Men's Size Guide:
  UK S M L XL
Neck Inches 14.5 15.5 16.5 17.5
Cm 37 39-41.5 42-44.5 45-47.5
Chest Inches 36 - 38.5 39 - 41 42 - 44 45 - 47
Cm 91 - 98 99 - 106 107 - 113 114 - 121
Waist Inches 29-31.5 32-34.5 35-37.5 38-40.5
Cm 73 - 80 81 - 88  89- 96 97 - 103
Sleeve Inches 33 34 35 36
Cm 84 86.5 89 91.5
Inseam Inches 30.5 31 32 32.5
Cm 77.5 79 81 82.5

Sizing refers to body measurements, not garment dimensions.

How to measure:
Neck: Around the fullest part of the neck, at the base                           
Chest: Around the chest, just under the arms and across the shoulder blades
Sleeve: From the centre back of the neck, across the shoulder, and down the arm to the wrist
Waist: Around the narrowest part of the waist
Hip: Around the widest point of the hips
Inseam: From the crotch to the anklebone on the inside of the leg

 

Size Torso Waist
S/M 41-48 cm 16-19 in 66-102 cm 26-40 in
M/L 47-55 cm 18.5-21.5 in 71-114 cm 28-45 in
One Size >41 cm >16 in 66-114 cm 26-45 in
Unisex Small 40-47 cm 15.5-18.5 in 69-81 cm 27-32 in
Unisex Medium 45-52 cm 17.5-20.5 in 73-86 cm 29-34 in
Unisex Large 50-57 cm 19.5-23.5 in 86-99 cm 34-39 in
Men's Medium 45-52 cm 17.5-20.5 in 73-86 cm 29-34 in
Men's Large 50-57 cm 19.5-23.5 in 86-99 cm 34-39 in
Women's Small 40-47 cm 15.5-18.5 in 76-89 cm 30-35 in
Women's Medium 45-52 cm 17.5-20.5 in 86-99 cm 34-39 in

For more information on how to fit your pack follow this link:  How Do I Fit My Pack?