How to measure yourself for a dress that fits
Bust, waist, hip: three numbers and a soft tape.

Measure over light clothing, tape snug but not tight. Bust at the fullest point, waist at the narrowest, hip at the widest. Compare all three to the size chart and pick the size that fits your largest measurement.
Between two sizes?
For wrap and stretch styles go down for a closer fit. For woven dresses go up for ease.

