Bra Size Calculator
Free Bra Size Calculator for health & fitness. Enter your measurements for personalized results with clear explanations and reference ranges.
Formula
Cup Size = Bust Measurement - Band Measurement
Measure band snugly under bust, measure bust at fullest point. The difference in inches determines cup size (1 inch=A, 2 inches=B, etc.).
Worked Examples
Example 1: Standard Calculation
Problem:Band measure: 30 inches, Bust: 34 inches.
Solution:Band size = 30 (round to even)\n\nDifference = 34 - 30 = 4 inches\n\n4 inches = D cup\n\nSize: 30D
Result:30D
Example 2: Sister Size Example
Problem:Wearing 34B but band feels loose.
Solution:Current: 34B\nBand loose → go down in band\n\nSister size down: 32C\n(Same cup volume, tighter band)\n\nTry 32C for better support.
Result:Try 32C
Example 3: Metric Conversion
Problem:Band: 75 cm, Bust: 90 cm.
Solution:Convert to inches:\nBand: 75 ÷ 2.54 ≈ 29.5 → 30\nBust: 90 ÷ 2.54 ≈ 35.4\n\nDiff = 35 - 30 = 5 inches = DD\n\nSize: 30DD (US) or 65E (EU)
Result:30DD / 65E
Frequently Asked Questions
How do I measure my bra size?
Measure band: around ribcage, directly under bust, snugly. Measure bust: around fullest part, loosely. The difference determines cup size. Wear an unpadded bra or no bra.
Why doesn't my calculated size feel right?
Sizing varies by brand. Breast shape, spacing, and fullness affect fit beyond size. Try your calculated size plus sister sizes. Consider professional fitting for best results.
How should a properly fitting bra feel?
Band: snug, parallel to floor, 2 fingers fit underneath. Cups: no spillage or gaping. Straps: supportive but not digging. Center: sits flat against sternum.
What is band size?
Band size is the circumference of your ribcage just below the bust, measured in inches (US/UK) or centimeters (EU). It should be snug for support.