1- Ask somebody to measure around the fullest part of your chest in relax chest mode.  

2- Compare your sleeve length as well, for the perfect look. (In case of a difference of more than 2 inches, go for a custom size or email us your body measurements). 

3- Take your exact body measurements with bare skin. 

Please select 4-5 inches bigger chest size than your Actual/Natural chest size for perfect fitting.