How Clothing Sizes Work

There's no global authority that defines what "Medium" means. Here's why that gap exists — and how brands fill it.

Sizes are brand-specific patterns, not a universal standard

Each brand designs its own "block" — a base pattern for a given size — based on its own target body shape, market research, and design philosophy. There is no single international body that mandates exact measurements for "Medium" the way there is for, say, units of weight.

Body measurements vs garment measurements

A size chart's "chest 38-40 inches" usually refers to the wearer's body measurement, not the actual flat width of the garment — the garment itself is cut with extra room (called "ease") so it doesn't fit skin-tight.

Vanity sizing

Some brands, especially in women's fashion, have gradually adjusted their size labels smaller over the decades — a modern "size 8" often corresponds to what used to be labeled a larger size decades ago. This is a marketing-driven trend rather than a measurement one.

What this means for you

Treat any size chart — including ours — as a well-informed estimate, and prioritize a specific brand's own chart when you have access to it.