Items are measured laying flat. All measurements are in US units: Inches/feet/pounds
Bust: armpit to armpit
Hip: measured at bottom of zipper if present on skirt/dress/pants, if not present, then measured at widest portion of hip.
Sleeve: from top of sleeve seam to cuff
Length of shirt/dress/jacket/coat: from middle of shoulder seam to bottom (hem).
Shoulder: measured between shoulder seams in back.