Rise of ‘girl math’ and ‘boy math’: Gen-Z shoppers think using cash doesn’t count as spending, that anything under $5 is effectively FREE and that riding a $400 bike 400 times means it only costs a dollar

New ‘girl’ and ‘guy’ math phenomena are taking TikTok by storm as Gen Z shoppers oddly claim that using cash doesn’t count as spending money and anything under $5 is effectively free .

Consumers are sharing their often illogical excuses for shopping under hashtags. In dozens of videos, people find ways to convince themselves that they’ve either saved — or even made — money while buying things.

TikTok user McKenna explained the rules of ‘girl math’ simply as: ‘Anything under $5 is free, anything I buy with a gift card is free.’

“If I buy something and then return it, I’ve made money. Going to an event or concert is free because I bought the tickets so long ago, it doesn’t even count.’

‘Girl Math’ helps women justify the purchases they’ve made and often looks at ways consumers can convince themselves they’ve saved money.

“(If I) return something to Zara for $50 (and) buy something else for $100, it only cost me $50,” Samantha Jane, 28, said in a TikTok.

In an interview, Samantha Jane said: “Girls’ math is fun logic. We can justify things as we want in our heads – we can make our own rules. It reframes the narrative and removes the shame around spending money.’

User Asia Jackson posted the explanation of ‘girl math’ to make money.

“If I put $25 in my jacket pocket and forget about it, and then a few months later I put on my jacket and find $25 in my pocket, I’ve made money.”

On the other hand, ‘boy math’ takes a more frugal approach to shopping compared to the splashes of ‘girl math’.

TikToker Mads Mitch explained, ‘guys math isn’t wasting your money on frivolous things. It’s (for) being economical, it’s saving.’

Mads claimed that men often increase their height in an attempt to attract the attention of women and mocked their use of 7 in 1 shampoo.

The ‘boy’ and ‘girl’ math is an online trend where users share their shopping rationales. Many people find ways to convince themselves that they are saving money

TikTok user Mad Mitch posted a video explaining ‘boy math’. She said ‘boy math’ takes a more frugal approach to shopping compared to the splurge of ‘girl math’.

‘Number one. If you’re 5ft8in, legally, legally your medical records would say you’re 5ft8in, you’re actually sort of 5ft10in,” said Mads.

And if you’re 5ft10in, you’re actually kind of six foot. If you’re six feet, you’re actually kind of 6ft2in!’

Josh Benevides used the guy’s math to justify splashing out $400 on an exercise bike—saying that if I ride it 400 times, it only costs $1 per ride.

She added: “There’s no way a 7 and 1 shampoo is telling the truth. You are not doing seven things perfectly. There’s just no way. But don’t worry, because it’s only $3.99.’

Josh Benevides, 47, co-owner of a used sporting goods store in Juneau, Alaska, told Wall Street Journal he hesitated to buy an exercise bike for physical therapy after tearing his ACL, but justified the $400 price tag with an equation.

“If I ride the bike 400 times, it only costs me a dollar per ride,” Benevides said. He claimed to have ridden the bike at least 4,000 times, so now it’s like ‘riding on a dime’.

Stacy Francis, president and CEO of financial advisory firm Francis Financial in New York, said the concepts have become fashionable because they are similar.

“Whether you’re male or female, when you spend small amounts like $5, your brain doesn’t register that it could be a lot of money. Although, in reality, $5 a day is $1,825 a year,” said Francis.

A father-daughter duo left the internet in stitches after the 18-year-old posted videos of her trying to explain ‘girl math’ to her dad.

Marley Brown, 18, shared the concept of ‘girl math’ with her increasingly frustrated father.

Marley Brown said, ‘If I buy a skirt, and then I return the skirt because it doesn’t fit or something, the money I get back is like free money.’

“No,” her father replied. “Then you could do that 1,000 times, and then you’d have 1,000 free money skirts, which is not true.”

Another such instance was ‘anything I buy with cash is free,’ Marley testified, to which her father disagreed, saying, ‘No.’

But Marley answered emphatically, ‘Yes.’

“No, that’s not how money works,” her father insisted.

Whether you practice ‘boy’ or ‘girl’ math, physical justification can help ease the pain most people face at the checkout.

In September, the annual rate of inflation remained stable, with prices increasing by 3.7 percent, mainly thanks to the cost of food and energy.