Calculator · Reverse lookup

Bra Size to Bust Size

Already know a bra size? Enter it here to see the approximate bust measurement behind it — the reverse of the usual calculation.

Select a band and cup size to continue.

Approximate bust measurement
38″
For a 34C

Working backwards from a size

Most calculators go from measurements to a size. This one runs the other direction — enter a bra size you already know, and see roughly what bust measurement it implies. That's useful for buying a gift, comparing a size someone mentioned, or sanity-checking a size against your own measurements.

approximate bust ≈ band + cup difference (in inches)

Since the same size can be cut slightly differently between brands, treat the result as a useful estimate rather than an exact figure.

Questions

Bra size to bust size FAQs

It's handy for buying a gift, comparing a size mentioned by someone else, or checking a size against your own measurements without redoing the full calculation.

Very close — the band size is the underbust measurement rounded to the nearest standard size, usually an even number.

It's a solid estimate, but actual bust measurement can vary slightly by brand due to differences in cup cut and pattern.