Online universal bra size converters are located at Sizeguide.net, HerRoom and 85B. Each website uses a different method to convert a country's bra size to a different country's measurement.
Sizeguide.net offers two different tables, the first listing cup sizes and the second listing band sizes. Each table lists the U.S. cup or band sizes in the first column and then lists the United Kingdom, France, Spain, Japan and Australia's conversions in the proceeding columns.
HerRoom uses body measurements to calculate sizes and also uses conversion tables to convert from U.S. band and cup sizes to other countries' band and cup sizes.
85B has users enter their bra sizes in the field for their country, then converts it to five other countries' measurement styles.