Step 1: Wear your most comfortable, non-padded, and well-fitting bra that shapes your breasts the best.
Step 2: Use a measuring tape to measure under your torso underneath your bust, making sure to keep the tape horizontal. Save this measurement as your underbust measurement.
Step 3: Measure around the fullest part of your bust. Subtract this measurement from your underbust measurement, and save this number as your bust measurement.
Step 4: Determine your band and cup size by using the chart below.