The kind who would lend you $100 without asking why, or put you up if you were kicked out of your house.

According to the experts, the pandemic years – and their aftermath – have changed the number and nature of our friendships.

Anthropologist Prof Robin Dunbar feels he can put a number on it: five. No matter how much of a social butterfly you are, you can count your real pals on one hand, he says. To that he says you can add an optimal number of 15 "good friends", the kind you see one-on-one regularly, 50 "friends", the kind of people you would see in a group and would join for a drink if you bumped into them in the pub, and up to 150 "meaningful contacts".

"We're always on the lookout for new and better friends, but lockdown has had a big effect in making people reevaluate," says Dunbar. "Perhaps they've decided the time has come to part with some and therefore there's an empty slot to fill."

Prof Dunbar's latest research is an exact formula for friendship: new friendships take 34 hours of one-on-one time to cultivate, in which you'd spend an ideal duration of three hours and four minutes per interaction together over the course of six months. Note that this is to turn an acquaintance into a friend, not one of the close friends that makes up your inner circle of five – to do that, you'd have to dedicate 90 hours, according to a 2018 University of Kansas study.

The forecast for British friendship was already gloomy before the pandemic. Three million people said they feel lonely "often or always", according to the Government's 2019 community life survey. But the average British adult lost four friends over the course of the pandemic, according to one poll.

Fading friendships

Covid also gave people more grounds for disagreement: over adherence to social-distancing rules, for example. Plenty of people lost relationships in the cracks, which has left us with a friendship frenzy of people recruiting for a vacant spot. Dunbar's latest research shows that 66 per cent of people are actively interested in making new friends, while 54 per cent of people think they have fewer friends than they did a decade ago.

This is just the latest of Dunbar's studies on friendship, prompted by his early research with primates. Across species, Dunbar found that the ideal social group size correlated with the size of the brain. For humans, "Dunbar's number" came out at 150, with just a handful in our inner circle.

Making new friends in adulthood is no mean feat, even with the ease of online communication. Dunbar says social media is a "sticking plaster" which can slow down the rate of attrition for faltering friendships, but rarely foster meaningful new ones without face-to-face connection.

It may take 34 hours to solidify a new friendship. "But it can't just be bumping into them on the street," says Dunbar. "It's more about roughly a dozen more substantial meetings where you spend time face to face."

Periods of transition

How that manifests is – unsurprisingly – different for men and women. "Who you are is more important than what you are, for women," says Dunbar. "Male friendships tend to be more activity based. It's more important to be part of a club, which could be anything from playing sport to sitting in the pub."

The biggest periods of friendship transition are in your late 20s and early 30s, when you might start a family and become more selective, says Dunbar. Passing the age of 65 is also a flashpoint. Studies are pretty much unanimous in showing that the danger period is post-retirement.

"You find that friends move away – they retire and go live near their children and grandchildren," says Dunbar. "The other big difference between the sexes is the effect of divorce. The men's friends tend to morph into the husbands of their partners or wives.

So when a divorce happens, suddenly you've lost half your friendship group." Then, he says, you're into the period where your friends start dying off.

And so we need to build new friendships. You can put a number on how much time you need to spend with someone in order to turn them from an acquaintance to a friend. But how do you choose the people who you're willing and able to invest that time in?

Dunbar has previously identified the seven pillars of friendship – a check-box exercise for finding those you'll click with. The pillars are: language or dialect; growing up in the same place; education or career; hobbies and interests; worldview, politics and religion; sense of humour; musical taste. Based on this research, if you have a couple of these in common with someone, they're eligible to make the shortlist.

It's long been known that good friends are vital not only for psychological wellbeing but for physical health. Research published in 2020 by the National Academies of Sciences, Engineering and Medicine found that social loneliness was associated with a 50 per cent higher risk of developing dementia and a 32 per cent higher risk of stroke.

"We have evidence from all around the world that shows the number and quality of friendships you have – in particular that inner core of best friends – has a bigger impact on your mental and physical wellbeing," says Dunbar. "It will also affect how long you will live, more than anything else your GP could do."

Friendship in numbers

Average number of friends:
• 18 to 24: 7.6
• 55 and over: 4.8

Where you met your friends:
• At work: 44 per cent
• At school: 41 per cent

Making friends:
• Time needed to turn an acquaintance into a friend: 34 hours
• Time needed to turn a friend into a confidante: 90 hours