Lightly Lined Wireless Cotton Racerback Bra

What you'll need: A soft measuring tape, an unlined or lightly lined bra and, ideally, a mirror.

STEP 1 | THE UNDERBUST

Your underbust measurement is the circumference of your ribcage measured directly beneath your breasts. It is used to determine your band size.

How to measure your underbust:

1. Wrap the measuring tape flat under your breasts, parallel to the floor.
2. Breathe normally. Avoid taking a deep breath or holding your breath.
3. Take note of the measurement without pulling too tight or leaving too much slack. Between two sizes? Round up to the nearest measurement. Find out your band size.

STEP 3 | THE CUP

The cup indicates breast volume. You determine it by comparing your bust measurement to your underbust measurement.