Underbust

Underbust is the distance around the ribcage, just under the bust, with the tape snug. It sets the band size of a bra, and the gap between it and the bust gives the cup. Swimwear and sports bra charts often ask for it too.

How to measure

1. Wear an unpadded bra, or nothing.
2. Stand straight, arms down.
3. Place the tape just under the bust, where the band of a bra sits.
4. Keep it level all the way round, snug against the ribcage.
5. Breathe out normally and read. Note the unit.

The template step: "snugly around your ribcage, just under the bust."

On a size chart

Under EN 13402-3, the European band is the underbust rounded to the nearest 5 cm: an underbust of 76 cm is a 75 band, and the Bras template gives its 75 band an underbust of 73 to 77 cm. Charts that aren't sold by band list the underbust as a range per size. On the Sports bras template:

Its note reads "High-impact support: choose by underbust first." The Swimwear template has an underbust row too, from 66 to 70 cm (XS) to 86 to 91 cm (XL).

In Ruban Size

On a bra chart, Find my size asks for Underbust and Bust. The underbust counts most, and a band too loose counts against a size as much as one too tight, where on clothes too tight weighs more. On swimwear it counts beside the bust, waist and hips. The bra size calculator turns an underbust and a bust into a size with the EN 13402-3 rules, sister sizes included.