The shirts neck is Sport, it means its size goes according to the chest size.
Measure around the largest part of the chest and shoulder blades; keep your arms relaxed.
Measure from the base of the neck, along the shoulder, down your arm to the wrist, keeping your arm relaxed and bent slightly at the elbow.
Measure around the waist at the narrowest point.
Measure from the base of the crotch down inside of the leg to the desired pant length.