Lululemon to Under Armour leggings size
The short answer
lululemon 4 is Under Armour XXS by the two brands' own charts.
Both brands publish the body waist each size is cut for, so every row matches a waist, not a tag.
| lululemon | lululemon builds it for | Under Armour, by chart | Same label | Under Armour builds it for | Under Armour also prints |
|---|---|---|---|---|---|
| 0 | waist 21 in, hip 32 in | not made | not published | not published | not published |
| 2 | waist 23 in, hip 33 in | not made | XXS | not published | not published |
| 4 | waist 25 in, hip 35 in | XXS | XS | waist 24.5 to 25.5 in, hip 33 to 34.5 in | US numeric 00 |
| 6 | waist 27 in, hip 37 in | XS | not published | waist 25.5 to 27 in, hip 34.5 to 36 in | US numeric 0-2 |
| 8 | waist 29 in, hip 39 in | SM | not published | waist 27 to 29 in, hip 36 to 38 in | US numeric 4-6 |
| 10 | waist 31 in, hip 41 in | MD | not published | waist 29 to 31 in, hip 38 to 40 in | US numeric 8-10 |
| 12 | waist 33 in, hip 43 in | LG | XL | waist 31 to 34 in, hip 40 to 43 in | US numeric 12-14 |
| 14 | waist 35 in, hip 45 in | XL | XXL | waist 34 to 37 in, hip 43 to 46 in | US numeric 16 |
| 16 | waist 38 in, hip 47 in | XXL | not published | waist 37 to 40 in, hip 46 to 49 in | US numeric 18 |
| 18 | waist 41 in, hip 49 in | 1X | not published | waist 39 to 43.5 in, hip 47 to 50.5 in | US numeric 16W-18W |
| 20 | waist 43 in, hip 51 in | 3XL | not published | waist 40 to 43 in, hip 49 to 52 in | US numeric 20 |
What wearers say
Charts describe a garment. People who own both brands describe a fit, and their answer ranks above this table once five of them stand behind it. Pick your size in the converter to see whether there are enough yet.
Sources
- lululemon size guide, read on 2026-09-17. lululemon on TrueToSize
- Under Armour size guide, read on 2026-09-17. Under Armour on TrueToSize