'To Fit' (Chest/Inches):
Age 6: 23-24"
Age 8: 25-27"
Age 10: 27-29"
Age 12: 30-32"
Age 14: 33-35"
SM: 36-38"
MED: 39-41"
This Garment is 'very fitted' and comes up small for the size description.
If you prefer a looser fit consider a size up from your normal size.