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Sizing for men's pants is generally easy. What's the size of your waist and how long are your legs? Underwear? Not so much. We're stuck in the rut with ill-defined sizes like "extra small" and "large". Enough of that. Here are the top underwear brands, and what measurements those S, M, and L tags actually line up to.

Waist (inches) 26 28 30 32 34 36 38 40
2(X)IST S S/M M M/L L L/XL XL
Agacio S S M M/L L XL XL
American Eagle XS XS/S S S/M M L L XL
Andrew Christian XS XS/S S/M M/L L/XL XL
AussieBum 2XS XS S M L XL 2XL 3XL
Big Boys S S M M L L XL
BN3TH 2XS XS S M L L/XL XL XL
C-IN2 XS S S/M M M/L L XL 2XL
Calvin Klein S S M M L L XL
Champion XS S S M M L L XL
Cocksox S S M M L L XL
Comfyballs S S/M M M/L L XL 2XL
David Archy S S M M L L XL
Duluth Trading Co S S M M L L XL
Ergowear XS XS/S S/M M/L L/XL XL
Fruit of the Loom S S M M L L XL
Hanes XS S S M M L L XL
Hung S S M M/L L L/XL XL
Jockey S S M M L L XL
Jockmail M M/L L/XL XL/2XL 2XL
Jack Adams S S M M/L L XL XL
Lapasa 2XS XS XS/S S M M/L L XL
Lululemon XS S M M/L L XL XL
Mack Weldon S S/M M M/L L/XL XL XL
MeUndies S S/M M M/L L XL XL/2XL 2XL
N2N XS S S/M M L L/XL XL
Nike XS XS S S M M
Obviously S S M M L L
Pair of Thieves S S/M M L L XL XL
Pump S S/M M/L L/XL XL
Reebok XS XS S S/M M/L L L/XL XL
Saxx XS S S/M M L L/XL XL
Separatec S S M M L L XL
Sheath S S M M L L XL
Shinesty S M L L XL XL
Sukrew S S/M M M/L L XL
T-Bô S S/M M L XL XL
UFM XS S S M M L L XL
Underarmour XS S M M L L XL XL
Unico S M L XL
Uniqlo S S S/M M M/L L/XL XL 2XL
WildmanT S S/M M L L/XL XL XL