The bust is measured from underarm seam to underarm seam across the front. Double to get the circumference. The length is measured from the shoulder seam straight down to the hem.
X-Small: Bust is 22.5" (45" around), Length is 28.5"
Small: Bust is 23.5" (47" around), Length is 29"
Medium: Bust is 24.5" (49" around), Length is 29.5"
Large: Bust is 26" (52" around), Length is 31"
1X: Bust is 29.5" (58" around), length 33"