If your part number starts with RU:
ITEM SIZE CHEST WAIST JACKET/DRESS HEIGHT Inseam
Baby
  
newborn(0-9 months)
1-2 (6-12 months)
- - - - -
Toddler
2-4 (1-2 years old)
-
22-24"
-
35-39"
-
Children
Small (3-4 years old)
Medium (5-7 years old)
Large (8-10 years old)
-
-
-
25-26"
27-30"
31-34"
-
-
-
44-48"
50-54"
56-60"
-
-
-
Teen
Boys
Girls (dress size 2-6)
-
32-34"
-
22-24"
34-36"
2-6
-
-
-
-
Women
X-small
Small
Medium
Large
Plus Size/Full Cut
31-32"
33-35"
36-38"
38-40"
42-44"
22-24"
25-26"
27-30"
31-34"
35-38"
2-6
6-10
10-14
14-16
16-22
-
-
-
-
-
-
-
-
-
-
Men
Small
Medium
Large
X-large
Standard
Plus Size/Full Cut
36"
42"
46"
-
-
50"
26-28"
30-34"
36-40"
-
-
42-46"
34-36"
38-40"
42-44"
44-46"
up to 44"
46-52"
-
-
-
-
-
-
33"
33"
33"
33"
33"
33"
PET Costumes:
XSmall: 8"-10" from neck to tail base.
( Toy Poodle, Maltese, Shih Tzu)
Small: 11"-14" from neck to tail base.
( Cats, Yorkies, Pugs, Jack RuSell)
Medium: 15"-22" from neck to tail base,
( Beagles, Cocker Spaniels, Shelties)
Large: 22"-28 from neck to tail base,
( Labs, Boxers, Dobermans)
X Large: 28"+ from neck to tail base

Universal Women's Dress Size Conversion Chart
This is only a guide if the manufacture lists measurements in inches use that.

U.S. U.S. (letter sizes) U.K. France

Select the size in your country and note the US sizing.
Germany Italy Australia Japan