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

The new phenomena of ‘girl’ and ‘boy’ math is taking TikTok by storm as Gen Z shoppers bizarrely claim using cash doesn’t count as spending money and anything under $5 is effectively free. 

Consumers are sharing their often illogical justifications for making purchasing under the hashtags. In dozens of videos, people find ways to convince themselves they have 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 but then I return it, I made money. Going to an event or concert is free because I purchased the tickets so long ago it doesn’t even count.’

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

 ‘[If I] return something at Zara for $50 [and] bought something else for $100, it only cost me $50,’ said Samantha Jane, 28, in a TikTok.

In an interview Samantha Jane said, ‘Girl math is fun logic. We can justify things however we want to in our heads — we can make our own rules. It reframes the narrative and takes away the shame around spending money.’

User Asia Jackson posted the ‘girl math’ explanation for making money.

‘If I put $25 in the pocket of my jacket and I forget about it, and then months later I put my jacket on and I find $25 in my pocket, I’ve made money.’

On the flip side, ‘boy math’ takes a more frugal approach to purchases compared to ‘girl math’s’ splurges.

TikToker Mads Mitch explained, ‘boy math is not wasting your money on frivolous things. It’s [about] being economical, it’s being thrifty.’

Mads claimed that men will often round up their height in a bid to attract female attention, and poked fun at their use of 7 in 1 shampoo.

‘Boy’ and ‘girl’ math is an internet trend where users share their justifications for making purchases. Many people find ways to convince themselves they are saving money

TikTok user Mad Mitch posted a video explaining 'boy math.' She said 'boy math' takes a more frugal approach to purchases compared to 'girl math's' splurges

TikTok user Mad Mitch posted a video explaining ‘boy math.’ She said ‘boy math’ takes a more frugal approach to purchases compared to ‘girl math’s’ splurges

‘Number one. If you are 5ft8in, by law, legally your medical records would indicate that you are 5ft8in, you are actually somehow 5ft10in,’ said Mads.

‘And if you’re 5ft10in, you’re actually somehow six feet. If you’re six feet, you’re actually somehow 6ft2in!’

Josh Benevides used boy math to justify splashing out $400 on an exercise bike - saying if he rides it 400 times, it only costs $1 a ride

Josh Benevides used boy math to justify splashing out $400 on an exercise bike – saying if he rides it 400 times, it only costs $1 a ride 

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

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

‘If I ride the bike 400 times, it only costs me a dollar a ride,’ said Benevides. He claimed to have rode the bike at least 4,000 times, so now it is like ‘riding for a dime.’

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

‘Regardless of whether you’re male or female, when you’re spending small amounts like $5, your brain doesn’t register that it could be a lot of money. Even though, in reality, $5 a day is $1,825 a year,’ said Francis.

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

Marley Brown, 18, broke down the concept of 'girl math' to her increasingly frustrated dad

Marley Brown, 18, broke down the concept of ‘girl math’ to her increasingly frustrated dad

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

‘No,’ her father responded. ‘Then you could do that 1,000 times, and then you’d have 1,000 skirts worth of free money, which isn’t real.’

Another case in point was ‘anything I buy with cash is free,’ Marley attested, to which her father disagreed, saying, ‘No.’

But Marley emphatically responded, ‘Yes.’

‘No, that’s not how money works,’ her dad insisted.

No matter if you practice ‘boy’ or ‘girl’ math, the phycological justification can help easy the pain most people are facing at the cash register.

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