Column | Lewis: Girl math

My wife came home one day and said, “Honey, I have great news.”

“What’s that?” I asked, secretly hoping she was about to announce she wanted to take up golf.

“I just saved you $500,” she said with the pride of someone who had just completed a marathon.

Now I was interested, but suspicious. “How did you do that?”

“I went shopping today,” she said, “and there was a 50% off sale.”

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I paused for a moment, trying to decide whether to explain the flaw in this logic or simply survive the conversation. “Wow,” I said carefully. “That’s fantastic. Maybe we should celebrate this windfall and go out to dinner tonight.”

My daughter had been quietly watching this exchange. She looked at me and said two words:

“Girl math.”

“There’s actually a term for this?” I asked.

“Oh yes,” she said, smiling.

I checked later. She was right — it’s a real thing. Apparently, the internet has formalized an entire accounting system based on emotional satisfaction.

Now, before anyone accuses me of stereotypes, I did not create the meme. I was just genuinely curious. I wanted to understand the rules of this fascinating economic theory.

Apparently, the first rule of girl math is cost-per-use.

If you buy something expensive but use it often, it becomes cheap.

For example, if you buy a $300 pair of boots and wear them 100 times, they only cost $3 per use. And when you think about it, $3 is basically free. Which means if you don’t buy the boots, you are essentially losing money.

Then my daughter explained returns. If you return a $200 item, you didn’t just get your money back — you now have $200 available to spend. This is not a refund. This is a financial opportunity.

At this point, I began to suspect that I had been doing math incorrectly my entire life.

It gets better. If something is on sale, you didn’t spend money — you saved money. For example, if a jacket is 40% off and costs $120, you didn’t spend $120. You saved $80. The fact that your bank account is $120 lower is apparently just a minor accounting technicality.

There is also a timing rule. Purchases made late at night don’t really count because they happened in a different part of the day. And once the credit card statement closes, all previous purchases are emotionally reset to zero.

I called this calendar-based accounting, and it’s surprisingly effective.

Naturally, I tried applying traditional math to the system. I pointed out that if you spend $120, your net worth decreases by $120. My daughter looked at me the way you look at someone who insists on using a flip phone.

“That’s not how it works,” she said. And here’s the troubling part — she’s right. Not mathematically, but functionally.

Because I realized that I do this too. I have what I now call “garage math.” If I buy a new tool that saves time, then I’m actually saving money — because my time has value. If I buy a tool I might use someday, it’s an investment. And if I buy a tool I will definitely never use, it’s still fine because: seeing the envy on my friends’ faces when I show them the tool — priceless.

Then there’s vacation math. Once you’re on vacation, prices have a location filter. A $22 cocktail isn’t expensive if you’re near water. In fact, the closer you are to water, the less money matters. At some point you’re no longer paying for the drink — you’re paying for the sunset, the ocean breeze, and the comforting illusion that you deserve this.

There’s also subscription math, which is particularly dangerous. Anything under $10 a month is basically free. Which is how you end up with twelve things that are each “basically free” adding up to something that is very much not free.

But my personal favorite is comparison math. This is when you justify buying something stupidly expensive by comparing it to something more stupidly expensive that you didn’t buy. My wife used this method while choosing wallpaper for our new house. She would find wallpaper priced roughly like it was woven from $20 bills and say, “Oh, that one is high — but I found one that’s $2,000 cheaper.”

This is like saying, “The Rolls-Royce felt a little expensive, so I went with the Bentley.”

Girl math isn’t really about math — duh. It’s about storytelling and feeling good about buying stuff. Traditional math focuses on totals, balances, and consequences. It lacks imagination. Girl math, on the other hand, is optimistic. It finds value where none previously existed. It turns a purchase into a victory.

Is it accurate? No. Is it effective? Absolutely.

I have not fully converted. I still occasionally check my bank account, which is a habit I may need to break. But I have started experimenting.

For example, I recently avoided buying something for $200. Which means, according to my daughter’s math … I just made $200.

Honestly, I’ve never felt more financially secure.

Mark Lewis, a Colorado native, had a long career in technology, including serving as the CEO of several tech companies. He’s now retired and writes thriller novels. Mark and his wife, Lisa, and their two Australian Shepherds — Kismet and Cowboy, reside in Edwards.