AritziavsCOS, Size Comparison
Aritzia tends to run smaller than COS. If you wear a Medium at COS, you may need a Large at Aritzia. For a measurement-based recommendation, use the fit checker.
Aritzia vs COS sizing, quick answer
Aritzia runs about one size smaller than COS. If you wear a Medium at COS, you'll likely need a Large at Aritzia. For an exact recommendation, build a free fit profile.
- Aritzia: runs small
- COS: runs large
- 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 Aritzia and COS 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
Aritzia sizing compared to COS: Aritzia runs small while COS runs large. Here is how the sizes translate.
Aritzia tends to run smaller than COS. If you wear a Medium at COS, you may need a Large at Aritzia. 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 Aritzia run smaller than COS?
Aritzia runs about one size smaller than COS. If you wear a Medium at COS, you'll likely need a Large at Aritzia. For an exact recommendation, build a free fit profile.
Should I size up or down at Aritzia vs COS?
Size up one at Aritzia compared to COS. Aritzia runs smaller, so if you wear a Medium at COS, try a Large at Aritzia, especially for fitted tops and tailored bottoms.
If I'm a Medium at Aritzia, what size am I at COS?
Since Aritzia runs smaller than COS, a Medium at Aritzia is roughly equivalent to a Small at COS. Use the ThisFits fit checker for a recommendation based on your measurements.
Does Aritzia or COS fit differently by category?
Yes, fit varies meaningfully by category. Tops, Outerwear, Bottoms 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, Aritzia or COS?
Aritzia and COS 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 Aritzia and COS?
If you're between sizes, Aritzia 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.