How to Calculate Bra Size International Converter
What is Bra Size International Converter?
The Bra Size International Converter translates band and cup sizes across six major sizing systems: US (28-46 band, AA-J cup), UK (28-46 band, AA-H cup with FF/GG steps), EU (60-105 band, AA-K cup), French (75-120 band, similar cup to EU), Australian (6-24 band), and Japanese (60-105 band, similar to EU). Despite same letter-and-number format, each system measures and labels differently — a US 34B is NOT a UK 34B in actual fit.
Formula
- B
- Band Size (inches/cm) — Underbust circumference
- C
- Cup Size (letter) — Bust minus underbust difference
Step-by-Step Guide
- 1Enter band size and select system (most common: US, UK, EU)
- 2Enter cup letter and select cup system
- 3Calculator outputs equivalent band+cup in all 6 systems
- 4Note: US D = UK D, but US DD = UK DD = EU E (UK uses double letters at D+)
Worked Examples
Common Mistakes to Avoid
- ✕Assuming same number = same band size — US 34 = UK 34 yes, but EU 34 doesn't exist (band starts at 60)
- ✕Confusing cup conversion across systems — US DD = UK DD = EU E ≠ EU DD
- ✕Not professionally measured — most women wear wrong size (Wacoal studies: 80% wrong fit)
- ✕Buying based on number alone — fit is the band+cup combination
Frequently Asked Questions
How do I measure my bra size correctly?
Underbust (snug, exhaling): rounded to nearest even = band size. Bust (loose, standing straight): subtract underbust. Each 1-inch difference = 1 cup letter (A, B, C, D, etc.). 5 inches = E/DD. Most professional fitters use this method with adjustment for breast shape.
Why is sizing inconsistent across brands?
No regulatory standard. Each brand sets internal sizing. UK brands (Bravissimo, Panache, Curvy Kate) tend to run true to UK standards. US brands often vanity-size (run small numbers larger). EU brands follow strict EU/ISO standards.
Should I go up or down a band size?
Most fit advice: go down a band, up a cup. Modern professional fitting argues many women wear bands too loose. Going from 36B to 34C (sister size) maintains cup volume with tighter, more supportive band.
Ready to calculate? Try the free Bra Size International Converter Calculator
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