Order your normal size. Both fits run true, not oversized streetwear and not gym-tight, but Performance and Heavyweight are cut from two different patterns, so the same letter means slightly different numbers depending on which one you're buying.
TWO SHIRTS, TWO PATTERNS
The Performance tee is cut from lightweight polyester built to move with you through Muay Thai and conditioning work, so the pattern sits slightly closer to the body. The Heavyweight tee (used for Balance and Here To Make History) is a denser, high-GSM cotton, and it's cut with a bit more room to match the fabric's weight. Both are measured the same way: chest width flat across, and body length from shoulder to hem.
PERFORMANCE TEE
| Size | Chest width | Body length |
|---|---|---|
| M | 51 cm | 68 cm |
| L | 54.5–55 cm | 71.5–72 cm |
| XL | 56.5 cm | 74 cm |
HEAVYWEIGHT TEE
| Size | Chest width | Body length |
|---|---|---|
| M | 52 cm | 68 cm |
| L | 56 cm | 75 cm |
| XL | 57 cm | 79 cm |
HOW TO MEASURE YOURSELF
Lay a shirt that already fits you the way you want flat on a table. Chest width is the distance straight across from armpit to armpit, doubled if you're comparing to a tag that only lists half. Body length is from the top of the shoulder seam straight down to the hem. Match those two numbers to the closest size above rather than guessing off a size chart alone, chest and length don't always scale together the same way across brands.
ONE THING TO KNOW
Size S sells out first on almost every drop, usually within the first week. If you're on the edge between S and M, don't wait on it. Check current stock on the product page before it's gone again.