Nike vs Under Armour: which size fits the same?
In tees, a Nike L is closest to an Under Armour M (1¼″ snugger). In polos, a Nike L is closest to an Under Armour L (the same around).
Tees
Under Armour tees measure about 1″ more around than Nike at the same size. A Nike L is closest to an Under Armour M (1¼″ snugger).
| Nike | Chest · length | Closest Under Armour | Chest · length | Under Armour is |
|---|---|---|---|---|
| Nike XS | 33¼″ · 26″ | none close | ||
| Nike S | 37¾″ · 27½″ | none close | ||
| Nike M | 40½″ · 27½″ | Under Armour S | 40″ · 28¾″ | ½″ snugger |
| Nike L | 44¼″ · 28¾″ | Under Armour M | 43″ · 29¼″ | 1¼″ snugger |
| Nike XL | 48¼″ · 29½″ | Under Armour XL | 49″ · 30¾″ | ¾″ roomier |
| Nike XXL | 52″ · 30¼″ | Under Armour XXL | 52″ · 31¾″ | the same around |
| Nike 3XL | 56″ · 31″ | Under Armour 3XL | 55″ · 32¾″ | 1″ snugger |
From Nike: Nike Team rLegend Tee, Nike Legend Tee, Nike Core Cotton Tee. From Under Armour: Under Armour Team Tech Tee (1376842), Under Armour Athletic 2.0 Tee (1383264). Relaxed and oversized cuts are left out.
Polos
Nike polos measure about 1″ more around than Under Armour at the same size. A Nike L is closest to an Under Armour L (the same around).
| Nike | Chest · length | Closest Under Armour | Chest · length | Under Armour is |
|---|---|---|---|---|
| Nike XS | 37″ · 28¾″ | none close | ||
| Nike S | 40¼″ · 29¼″ | Under Armour S | 40½″ · 29″ | the same around |
| Nike M | 43¼″ · 29½″ | Under Armour M | 43½″ · 29½″ | the same around |
| Nike L | 46½″ · 30¼″ | Under Armour L | 46½″ · 30″ | the same around |
| Nike XL | 50½″ · 31½″ | Under Armour XL | 49½″ · 31″ | 1″ snugger |
| Nike XXL | 54½″ · 32¾″ | Under Armour 3XL | 55½″ · 33″ | 1″ roomier |
| Nike 3XL | 58¼″ · 34″ | none close |
From Nike: Nike Dri-FIT Micro Pique 2.0 Polo, Nike Dri-FIT Victory Solid Polo, Nike Dri-FIT Legacy Polo, Nike Dri-FIT Vertical Mesh Polo, Nike Dry Essential Solid Polo. From Under Armour: Under Armour Tech Polo (1370399). Relaxed and oversized cuts are left out.
More: Nike sizing · Under Armour sizing
Get your exact size in any of these
Add three shirts you own that fit well. FitCard compares their real measurements with every shirt here and tells you the one size to buy, and why, in terms of your own shirts. Free, no tape measure.
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.