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 at the shortest point and longest point.  
XS: Bust is 23" (46" around), shortest length 32.5", longest length is 37"
S/M: Bust is 24' (48" around), shortest length is 33" longest lenth is 37.5"
L/XL: bust is 25.5"" (51" around), shortest length is 35" longest lenth is 38"
1X: bust is 26.5" (53" around), shortest length is 34" longest lenth is 39"