🎀 Bra Size Calculator
Bra sizing comes down to two numbers: the band (underbust) rounded to an even size, and the cup, which is the difference between bust and band — one inch per letter. Measure snugly with a soft tape and enter both values.
Sizing varies between brands and countries, so treat the result as a starting size for fitting rooms, not a final verdict.
How to use this calculator
Measure under your bust and around the fullest part of your bust with a soft tape, enter both numbers in inches, and read your band size and cup letter.
- Measure snugly around your ribcage just under the bust for the Band value.
- Measure around the fullest part of the bust for the Bust value.
- Enter both measurements in inches.
- Read the resulting size, shown as band number plus cup letter.
Frequently asked questions
How is the bra size calculated?
The band measurement is rounded to the nearest even number to get the band size. The cup comes from the difference between the bust and that band size, at one inch per letter: 1 inch is A, 2 is B, 3 is C, 4 is D, and so on.
Can you give a worked example?
A 32 inch band and a 36 inch bust gives band size 32 and a 4 inch difference, which is a D cup, so the result is 32D.
Why does it say the result is approximate?
Sizing systems differ between brands and countries, and body shape affects fit beyond two numbers. Use the result as your starting size in the fitting room.
What if my bust is barely larger than my band?
A difference under one inch maps to AA. If the bust is not larger than the band at all, the calculator asks you to recheck the measurements.