When I first heard about the “girlmath” trend, I was fuming.

The popular TikTok meme is often used to justify frivolous spending and less-than-rational decision-making. These TikTok #girlmath videos proclaim that cash isn’t “real money.” Or that buying something on sale is saving money (even if you weren’t going to buy that item in the first place). [1]

“This is so annoying,” I angrily typed out to a couple of colleagues.

First, why do grown women call themselves girls? And it’s beyond infuriating to encounter the notion that women can’t do math or handle their finances responsibly.

But #girlmath is also supposed to be funny, so it’s not necessarily meant to be taken literally. And below the surface, could there be any merit to some of the ideas?

Here, I’ll dig into some of the most common beliefs often tagged with the #girlmath moniker and give my opinion on the principles behind each one.

If you buy something with cash, it doesn’t count as spending because cash isn’t real money.

This is obviously false. Cash is part of your net worth, and spending it depletes your bank account. However, if you give yourself a weekly budget for day-to-day expenses like coffee, gum, snacks, or after-work drinks, and make a practice of only paying for them in cash, this notion might be somewhat useful. If you stick to paying in cash and don’t turn to plastic the second you need it, it may be easier to abide by your budget than it is when you’re swiping your credit card.

As long as you do that, it’s OK to give yourself some freedom not to sweat spending for incidentals.

The verdict: Mostly wrong.

If you return an item that you’ve purchased, you get free money to spend.

I can see the logic with this one. When you purchase an item, you’ve already made the decision to spend, and the money has already disappeared from your wallet. When you get a refund after making a return, you do in a sense have more money available than you had previously planned.

As long as the original purchase decision fits within your budget, I don’t see anything wrong with spending the money you get back, assuming that buying things and returning them doesn’t devolve into out-of-control spending.

The verdict: Probably OK.

Spending $100 five times is better than making one purchase of $500.

I probably don’t need to explain why this thinking is flawed. And I suspect that many consumers (regardless of gender) fall into the trap of avoiding big-ticket purchases, just to end up buying multiple things that add up to the same amount.

Instead, it’s helpful to think of your spending holistically. And in many cases, buying one better-quality item that will last for many years is better than buying a bunch of cheap things that need to be replaced more often.

The verdict: Wrong.

When you spend on things like Botox, pricey fitness classes, or jewelry, you’re making an investment.

The thinking behind this one is that while the initial outlay for seemingly frivolous things may be steep, you ultimately get something in return—such as a better self-image, more confidence, or a family heirloom that will hold its value over time.

There is some merit to this idea. In my opinion, it’s helpful to think about the return on investment from things you buy. And there’s nothing inherently wrong with seemingly indulgent spending on luxury goods or services that help you meet a nonfinancial goal. Again, just make sure it fits within your budget and doesn’t lead to rationalizing overspending.

The verdict: Probably OK, up to a point.

Buying things on sale now to avoid a future cost gives you free money.

The idea behind this one is that you can justify an expense now if it helps you avoid spending a larger amount later. For example, buying a winter coat that happens to be on sale during the sweltering summer months.

This doesn’t really give you free money, but it does make sense financially. If you can buy something out-of-season at a deep discount, you’ll eventually be better off than if you waited to buy it at a higher price. Again, this assumes that you really were going to eventually buy the item anyway and aren’t only drawn to it because of the sale.

The verdict: Not exactly true, but not a bad practice.

Buying an expensive handbag or piece of clothing doesn’t really cost that much if the cost per wear is low.

You might balk at the price of a $500 tote bag, but if you carry it every weekday for a year, the costs works out to less than $2 per day, which seems a lot more palatable.

I agree that it makes sense to calculate this metric for big-ticket purchases. All else being equal, it’s better to spend up for items that you frequently use or expect to last many years than shelling out for an expensive blouse or purse that languishes in the back of the closet.

The problem: It’s not always easy to judge how much you’ll use something ahead of time. In the flush of excitement about a potential purchase, it’s easy to get swept away by an overly optimistic estimate about how much you’ll actually use it.

The verdict: Calculating cost per wear makes sense, but can be tricky to estimate.

Lessons Learned From #GirlMath

At the end of the day, the #girlmath meme reveals many of the behavioral pitfalls human beings—regardless of gender—can often be prone to. When it comes to financial decisions such as spending and investing, few of us manage to make rational choices 100% of the time.

But that’s not to say that the only way to be financially responsible is to sock away every possible dollar for retirement while obsessively budgeting every penny. Money is ultimately a means to an end, not an end in itself.

As The White Coat Investor’s Jim Dahle has written, you should spend your money on the things you value the most. There’s nothing wrong with spending on things you enjoy and value—even luxury items—as long as you’re still saving enough to meet your future goals.

[1] For the curious, here are some videos explaining these concepts.