The average size baby is born 7.5 lbs and grows approximately 1.5 to 2 lbs each month, and 1 to 1 ½ inches in height each month.

3-6 months = Chest: 12-14 inches Height: 20-24 inches Weight: 12-17 lbs

Size translation: Buy this size when you want Mom and Dad to dress the babe up in your purchase for Instagram stories; and, for those fun early refrigerator magnet pictures with Granny and Grandpa!

6-12 months = Chest: 14-16 inches Height: 25-28 inches Weight: 17-21 lbs

Size translation: Buy this size when you cannot make the baby shower. Mom and Dad will appreciate it!

12-18 months = Chest: 16-18 inches Height: 29-31 inches Weight: 22-24 lb

Size translation: Buy this size when you cannot remember when the baby was born—but you think--in the last year and a half! Or, pop into the 2T toddler t-shirt section.

2T = Chest 20 - 21 inches Height 32 - 36 inches Waist 19 - 20 inches

Size translation: Buy this size when you want a t-shirt for a 2 year old. This size can also be worn as a beach cover-up.

4T = Chest 22 - 23 inches Height 36 - 40 inches Waist 20.5 - 21 inches

Size translation: Buy this size for a big 3 year old and a 4 year old.

6T = Chest 24 - 25 inches Height 40 - 43 inches Waist 21.5 - 22 inches

Size translation: Buy this size for a big 5 year old and a 6 year old.