Brand Comparison · 2026

    PatagoniavsUnder Armour, Size Comparison

    Under Armour tends to run smaller than Patagonia. If you wear a Medium at Patagonia, you may need a Large at Under Armour. For a measurement-based recommendation, use the fit checker.

    Quick Answer

    Patagonia vs Under Armour sizing, quick answer

    Under Armour runs about one size smaller than Patagonia. If you wear a Medium at Patagonia, you'll likely need a Large at Under Armour. For an exact recommendation, build a free fit profile.

    • Patagonia: runs large
    • Under Armour: 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 Patagonia and Under Armour 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

    Patagonia sizing compared to Under Armour: Patagonia runs large while Under Armour runs small. Here is how the sizes translate.

    Under Armour tends to run smaller than Patagonia. If you wear a Medium at Patagonia, you may need a Large at Under Armour. For a measurement-based recommendation, use the fit checker.

    PatagoniaRUNS LARGE
    Under ArmourRUNS SMALL
    Patagonia logo

    Patagonia

    RUNS LARGE

    Outdoor heritage, runs large with relaxed fits

    Under Armour logo

    Under Armour

    RUNS SMALL

    Under Armour runs small, size up 0.5 in most categories

    Category Match-up

    Patagonia
    Under Armour
    Tops
    RUNS LARGE

    Flannel shirts and tees run large with a relaxed fit. Size down for a more fitted look.

    RUNS SMALL

    Compression and HeatGear tops run very small. Loose-fit styles are closer to true to size. Size up 1 for a relaxed fit.

    Bottoms
    RUNS LARGE

    Pants run large through the seat and thigh. Size down 1 for a standard fit.

    RUNS SMALL

    Athletic shorts and joggers run small in the waist. Size up 1. Storm pants are slightly more generous.

    Outerwear
    RUNS LARGE

    Fleeces and jackets run large. Size down 1 for a trim fit, or stay true for layering.

    RUNS SMALL

    Storm and ColdGear jackets run small through the chest and arms. Size up 1 for layering room.

    Size Conversion Table

    Your SizePatagoniaUnder Armour
    XXS<XXS(Runs Large)XS(Runs Small)
    XSXXS(Runs Large)S(Runs Small)
    SXS(Runs Large)M(Runs Small)
    MS(Runs Large)L(Runs Small)
    LM(Runs Large)XL(Runs Small)
    XLL(Runs Large)XXL(Runs Small)
    XXLXL(Runs Large)XXXL(Runs Small)
    XXXLXXL(Runs Large)XXXL+(Runs Small)

    * Indicative only. For your personalised size at both brands,

    Common Questions

    Does Patagonia run smaller than Under Armour?

    Under Armour runs about one size smaller than Patagonia. If you wear a Medium at Patagonia, you'll likely need a Large at Under Armour. For an exact recommendation, build a free fit profile.

    Should I size up or down at Patagonia vs Under Armour?

    Size up one at Under Armour compared to Patagonia. Under Armour runs smaller, so if you wear a Medium at Patagonia, try a Large at Under Armour, especially for fitted tops and tailored bottoms.

    If I'm a Medium at Patagonia, what size am I at Under Armour?

    Since Under Armour runs smaller than Patagonia, a Medium at Patagonia is roughly equivalent to a Large at Under Armour. Use the ThisFits fit checker for a recommendation based on your measurements.

    Does Patagonia or Under Armour fit differently by category?

    Yes, fit varies meaningfully by category. Tops, Bottoms, Outerwear 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, Patagonia or Under Armour?

    Patagonia and Under Armour 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 Patagonia and Under Armour?

    If you're between sizes, Under Armour 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.

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    Your Personal Size

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