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Wear

Why Activewear Sizing Is Still Broken

Small, medium and large tell us surprisingly little about the bodies wearing them.

Theo Marsh

Theo MarshJuly 15, 20267 min read

Interior of a minimal clothing boutique with garment racks
In This Story

Key Takeaways

  • There is no shared sizing standard across activewear brands, so size labels aren't comparable between them.
  • Fit is the leading driver of returns in the category, and stretch fabric only masks the problem up to a point.
  • Detailed brand-specific measurement charts remain the most reliable sizing reference available to shoppers today.

Every activewear brand claims to fit real bodies. Almost none of them size against the same body. A medium from one label can sit closer to a small or a large from another, and the label itself gives you no reliable way to know which until the package arrives.

The problem isn't laziness — it's fragmentation

There's no shared sizing standard across the activewear industry, and each brand's size chart is typically built from its own limited fit-model data, then adjusted based on returns and customer complaints over time. The result is a patchwork of internally consistent but mutually incompatible systems.

Estimated share of online activewear orders returned due to fit issues

~25–30%

Fit remains the single largest driver of returns in the category, ahead of style or quality complaints.

Stretch fabric hides the problem, briefly

Compression and stretch fabrics can paper over a lot of sizing inconsistency, which is part of why the category got away with loose standards for as long as it did. But stretch has limits, and the more technical a garment gets — compression tights, structured sports bras — the less forgiving that gap becomes.

Stretch is a forgiving fabric, not a substitute for an accurate size chart.

What's actually changing

A handful of newer brands have started publishing genuinely detailed measurement charts, body-scanning a wider range of fit models, and offering extended size ranges without the usual quality drop-off at the edges. It's a slow shift, and it's being driven less by altruism than by the sheer cost of return logistics — but the direction is real.

A group fitness class wearing activewear in a bright studio
Fit issues are most visible in structured pieces — sports bras, compression tights — worn during movement.

Until a shared standard emerges, if one ever does, the most useful thing a shopper can do is ignore the letter on the tag entirely and go straight to a brand's own measurement chart. It's not elegant, but it's currently the only reliable method available.

Frequently Asked

Why do the same size feel different across brands?

Each brand builds its own size chart from its own fit models and adjusts it independently over time. There's no shared industry standard, so 'medium' is really shorthand for that specific brand's internal sizing logic.

Is there a reliable way to size activewear online?

Measurement charts, rather than size labels, are the most reliable reference. Comparing your actual measurements to a brand's published chart avoids most of the inconsistency between labels.

Will activewear sizing ever become standardized across brands?

Unlikely in the near term. A handful of brands are improving their own charts and extended-size offerings, largely to cut return costs, but there's no active industry-wide push toward a shared standard the way there has been in some other apparel categories.

Sources

  • Apparel industry return-rate and fit-complaint data reported by e-commerce logistics providers

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