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. The hips are measured from side seam to side seam across the front at the hem.  
X-Small: Bust is 22" (44" around), Length is 28"; Hips are 24.5" (49" around)
Small: Bust is 23" (46" around), Length is 28"; Hips are 24.5" (49" around)
Medium: Bust is 24" (48" around), Length is 28";Hips are 25" (50" around)
Large: Bust is 25" (50" around), Length is 29"; Hips are 27" (54" around)
X-Large: Bust is 26" (52" around), Length is 30"; Hips are 27.5" (55" around)
1x: Bust is 27" (54" around), Length is 30"; Hips are 29" (58" around)