COSvsReformation, Size Comparison
Reformation tends to run smaller than COS. If you wear a Medium at COS, you may need a Large at Reformation. For a measurement-based recommendation, use the fit checker.
COS vs Reformation sizing, quick answer
Reformation runs about one size smaller than COS. If you wear a Medium at COS, you'll likely need a Large at Reformation. For an exact recommendation, build a free fit profile.
- COS: runs large
- Reformation: runs small
- If between sizes: size up at the brand that runs smaller, or use the fit checker below for a personalised recommendation.
Brand guide
Compare how COS and Reformation usually fit, where cuts feel slimmer or roomier, and which categories are most predictable.
GENERAL BRAND GUIDANCE
This is a general brand-level sizing summary, not an exact product recommendation. For your specific size, paste a product link into the fit checker.
The Verdict
COS sizing compared to Reformation: COS runs large while Reformation runs small. Here is how the sizes translate.
Reformation tends to run smaller than COS. If you wear a Medium at COS, you may need a Large at Reformation. For a measurement-based recommendation, use the fit checker.
Category Match-up
Size Conversion Table
* Indicative only. For your personalised size at both brands,
Common Questions
Does COS run smaller than Reformation?
Reformation runs about one size smaller than COS. If you wear a Medium at COS, you'll likely need a Large at Reformation. For an exact recommendation, build a free fit profile.
Should I size up or down at COS vs Reformation?
Size up one at Reformation compared to COS. Reformation runs smaller, so if you wear a Medium at COS, try a Large at Reformation, especially for fitted tops and tailored bottoms.
If I'm a Medium at COS, what size am I at Reformation?
Since Reformation runs smaller than COS, a Medium at COS is roughly equivalent to a Large at Reformation. Use the ThisFits fit checker for a recommendation based on your measurements.
Does COS or Reformation fit differently by category?
Yes, fit varies meaningfully by category. Tops, Bottoms, Dresses can each fit differently than the brand's overall tendency suggests. See the Category Match-up section below for per-category guidance.
Which brand is more accurate to its size chart, COS or Reformation?
COS and Reformation both publish official size charts, but real-world fit varies by fabric, cut and category. The ThisFits engine cross-references published charts with shopper fit reports across 197+ brands to predict your size in each.
What if I'm between sizes at COS and Reformation?
If you're between sizes, Reformation tends to fit closer to the body, so trying the larger size first usually means fewer returns. Always confirm each retailer's return policy before ordering.