Clothing sizes were never scientific measurements—they're marketing tools that have drifted over decades. A size 8 in one brand might fit like a size 12 in another, and even within the same brand, sizing shifts as target demographics change. Understanding why sizes are unreliable is the first step toward finding clothes that actually fit your body.
Why Sizing Inconsistency Exists
Sizing systems emerged from marketing, not anatomy. In the early 20th century, brands created size charts to standardize production, but they were based on limited body data and often skewed toward specific demographics. As fashion became more commercial, brands realized they could manipulate sizing to make customers feel better about their purchases.
Vanity sizing is the practice of labeling larger garments with smaller numbers. A brand might call a garment that measures 34 inches at the waist a 'size 8' instead of a 'size 12' to flatter shoppers. This isn't universal—some brands do the opposite (running small) to appeal to customers who want to feel they fit into smaller sizes. The result is complete chaos: there's no standard for what a size 8 actually means.
Brand drift compounds the problem. As companies chase different customer segments, their size blocks shift. A brand targeting younger customers might make sizes smaller and tighter; one targeting professionals might add more ease. Even within a single brand, sizing can change season to season as designers adjust patterns. The size label on a garment tells you almost nothing about whether it will fit your body.
Why Current Solutions Fail
Size charts are the most common attempt at solving this, but they're fundamentally flawed. Most charts compress complex three-dimensional bodies into a few measurements: bust, waist, hip. They ignore shoulder width, torso length, arm length, rise, and the countless other dimensions that affect fit. Even when you match the chart perfectly, the garment might not fit because the chart doesn't account for how fabric drapes, stretches, or behaves on your specific body shape.
Trying on multiple sizes in stores works, but it's time-consuming and frustrating. Online shopping makes this worse—you're forced to guess, often ordering two or three sizes and returning the ones that don't fit. This guessing game costs time, money, and creates waste. As we explore in Why Online Clothing Returns Are So High, returns are mostly fit failures.
Customer reviews help somewhat, but they're inconsistent. One person's 'runs small' might mean something different to you. Reviews can't capture the nuance of how a garment fits different body types, and they're often written by people who don't understand their own measurements or how to assess fit objectively.
A Better Approach: Body-First Sizing
Instead of starting with size labels and hoping they match your body, start with your actual measurements. Capture your body data once using consistent methods—we cover this in How to Measure Your Body (Most Guides Are Wrong)—then use that data to find garments that match your dimensions, not arbitrary size labels.
Modern technology makes this practical. AI body scanning can capture your body shape accurately using just a phone camera, creating a 3D model that captures dimensions size charts miss. This data can then be matched to garment specifications, showing you which pieces will actually fit your body, regardless of what the size label says.
Made-to-measure and bespoke approaches take this further. As we explain in Made-to-Measure vs Bespoke vs Custom, these methods start with your body and build garments to match, rather than trying to fit your body into pre-existing size categories. The result is clothing that fits properly because it was designed for your specific dimensions.
What This Means for You
Stop trusting size labels. A size 8 from one brand might be perfect while a size 8 from another doesn't fit at all. Focus on measurements instead: know your key dimensions (bust, waist, hip, shoulder width, torso length) and compare them to garment specifications when available.
When shopping online, look for brands that provide detailed measurements for each garment, not just generic size charts. Better yet, look for brands that use body scanning or made-to-measure approaches that start with your body data.
The future of sizing is moving away from arbitrary labels toward body-aware systems that match garments to actual measurements. Until that's universal, understanding why sizes don't exist helps you navigate the current chaos more effectively.
Frequently Asked Questions
Why do sizes vary so much between brands?
Brands use sizing as a marketing tool. Vanity sizing (labeling larger garments with smaller numbers) makes customers feel good about fitting into a 'smaller' size. Different brands target different demographics and adjust their sizing accordingly. There's no industry standard, so each brand creates its own size system.
Can I trust size charts?
Size charts are better than nothing, but they're limited. They compress complex 3D bodies into a few measurements and ignore critical dimensions like shoulder width, torso length, and how fabric behaves. Even when you match a chart perfectly, the garment might not fit because charts don't account for body shape variations.
What's the best way to find my size?
Start with your actual body measurements, not size labels. Measure yourself consistently (see our guide on how to measure your body), then compare those measurements to garment specifications. Better yet, use body scanning technology or made-to-measure services that start with your body data rather than trying to fit you into pre-existing size categories.
Will sizing ever be standardized?
Unlikely, because sizing serves marketing purposes beyond just fit. However, technology is moving toward body-aware systems that match garments to actual measurements rather than arbitrary labels. AI body scanning and made-to-measure approaches bypass size labels entirely by starting with your body data.
Why do my measurements match a size chart but the garment still doesn't fit?
Size charts only capture a few dimensions (typically bust, waist, hip) but ignore shoulder width, torso length, arm length, rise, and body shape variations. They also don't account for how different fabrics drape, stretch, or behave. Your body is three-dimensional and complex—a simple chart can't capture all the factors that affect fit.
Related Reading
How to Measure Your Body (Most Guides Are Wrong)
Practical, non-fussy steps to get repeatable measurements at home.
Made-to-Measure vs Bespoke vs Custom
Clear differences, when each makes sense, and why cost varies.
Why Online Clothing Returns Are So High
Fit uncertainty, cost to brands, and what better sizing looks like.