Below is a General Sizing Guide.
If your Measurements Fall Between Sizes, Please Order the Larger Size.
Because the manufactures only listed sizes in chart above, here are some gender sizing specs.

All Measurements in Inches with Item Laid Flat

Adult & Men's Shirts 
                 S         M         L         XL        2XL       3XL       4XL       5XL
Chest     34-36   38-40   42-44   46-48    50-52    54-56    58-60   62-64
Width       18        20        22        24        26         28         30       32
Length   27-29   29-30   30-31    31-32    32-33      33         34       35

Women's Shirts
               XS          S           M           L           XL           2XL
Size        4-6         6-8      10-12     12-14    14-16       16-18
Width       18          20         22         24         26            28
Length     26          27         28          29         30            31

Kids's Shirts
              XS           S          M            L           XL
Size       2-4         6-8      10-12      14-16     18-20
Width     16           17        18           19          20
Length  20.5          22       23.5         25         26.5