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Bra Size Converter

Unit Converters

Bust/underbust to CN/UK/EU/US sizes

Quick Answer

Bra Size Converter: Bust/underbust to CN/UK/EU/US sizes. Bra Size Converter uses standard unit conversion formulas to compute accurate results instantly.

CN / EU size75B
UK size34B
US size34B
Band (cm)75cm
Bust − underbust12.0cm

Calculation steps

  1. 1Difference = bust − underbust = 85 − 73 = 12.0 cm
  2. 2Nearest cup threshold: 12.0 cm ≈ 12.5 cm → cup B (each 2.5 cm = one cup)
  3. 3Band: underbust 73 cm rounds to nearest 5 → 75 cm; UK/US band = 34"
Difference (cm)CN/EU cupUKUS
7.5AAAAAA
10AAA
12.5BBB
15CCC
17.5DDD
20EDDDD (E)
22.5FEDDD (F)
25GFG
27.5HFFH
Measure underbust snugly after exhale, bust at the fullest point standing relaxed. Sister sizes share the same cup volume on adjacent bands (75B ≈ 70C ≈ 80A) — useful when a band feels tight or loose.

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How to Use

  1. Pick units: switch source and target units in the Bra Size Converter.
  2. Enter a value: results sync both ways instantly — no convert button needed.
  3. Use the reference table: common conversions are listed for instant lookup.
  4. Copy the result: copy the converted value with its unit.

Key Points

  • Bra Size Converter is a free online unit conversion tool — open and use, no sign-up.
  • All calculations run locally in your browser; your data never leaves the device.
  • Key capability: Bust/underbust to CN/UK/EU/US sizes.
  • Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Bra Size Converter formula

Bra Size Converter uses standard unit conversion formulas to compute accurate results instantly.

FAQ

How do I use the Bra Size Converter?
Open the page and fill in the input fields — results update automatically. Bust/underbust to CN/UK/EU/US sizes.
Are the results accurate?
Yes. Standard formulas and conversion factors are used and verified.
Is it free? Do I need to sign up?
Completely free. No registration, login or download required.
Does it work on mobile?
Yes. The responsive design works on phones, tablets and desktops.
Is my data saved?
No. Everything runs locally in your browser.

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Source & Updates

Based on SI conversion factors and international standards. Last updated: 2025-07

Authoritative sources:

Last updated:

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Maintained and periodically reviewed by the YiJianSuan editorial team — review process in ourEditorial Policy.

Cite this page: YiJianSuan. Bra Size Converter[EB/OL]. https://www.yijiansuan.com/en/c/convert/bra-size

Results provided by this tool are for reference only and do not constitute professional advice.