Bra Size Calculator

Bra Size – Quick Cheat Sheet

Measure Underbust (snug): level tape right under the bust, exhale gently.
Measure Bust (standing): tape at fullest point, parallel to floor, not tight.
Band (US/UK): round underbust to the nearest even inch (e.g., 31.5″ → 32).
Cup: compute bust − band in inches. Round to ~nearest inch.
0–0.5 → AA, 1 → A, 2 → B, 3 → C, 4 → D, 5 → DD/E, 6 → DDD/F, 7 → G, 8 → H, 9 → I, 10 → J, 11 → K, 12 → L, 13 → M, 14 → N, 15 → O, and so on up through very large cups (P, Q, R, S, T, U, V, W, X, Y, Z) for larger differences.
Sister sizes: down band/up cup (tighter) or up band/down cup (looser).
Reality check: Brands and cuts vary. Use this as a starting point; try adjacent sister sizes.
Units: You can enter inches or centimeters; conversions are internal.

Single	C D E F G H I J K L M N O P Q R S T U V W X Y Z
Double	DD EE FF GG HH II JJ KK LL MM NN OO PP QQ RR SS TT UU VV WW XX YY ZZ
Triple	DDD EEE FFF GGG HHH III JJJ KKK LLL MMM NNN OOO PPP QQQ RRR SSS TTT UUU VVV WWW XXX YYY ZZZ
Metric (EU-style letters)	C D E F G H I J K L M N O P Q R S T U V W X Y Z

Notes & edge cases

This tool avoids the old “+4” rule. It uses the underbust itself to determine band.
If your difference lands between sizes, try both neighboring cups (and sister sizes).
For very small differences (≤0.5″), AA is suggested; some brands label as “Nearly A”.