Sunspel vs Under Armour: which size fits the same?

In tees, a Sunspel L is closest to an Under Armour M (1¼″ roomier). In polos, a Sunspel L is closest to an Under Armour M (1″ roomier).

Tees

Under Armour tees measure about 4¾″ more around than Sunspel at the same size. A Sunspel L is closest to an Under Armour M (1¼″ roomier).

SunspelChest · lengthClosest Under ArmourChest · lengthUnder Armour is
Sunspel XS34¾″ · 26″none close
Sunspel S37″ · 26¾″none close
Sunspel M39½″ · 27″Under Armour S40″ · 28¾″½″ roomier
Sunspel L41¾″ · 27¾″Under Armour M43″ · 29¼″1¼″ roomier
Sunspel XL44″ · 28½″Under Armour M43″ · 29¼″1″ snugger
Sunspel XXL46¼″ · 29¼″Under Armour L46″ · 29¾″the same around
Sunspel 3XL48½″ · 30″Under Armour XL49″ · 30¾″½″ roomier

From Sunspel: Sunspel Classic T-Shirt. From Under Armour: Under Armour Team Tech Tee (1376842), Under Armour Athletic 2.0 Tee (1383264). Relaxed and oversized cuts are left out.

Polos

Under Armour polos measure about 4¼″ more around than Sunspel at the same size. A Sunspel L is closest to an Under Armour M (1″ roomier).

SunspelChest · lengthClosest Under ArmourChest · lengthUnder Armour is
Sunspel XS34¾″ · 25¾″none close
Sunspel S37″ · 26½″none close
Sunspel M39¾″ · 27¼″Under Armour S40½″ · 29″¾″ roomier
Sunspel L42½″ · 28″Under Armour M43½″ · 29½″1″ roomier
Sunspel XL45¼″ · 28¾″Under Armour L46½″ · 30″1¼″ roomier
Sunspel XXL47¾″ · 29½″Under Armour L46½″ · 30″1¼″ snugger
Sunspel 3XL50¼″ · 30¼″Under Armour XL49½″ · 31″¾″ snugger

From Sunspel: Sunspel Riviera Polo Shirt (Slim Fit). From Under Armour: Under Armour Tech Polo (1370399). Relaxed and oversized cuts are left out.

More: Sunspel sizing · Under Armour sizing

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Garment measurements: the shirt itself, chest all the way around and length from shoulder to hem, from each brand's own chart or wholesale spec sheet, checked November 2026. Shirts with half or more cotton are shown as they come out of a dryer (about 2% less around and 4% shorter). Brands change their cuts, so check the shop's chart before you buy.