How to measure a shirt

Neck:
Measure a shirt collar that fits you well. Lay the collar flat. Measure from center of collar button to far end of opposite button hole. Or mesure around base of the neck (the lowest point of the neck). Number of inches equals the neck size you should order.

Sleave length:
With arm relaxed at side and slightly bent, measure from center back neck, over top of shoulder, down outside of arm to wrist.