Sister Size & International Converter
A 34DD, a 32F and a 70G can all be the same body — the letters differ because each country indexes its ladder from a different starting point. Enter a size in any run to get every equivalent, and the sister-size ladder that keeps cup volume constant when the band has to move.
Size run you are converting from
The number printed on the label, in the UK run.
Letters are ordinal positions, so the ladder changes with the run you pick.