WHY CLOTHING SIZES MAKE NO SENSE: THE ECONOMICS BEHIND MODERN SIZING

I know you can relate to this.

You wear a size 8 at one brand, a size 4 at another, and a size 12 somewhere else. Ordering online becomes a postal nightmare. Dressing rooms feel like endurance sports if you don’t drag the entire size run in with you. And tell me I’m not the only one who has walked away from a perfectly good piece simply because I didn’t want to get dressed, go find another size, undress again, and repeat the whole exhausting dance.

It’s hard not to internalize it. Hard not to feel like there must be something wrong with your body.  Logically, though, we know that’s not true. This isn’t because women’s bodies are chaotic, and it’s not because the industry is entirely incompetent. Well. Maybe it is, a little.

Mostly, it’s because clothing sizes are not a universal measurement system. They are brand-specific labeling systems shaped by economics, positioning, and production realities.  Having worked on the design side, I can tell you: sizing isn’t random.

Let’s pull back the curtain.

FIRST, THERE IS NO UNIVERSAL SIZING AUTHORITY

In the United States, women’s sizing is not legally standardized.  There were attempts at standardization in the mid-20th century. But as ready-to-wear expanded and brands began competing more aggressively, uniform sizing became less useful than differentiation. I know that sounds frustrating. But standardization limits flexibility, and flexibility fuels competition. Brands need to target specific body distributions.  They need to align with a core customer, and they need to position themselves distinctly in the market. A universal system makes that harder, but instead of one truth, we have many internal ones.

Coming from a design background, I can’t realistically imagine or support universal sizing ever being adopted, even though I understand the appeal. Requiring every brand to adhere to the same rigid template would mean asking them to design for an abstract “average” customer who doesn’t actually exist. Fashion brands are built around specific bodies, proportions, and aesthetics. A universal system would simplify the numbers, but it would also flatten the nuance.

SIZING HAS DRIFTED FOR DECADES

If you’ve ever seen a professional dress form, you may have noticed the year is often stamped on it.  That’s not decorative.  It’s there because a size 8 in 1965 is not the same as a size 8 in 1995, and neither is the same as today. I went hunting for a photo I took of a dress form from the 60s, used for display at a small boutique that was a size 12. If the size wasn’t stamped on the dress form, any one of us would think it was actually a size 8.

Sizing has changed over the years because manufacturers and pattern companies have repeatedly revised size charts over the decades as body data shifted, markets expanded, competitive pressures intensified, and vanity sizing accelerated.  Even the forms had to evolve. A vintage size 12 pattern from the 1950s corresponds roughly to what many brands would label a size 6 or 8 today, which brings us to one of fashion’s favorite myths.

THE MARILYN MONROE “SIZE 14” CONVERSATION

You’ll often hear someone say, “Marilyn Monroe was a size 14.”  Yes. For her time, she was.  But in the 1950s, the smallest widely available ready-to-wear size for women typically started at a size 6. The numeric system began higher and ran differently than it does today. A 1950s size 14 does not translate to a modern size 14.

When people use that comparison now, they’re applying today’s sizing framework to a historical one. It’s like comparing currency across eras without adjusting for inflation.  The number stayed the same.  The system didn’t.

THE APPAREL EQUIVALENT OF A SHOE LAST

In footwear, every shoe begins with a last, a three-dimensional form that defines the shape and volume of a shoe. Change the last, and you change the entire fit. This last is the origin fit of all their shoes. Apparel works similarly, though less visibly.

A brand selects a base size, usually a 6 or 8, and a fit model whose proportions represent their target customer. The garment is refined on that person until it fits exactly the way the brand wants it to. That approved sample becomes the pattern block, just like a last becomes the last becomes the mold for shoes

What’s important to understand is that this base block isn’t engineered around some neutral, universal “average” body. It’s engineered around a specific person,  the fit model, whose proportions reflect the brand’s target customer. If that fit model is long-waisted and narrow-hipped, the entire sizing architecture will carry those assumptions. If she’s shorter-waisted with a fuller hip, that becomes the blueprint instead. These fit models are so famously well-known in the industry that a designer can call a dress form company and ask for a “Mary Smith” form, and the company will have her measurements on file. Fit models have a full dance card and work with many. brands.

Beyond the base size, every other size is graded up or down from there. Grading means taking the base block and adding or subtracting measurements at specific points, like bust, waist, hip, shoulder, length, etc., according to a set formula, and that formula varies by brand. Beyond the sample size, the measurements become very mathematical. Bodies, however, are not.

When you scale a garment evenly in circumference, you don’t automatically account for differences in torso length, bust distribution, hip shape, or thigh proportion.  To engineer distinct proportional blocks for every size range would require additional fit models, more development rounds, more sampling, more time, and significantly more cost. This is why some brands consistently fit you and others never will.

Most brands won’t absorb that unless precision fit is central to their identity. You may see this more often in the plus-size market, where proportional shifts require more specialized fitting and additional base blocks. This is also why missy brands can’t simply extend their sizing upward into plus-sizing because in this case, it’s not just about adding inches, it’s about redesigning the architecture, which missy brands are not set up to do.

And here’s the part that matters psychologically: when a shoe brand doesn’t fit, women rarely take it personally. We shrug and say, “That brand doesn’t work for me.”  But when a clothing brand doesn’t fit, we question our bodies. After more than two decades working with women, I can tell you that the moment something feels outside a woman’s control, the shape of her hips, the size of her thighs, the distribution of her weight — she is far more likely to internalize the mismatch and blame herself and not the clothing. But clothing not fitting your body is no different than shoes not fitting your foot.  It’s not your body that is wrong for the clothing, it’s the clothing that is wrong for your body.

If a brand doesn’t fit, take the pressure off yourself.  It has nothing to do with you.  It’s just not a fit.  Literally.

VANITY SIZING IS MARKET COMPETITION, NOT ACCIDENT

Vanity sizing gets talked about like it’s a scandal. It’s not. It’s competitive behavior.

When one brand adjusts its size chart downward and customers feel better fitting into a smaller number, sales increase. Studies have shown that when women perceive themselves as wearing a smaller size, they buy more. When sales increase, competitors respond. And this is where it becomes less of a decision and more of an arms race.

If Brand A quietly shifts its size 8 to measure closer to what used to be a 10, and customers feel good about it, Brand B can either hold its ground and risk looking “smaller” on the rack or adjust. Most adjust. Over time, the numbers drift.

I’m not saying vanity sizing was a brilliant long-term idea. We now have XXS and double zero because once you put smaller tags on larger garments, the smaller garments need new labels. The scale keeps stretching in both directions. It’s why the size 14 of today is not the size 14 Marilyn wore. It’s why I am technically the same size I was in high school, but in 1992 I wore an 8 and today I wear a 4.

And here’s the uncomfortable truth: once vanity sizing becomes normalized, it’s almost impossible to reverse. No brand wants to be the one that suddenly tells its customers they’ve “gained” two sizes overnight, even if nothing about their bodies has changed.So the numbers stay inflated. Or deflated, depending on how you look at it. I don’t care how rational or accomplished a woman is, I’ve seen it first-hand, numbers affect us. Even when we know they’re arbitrary.

Numbers are psychological.
Psychology drives purchasing.
Purchasing drives revenue.

GLOBAL MANUFACTURING ADDS VARIABILITY

Today’s garments are produced across global supply chains. A single brand might design in New York, develop patterns in Los Angeles, sample in one country, and produce bulk orders in another. That alone introduces variables.

Factories work within acceptable measurement tolerances — often a half inch to an inch, depending on the garment and the specific point of measurement. Clothing is still sewn by humans, and tolerance is built into the specification.

A quarter inch doesn’t sound like much. But multiply small tolerances across multiple seams — shoulder, side seam, sleeve cap, waistband — and you can meaningfully shift how a garment feels on the body. A slightly deeper armhole, a marginally longer rise, a hip that’s just a touch narrower than spec — these aren’t catastrophic errors. They’re within range. But they change the experience of wearing the piece.

Then there’s fabric.

A woven with no stretch behaves very differently from a stretch twill. If a brand doesn’t create separate patterns or make thoughtful adjustments for different fabric types, you will absolutely see variance in how those garments fit, even when they carry the same size label.

And then there’s the cutting room floor.

In mass production, fabric isn’t cut one piece at a time. It’s layered in stacks, sometimes dozens of layers high, and cut through all at once using industrial cutting machines. It’s efficient, which is the point. Cutting each garment individually would slow manufacturing to a crawl.

But when you cut through a large stack of fabric, small shifts can happen. The weight of the layers, the pressure of the blade, even slight movement in the lay can create subtle differences between pieces at the top and pieces at the bottom. There’s an old industry phrase: “top of the cut pile, bottom of the cut pile.” It’s not dramatic. It’s not sloppy manufacturing.  It’s physics.

Cut through a thick stack of paper and the bottom sheets won’t be perfectly identical to the top. Fabric behaves the same way. None of this means your garment is defective. It means it was produced in a system optimized for scale. The stricter a brand is about enforcing tolerances, the slower production becomes, the higher the cost, and the greater the oversight required. Every additional fitting, inspection, and correction adds time and money. In a fast-fashion world driven by speed, scale, and price sensitivity, precision rarely wins.  That doesn’t mean brands don’t care. It means they’re balancing cost, timeline, and consistency in a system that was never built for surgical accuracy.

E-COMMERCE CHANGED THE EQUATION

Online retail altered incentives in a way most consumers never see.

In a traditional brick-and-mortar model, fit had to work well enough that you kept the garment. Returns were inconvenient. Inventory lived in one place. If something didn’t fit properly, you might try another size, but you were unlikely to order three versions of the same dress and send two back. E-commerce changed that behavior entirely.

Today, many brands assume customers will order multiple sizes and return what doesn’t work. In fact, some quietly design their policies around it. Free returns remove friction. Easy shipping labels normalize experimentation. “Buy two, keep one” has become standard practice. From a business standpoint, this shifts the cost calculation.

Improving fit across an entire size range requires:

• Additional fit models
• More sampling
• More pattern revisions
• Slower production timelines
• Higher development costs

Absorbing a percentage of returns, by contrast, becomes a line item.

If the margin on a garment is strong enough, and if return rates stay within predictable thresholds, it can be more cost-effective to tolerate returns than to completely overhaul a sizing system. That sounds counterintuitive.  But it’s math.

Brands model expected return rates. They factor reverse logistics into pricing. They negotiate shipping rates at scale. They resell returned merchandise, discount it, or fold it into inventory planning. None of this is emotional.  It’s economic modeling.

Once returns are normalized, something subtle happens: precision fit becomes less urgent. If customers are already planning to order two sizes, the pressure to get it perfect on the first try diminishes. That doesn’t mean brands don’t care about fit. It means the incentive structure has shifted.  In a world where convenience drives conversion, ease of return can outperform perfection of fit.

SO IS SIZING BROKEN?

Not exactly.  Sizing works precisely the way a competitive global apparel market designed it to work.

Sizing is optimized for brand positioning, psychological comfort, margin protection, speed to market, and supply chain flexibility. It adapts to shifting body data, responds to consumer psychology, absorbs manufacturing variability, and competes aggressively for loyalty.  It is a marketing, production, and a retail system. What it is not, and has never truly been, is a scientific measurement system calibrated to your individual body. That distinction matters.

When we treat sizing as though it were biometric truth, we set ourselves up for unnecessary frustration. We assume the number is fixed, stable, and authoritative. But in reality, it’s fluid, contextual, and competitive.  Sizing was never engineered to be universal. It was engineered to function inside a fast-moving marketplace.  And once you see that, the inconsistency feels less like chaos and more like a consequence.

For sure, it doesn’t mean the system is perfect or couldn’t be improved. But it does mean the friction you experience in a dressing room or while ordering online isn’t a referendum on your body.  It’s the predictable outcome of a system built for scale, not precision.

THE MOST IMPORTANT TAKEAWAY

I could easily sugarcoat this and say, “The number inside your jacket is not a measurement of your body’s worth.” But that would feel about as hollow as when someone insists that age is just a number. Technically true. Emotionally irrelevant.

I can logic the heck out of this entire conversation and explain grading, tolerances, vanity sizing, supply chains, competitive positioning, and we would still feel a flicker of victory when we shimmy into a pair of pants one size smaller.  Yet, a woman’s relationship with her size is not rational. It never has been.  It is layered with decades of messaging about thinness and virtue, cultural expectations about desirability, the quiet hum of comparison, the legacy of body dysmorphia, the economics of beauty, and yes, patriarchy.  It is far deeper and richer and far more complicated than a spec sheet.

This is exactly why understanding how the system works matters.  Because when you know that the numbers are flexible, competitive, historically fluid, and economically motivated, you don’t have to pretend they mean nothing.  You just stop letting them mean everything.