CHEST Measure around the fullest part of your chest, keeping the measuring tape parallel to the floor. Think it may be too small? Take a seat, chests expand slightly when seated.
WAIST Measure around the smallest part of the waist (typically where your body bends side to side), making sure to not pull the tape too tight.
HIPS With feet together, measure around the fullest part of your hips, keeping the tape parallel to the floor.