Small:

• around the neck of the dog (red color on the picture):
  11-20 inch (27-50cm)
• around the chest behind the front legs (green color on the picture):
  20-31 inch (50-80 cm)

Medium:

• around the neck of the dog (red color on the picture):
  13-23 inch (33-58cm)
• around the chest behind the front legs (green color on the picture):
  28-37 inch (70-94 cm)

Large:

• around the neck of the dog (red color on the picture):
  17-27 inch (43-68 cm)
• around the chest behind the front legs (green color on the picture):
  31-41 inch (79-104 cm)

Extra Large:

• around the neck of the dog (red color on the picture):
  24-33 inch (60-85 cm)
• around the chest behind the front legs (green color on the picture):
  35-51 inch (90-130 cm)