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Girl Math, Boy Math, and the Psychology of Spending

Miriam Grosman Student Contributor, University of Virginia
This article is written by a student writer from the Her Campus at UVA chapter and does not reflect the views of Her Campus.

Why does spending $200 feel like a steal when it’s on sale, but $10 for parking feels like robbery?

Welcome to the world of girl math, boy math, and the very human psychology behind how we justify our spending. 

The Psychology between girl math and boy math

“Girl Math” started as a social media trend where people would justify purchases with creative logic. One example is, ‘It’s basically free if it’s on sale,’ or ‘Cash doesn’t count because it’s not real money.’

I have been a victim of this frame of thinking, but the truth is, “girl math” has nothing to do with being a girl. This ideology is just a form of the mental gymnastics we do to justify our spending habits. It’s a form of humor that makes money talk less intimidating and more human.

“Boy Math” is similar. It rationalizes that getting a $2,000 gaming setup is actually ‘saving money’ because they could be going out instead. Both girl and boy math highlights a human tendency to justify emotional spending with logic. It’s amusing until you see that both sides are simply articulating how different individuals value identities, experiences, and pastimes.

why our brains justify spending

To get away from social media terms and get down into real psychology, there are a few factors that make our brains think this way.

One of them is mental accounting, which gets into the idea that we put money in mental categories in our brains.

A $200 sherpa jacket might feel more worthwhile when you think about how much you’ll wear it, others’ perception of you, and the brand name. $10 parking feels like a waste because you don’t get much value outside of having a place to put your car.

We are more willing to spend, as a society, on items that boost our happiness than on actual needs. It is a growing trend in our generation, especially with the booming of advertising on platforms like TikTok.

pain of paying

With all of this also comes the idea of the “pain of paying.” We would rather spend money on fun, emotional purchases than on small, boring ones. These necessities trigger us to be more stingy with how much we are willing to spend. 

how brands use psychology against (and for) us

Brands have mastered getting in tune with the way consumers think.

One way they do this is through sales and discounts. Even just reading these words has probably set off an alarm in your brain. Discounts activate the reward centers in our brain. We feel like we’ve “won,” even if we spent more overall. The same goes for the anchoring effect, where seeing “$400 marked down to $200” makes $200 feel cheap, even if you never planned to spend that much.

We’re all doing this subconscious math every day, but the TikTok trend just makes it visible. These rationalizations help us reduce guilt and maintain a sense of control. Sometimes it even makes us budget subconsciously, such as when we use cost-per-wear or strategically use sales. On the other hand, it might also lead us to overspend. So the next time $200 feels like a bargain and $10 feels like a scam: don’t worry! It’s not bad math. It’s just being human.

Miriam Grosman is an undergraduate student at the University of Virginia, where she is pursuing a degree in Financial Mathematics. Her academic interests lie at the intersection of quantitative analysis and real-world financial applications, but her passion for writing has remained a consistent thread throughout her education. She was an active contributor to her high school newspaper, where she developed a strong interest in exploring media, culture, and the evolving role of women in the business world. At UVA, she continues to seek out opportunities to write about these topics, with a particular focus on how culture and commerce intersect in today’s global economy.

Originally from Fairfield, Connecticut, Miriam brings a New England perspective to her work and enjoys incorporating both regional and national viewpoints in her writing. Her journalistic style is informed by a keen eye for detail, an analytical mindset, and a commitment to amplifying underrepresented voices. She is especially passionate about highlighting the contributions of women in finance and business leadership. She believes in the power of storytelling to inform, inspire, and spark meaningful conversation.

In addition to her academic and writing pursuits, Miriam is also an accomplished musician. She plays the alto saxophone and has performed in various school ensembles over the years. When she is not studying or writing, she enjoys running, listening to classic rock, and discovering small coffee shops. She hopes to continue blending her interests in finance, media, and music into a career that bridges creativity with critical thinking.