40-Inch Underbust Bra Size
A snug 40″ underbust (102 cm) is a 40 band. Slide to your bust measurement and the size appears; the table shows every cup a 40 band can carry.
My underbust is 40″: what's my size?
The band comes from the underbust alone. 40″ → 40 band whatever your bust; the bust only decides the cup letter: one letter per inch above 40.
Where 40″ lands
A 40 band in every system
Odd number? No. 40 is the 40 band directly. Bands are always even; the underbust reading between them goes to the sister size that fits.
Getting the underbust right
Firm against the ribs, level all the way round, on a normal exhale. A slack tape adds an inch and a band size.
Nearest whole inch, odd rounds up to even. Never add four inches: that is the outdated rule.
The band should fasten on the loosest hook and feel firm; move inward as it stretches over months.
Full technique with diagrams: how to measure your bra size.
40-inch underbust: answered
What band size is a 40 inch underbust?
A 40 band. Even readings are the band directly.
What bra size is a 40 inch underbust and a 43 inch bust?
40C: a three-inch difference on a 40 band. Bust 44 would be 40D, 42 would be 40B.
What is a 40 band in EU sizing?
EU 90 (US band × 2.5 − 10); FR 105; AU 18; IT 6.
Should the tape be tight for the underbust?
Snug: firm against the ribcage like a well-fitting band, not painful. Two inches of slack turns a 34 band into a 36.
Can a 40 inch underbust wear a 38 band?
Often, as a sister size. 38 with one cup letter up holds the same volume on a firmer band, useful if 40 rides up or you are between readings.
Opens HauteFlair’s own hub page; use your measured size there. HauteFlair is owned by the same company as Brasize.ai; that relationship never changes the sizing math, charts, or fit advice on this page. How this site makes money.