Measure with the ruler around the bust/waist/hips and keep the ruler parallel to the ground.
Find the closest size to your bust/waist/hips circumference in the size table below (the bust/waist/hips circumference values in the table point to your figure size).
The measurements of the model in the picture: Height ( 67.3″ ), Bust ( 41.7″ ), Waist ( 33.9″ ), Hips ( 47.2″ ). Wearing size: 18 / XL