Use the chart below to determine the best size for you. The adult uniforms are based on 3 factors...
Mens Clothing Size: X-Small, Small, Medium, Large, X-Large, 2X-Large
Chest Size: This is normally the sport coat size on a male and chest size on a female
Height: The two options to choose are REGULAR(shorter than 5'11") or LONG(taller than 5'11"). If you are 5'11", I recommend going with LONG to be safe.