Young women are trending on TikTok for sharing the head-scratching ways they justify their frivolous money-spending — all in the name of #GirlMath. 

In videos under the hashtag — which has exploded on the platform over the past week — girls explain how they legitimize what might otherwise be considered unsound purchases.

“If I paid for it with cash, it was free – it doesn’t count. Nothing came out of my account, [so] that was free money,” TikToker Sarah LeMoine said in an Aug. 4 video titled “GIrl Math.”

“If I make a bunch of small, little purchases that add up to $500 in a day, that’s not actually $500. But if one or two items itself is $500, why would I buy it? That’s actually $500,” she continued. 

Although LeMoine’s math “isn’t math-ing,” as Gen-Zers would say, her TikTok has amassed more than 1.7 million views and 325,000 “likes.’

And the Girl Math gets even fuzzier.

“Anything under $5 feels like it’s pretty much free. Girl Math,” Samantha James, 28, declared in an Aug. 3 TikTok using the hashtag.

Even a concert is “free,” James contends, if the tickets were bought far enough ahead.

“It’s just so funny that we all have this weird, psychological justification happening,” James said about herself and the other TikTokers engaging in #GirlMath, a trend which she calls “relatable.” 

“It’s just a good, positive mindset shift,” she continued. 

But financial experts aren’t buying it. 

“While there are definitely some pieces of sound financial advice to be found on TikTok, this ‘Girl Math’ trend definitely isn’t one of them,” said Jacob Channel, a senior economist at LendingTree.com.

“If you convince yourself that something you paid for is free when it isn’t, then you can quickly end up overspending and seriously hurting your finances,” Channel said. 

If one spends $5 on something frivolous every day, they’ll end up spending an extra $1,825 a year, the economist noted.

But James said the #GirlMath trend “is not about math as a science – it’s just supposed to be fun, light-hearted logic.

“It makes us feel better, so why not?” she said.