You are here

Probing the numbers of love

Thursday, October 29, 2015
Dr Hannah Fry believes that mathematics can offer a new of looking at something as mysterious as love.

Review by 

Kevin Baldeosingh

How do you know when you’ve found Mr or Ms Right?

Most people would probably give some version of “You just know”. Unfortunately, reliance on intuition in love (or most important matters) has been shown to be an inefficient way to make decisions. Luckily, there is another method. 

“Mathematics can offer a new of looking at almost anything—even something as mysterious as love,” writes Dr Hannah Fry in this charming treatise.

For example, a mathematical formula can tell you exactly how to proceed if you want to settle down with the right person. There is in maths something called the “optimal stopping theory”, which basically tells you the best time to make a choice. Applying the formula to dating, Fry writes: “If you are destined to date ten people in your lifetime, you have the highest probability of finding The One when you reject your first four lovers. If you are destined to date 20 people, you should reject the first eight.”

Of course, you might not know how many people you are likely to date in your lifetime, especially if you are a cricketer or model. But the formula can also be applied from an age perspective. So if you start dating at 15 and would like to settle down by 40, then, says Fry, “In the first 37 per cent of your dating window (until just after your 24th birthday) you should reject everyone: use this time to get a feel for the market and a realistic expectation of what you can expect in a life partner. Once this rejection phase has passed, pick the next person who comes along who is better than everyone who you have met before.”

Mathematics also explains why so many attractive women are still single in their 30s and 40s. “The game of dating is mathematically equivalent to what happens in a particular kind of auction where bidders submit sealed bids and no one knows the bid of any other participant,” Fry explains. The man is the prize, a strong bidder is a good-looking accomplished woman and a weak bidder a less attractive woman. Fry notes that a strong bidder is less likely to make a strong bid (meaning she will make less effort to win the man) since “she knows that another, better man is probably waiting for her just around the corner.” 

But the less attractive woman goes all out, and gets the prize. Over time, this leads to a smaller pool of decent men, and a larger cohort of smart beautiful women vying for these men. This is called the “Bachelor’s Paradox”.

And what about when you are actually in a relationship: can maths help you stay together? In fact, there are actually two equations that calculate the amount of negativity in a relationship. 

“The most successful relationships are the ones with a really low negativity threshold. In those relationships, couples allow each other to complain, and work together to constantly repair the tiny issues between them,” Fry writes.

Now, if you think all this scientific calculation is terribly unromantic, consider what it means: by relying solely on your intuition, you are more likely to end up in a broken or unhappy relationship, whereas by using some science and mathematics, your chances of a long-term and satisfying relationship are increased. And what could be more romantic than that?


​The Mathematics 

of Love

Hannah Fry.

TEDBooks, 2015.

ISBN 978-1-4767-


128 pages.


User comments posted on this website are the sole views and opinions of the comment writer and are not representative of Guardian Media Limited or its staff.

Guardian Media Limited accepts no liability and will not be held accountable for user comments.

Guardian Media Limited reserves the right to remove, to edit or to censor any comments.

Any content which is considered unsuitable, unlawful or offensive, includes personal details, advertises or promotes products, services or websites or repeats previous comments will be removed.

Before posting, please refer to the Community Standards, Terms and conditions and Privacy Policy

User profiles registered through fake social media accounts may be deleted without notice.