A bra size combines underbust circumference and cup volume. Using only a clothing size or cup letter easily produces the wrong result.
Measure the underbust
Place the tape directly under the bust, parallel to the floor and close without compressing. This measurement guides the band, which should provide most support without riding up.
Measure the full bust
Measure around the fullest point without flattening the tissue. The difference from the underbust helps determine cup volume, while national systems use different progressions.
Sister sizes
Increasing the band while reducing the cup, or the reverse, can keep a similar cup volume. A sister size is not identical: band tension and wire shape change.
Signs of poor fit
The band rides up, the wire sits on breast tissue, the centre does not tack, or the cup cuts in or gapes. Straps should not compensate for a loose band.
- Check each brand’s own guide.
- Try different shapes, not only different sizes.
- A professional fitting can prevent repeated returns.
A supportive bra should not need to be endured; it should remain stable without causing pain.