Bra Size Calculator
Convert bust and underbust measurements into a starting bra size, convert between US/UK/EU systems, and get support recommendations.
US Size
32DDD / F
Conversions
UK: 32DDD/F
EU: 68DDD/F
Support Tip
Specialty and full-support bras with reinforced bands and straps are recommended.
How to Use This Calculator
Measure underbust snugly
Keep the tape parallel to the ground, breathe out gently, and record the measurement.
Measure bust comfortably
Wrap the tape around the fullest part of your bust while wearing a lightly lined bra.
Review size and support tips
Use the suggested size as a starting point and try multiple bras—brands vary in fit.
Formula
Band Size = nearest even number of underbust
Cup Size = Bust − Band → lookup cup letter
Example: Underbust 31.3 → band 32. Bust 38 → difference 6 → cup DDD/F. US size = 32F.
Conversions: UK uses double letters (DD, FF). EU bands convert to centimeters with (Band × 2) + 4.
About the Bra Size Calculator
Bra sizing varies between brands and countries. This calculator uses the classic measuring method to recommend a starting point, so you can shop with confidence or adjust patterns when sewing bras or swimwear.
When to Use This Calculator
- Shopping for bras: Reset your baseline size before trying new brands.
- Nursing or pregnancy: Track size changes as your body transitions.
- Sewing lingerie: Select pattern size and adjust cup volume.
- Chest measurement updates: See how weight fluctuations affect size.
Why Use Our Calculator?
- ✅ Measurement-first: Avoid guesswork when switching brands.
- ✅ Global conversions: View US, UK, and EU size equivalents.
- ✅ Support tips: Suggested bra types based on cup-to-waist ratio.
- ✅ Mobile friendly: Measure and compute in dressing rooms.
Common Applications
Fit experts: Verify measurements before fittings.
Lingerie designers: Convert measurements into international size codes.
Customers: Understand why bra sizes may differ between stores.
Tips for Best Results
- Measure twice for accuracy, keeping the tape level and snug but not tight.
- Round up if you fall between cup sizes—you can size down when trying bras.
- Remember band size controls support. If the band feels loose, reduce the band and increase the cup (the “sister size” rule).
- Different styles (sports, balconette, plunge) fit differently—use this as a baseline.
Frequently Asked Questions
What if my measurements fall between cup sizes?
Try the larger cup first. You can adjust by using “sister sizes” (e.g., 34D ≈ 32DD). Comfort and support are the final decision-makers.
How does this method compare to professional fittings?
Boutiques may use slightly different formulas or take additional measurements. This method provides a commonly used starting point so fittings go faster.
Can I enter centimeters?
Currently the inputs expect inches. Convert centimeters to inches by dividing by 2.54, or you can modify the calculator to accept metric values.
What are sister sizes?
Sister sizes have the same cup volume but different band length. If 34C is loose, try 32D; if it’s tight, try 36B.