Newborn: 5 ¼” (13.33 cm) x 5 ½” (14 cm)
0-3 Month: 5 ½” (14 cm) x 6” (15.25 cm)
3-6 Month: 5 ¾” (14.5 cm) x 6 ¼” (16 cm)
6-9 Month: 6 ¼” (16 cm) x 6 ¾” (17 cm)
9-12 Month: 6 ¾”, (17 cm) x 7” (17.75 cm)
1-2 Years: 7” (17.75 cm) x 7 ¼” (18.5 cm)