SINGAPORE – Ms Chloe Liem feels that her $3,950 Cartier Trinity earrings are “practically free”.

The 20-year old rationalises her purchase like this: She initially wanted a pair that costs $5,250, so getting a cheaper set makes it feel like she is saving $1,300 from the get-go.

She also has $1,000 in mall vouchers, meaning she has to fork out only $2,950.

Whipping out a calculator on her TikTok video, the content creator deadpans that if she wears the earrings daily for the next four years, it will cost about $1 apiece each time she wears them.

Justifying big-ticket spending like this is known as “girl math”, said Ms Liem, referring to a new viral TikTok trend, which began in New Zealand but has since gained popularity around the world.

The term was popularised in July when hosts on a New Zealand radio show called Fletch, Vaughan and Hayley told a listener that her NZ$330 (S$267) dress purchase was reasonable since she was going to wear it thrice.

“So this is not a NZ$330 dress, it’s NZ$110,” said radio deejay Hayley. 

Rationalising spending this way is girl math, the deejays said.

The trend is catching on here. Ms Liem’s video, posted on Wednesday, has gained over 3.3 million views and 382,000 likes.

Speaking to The Straits Times, Ms Liem said she made her video to entertain viewers. She added that it was a fun way to talk about what she says are irrational spending habits, and how people think when they buy things.

“Anything is possible with girl math,” said Ms Liem, adding that the concept might seem silly, but it is still entertaining and fun to use.

Girl math can take many forms. To Ms Liem, it can also mean buying an extra item to qualify for free shipping when shopping online, as she would get an additional purchase and complimentary delivery out of it.

It can also mean thinking of refunds as “free money” to buy other things because “in my head, I’ve already spent that money”, she added.

Ms Nicolette Wee, 23, a business acquisition associate, gave another example: Her workplace provides lunch, making her feel like she has “extra money” to get herself a treat each day.

“I know I am deluding myself, but it is silly and fun for us (girls),” she said.

Even some men are into it.

Mr Justin Sng, 26, who talks about financial management on his TikTok account, said girl math helped him justify a $3,000 suit he had bought. 

“I told myself that I am probably going to wear this suit for around 10 years, and if I wear it twice a week, it’d cost only $2.88 per wear,” said Mr Sng, 26, half in jest.

“That’s girl math to me – a cheeky and fun way to justify spending exorbitant amounts of money on wants.”

Experts said girl math taps into emotions to justify financial choices.

Dr Seshan Ramaswami, associate professor of marketing education at Singapore Management University, said consumers are driven to buy things because of the emotional high they get from making purchases.

He said it was “all right” if these were small purchases but cautioned consumers to be conscious because these “same biases can affect big purchases, investments or other financial decisions”.

For consumers who think refunds are free cash, Dr Ramaswami said these people are inclined to think this way because they might not feel they incurred a loss by returning a product they did not like. So the money they got in return would feel like a “perceived gain”.

Experts and the young people ST interviewed warned others not to take the fuzzy accounting of girl math seriously and pointed out that it was important to practise good financial planning.

Senior financial consultant Kayley Chua, 27, said thinking of refunds or discounts as “free money”, as espoused by users of girl math, could encourage impulsive spending and reduce savings that can be put away for long-term financial goals.

“It is crucial to avoid unnecessary spending solely based on the perception (of getting) a good deal,” Ms Chua said.

Ms Lorna Tan, head of financial planning literacy at DBS Bank, said people should be wary of being lulled into thinking that they have made gains or savings when it might not be the case in reality.

“Girl math looks fun, and like most fun things, should not be taken too seriously,” she said. “Managing finances well requires knowledge, discipline and deliberate actions that go beyond the trend.”