This is only a guideline, and please note the measurements below are the measurements of the garment.

Adult

Small - 34in - 36in (92cm) chest. 32" waist
Medium - 38in - 40in (100cm) chest. 34" waist
Large - 42in - 44in (108cm) chest. 36" waist
X Large - 46in - 48in (116cm) chest. 38" Waist
XX Large - 50 in - 52 in (124cm) chest. 40" waist
XXX Large - 52in - 54 in (132cm) chest. 42" Waist

Women

8 UK (38 continental), (6 US)
10 UK (40 continental), (8 US)
12 UK (42 continental), (10 US)
14 UK (44 continental),(12 US)
16 UK (46 continental),(14 US)
18 UK ( 48 continental)(18 US)

Children

SB - 5/6yrs 24in - 26in Chest. 24" Waist
MB - 7/8 yrs 26in - 28in Chest. 26" Waist
LB - 9/10 yrs 30in - 32in Chest 28" Waist
YTH - 11/12 yrs 32in - 34in Chest. 30" waist.