Bra Size Calculator

This calculator converts two tape-measure numbers -- Band Measurement and Bust Measurement, both in inches -- into a US bra size plus UK and EU equivalents and two sister sizes, using lookup tables rather than a single formula for every field. Band size starts from Band Measurement rounded to the nearest whole inch; if that rounds to an odd number the calculator bumps it up by one so the reported band is always even, then clamps the result to the 28-48 range the calculator supports (lines 7-10). Bust Measurement plays no role in the band figure -- only the difference between Bust and Band Measurement, rounded to the nearest whole number, selects the cup, by indexing into a fixed 12-entry list running AA, A, B, C, D, DD/E, DDD/F, G, H, I, J, K, with any difference below 0 or above 11 clamped to the nearest end of that list (lines 12-16).

UK Size reuses the same band number and the same numeric cup index but reads from a separate letter list -- the two agree only through D; past that point UK uses DD, E, F, FF, G, GG, H, a list that never realigns with the US letters again (lines 18-20). EU Size converts the already-clamped US band to centimeters and rounds to the nearest 5, then applies a third cup list that matches the US letters at both ends -- AA through D, and again from G through K -- but uses plain E and F instead of the combined US labels DD/E and DDD/F for the two sizes in between (lines 22-28). Sister Size Smaller and Sister Size Larger step the band two sizes in one direction and the cup one size in the other, but that arithmetic is not re-clamped to the 28-48 band range, so a sister size computed from a band already sitting at 28 or 48 can report a band outside that range (lines 30-37).