size Biceps Forearm 10cm above knee cap Calf
XS 18 - 22 16 - 20 33 - 37 27 - 30
S 23 - 27 21 - 25 38 - 41 31 - 34
M 28 - 32 26 - 30 42 - 45 35 - 38
L 33 - 37 31 - 35 46 - 49 39 - 42
XL 38 - 42 36 - 40 50 - 53 41 - 46

Measure the circumference of your arm [1] approx 10 cm / 3.9 inches above the center of your elbow bone. Measure the circumference of your thigh [2], taken 10 cm / 3.9 inches above the center of your knee cap.