Women's gowns must be worn over 18th century stays. To get the measurements for proper sizing please put on the stays you intend on wearing with this gown. If possible, have another person take the measurements for you.
To measure your bust, take the tape around the widest part of your chest.
For the waist, hold the tape naturally, without pulling overly tight, around the smallest part of your natural waist, below the ribs and above the hip bones.
To measure your bicep, hold the arm in a relaxed position and hold the tape snuggly but not tightly around the widest part of the bicep.
When measuring waist to ankle, use the same location on your natural waist and measure down to the ankle bone.