Bra Size Calculator
Find your perfect bra size with accurate measurements
Cup Size Reference
Difference between bust and band measurement
How to Use This Bra Size Calculator
- Select your measurement unit (inches or centimeters)
- Measure your band size: wrap a tape snugly around your ribcage, directly under your bust
- Measure your bust: wrap the tape loosely around the fullest part of your bust
- Enter both measurements and click calculate
- Review your size in US, UK, and EU systems plus sister sizes
Example: With a 32-inch band measurement and 36-inch bust measurement, the 4-inch difference indicates a D cup, giving you a US size of 32D (UK: 32D, EU: 70D).
Tip: Measure without a bra or in an unpadded bra for the most accurate results. Take measurements while exhaling normally.
Why Use a Bra Size Calculator?
Studies suggest up to 80% of women wear the wrong bra size, leading to discomfort, poor support, and unflattering fit.
- Find your correct size after weight changes, pregnancy, or hormonal shifts
- Convert between US, UK, and European sizing when shopping internationally
- Understand sister sizes when your usual size isn't available
- Get properly fitted before purchasing expensive bras or swimwear
- Identify the right sports bra size for adequate support during exercise
- Shop online with confidence by knowing your measurements across sizing systems
Understanding Your Results
Your bra size consists of a band number (ribcage circumference) and cup letter (difference between bust and band).
| Result | Meaning | Action |
|---|---|---|
| 0-1 inch difference | AA-A cup | Look for petite or small-bust specialty brands |
| 2-3 inch difference | B-C cup | Most common range, widely available in stores |
| 4-5 inch difference | D-DD cup | Ensure adequate support, especially for sports |
| 6+ inch difference | DDD/E and above | Consider specialty retailers for better fit and support |
Meaning: AA-A cup
Action: Look for petite or small-bust specialty brands
Meaning: B-C cup
Action: Most common range, widely available in stores
Meaning: D-DD cup
Action: Ensure adequate support, especially for sports
Meaning: DDD/E and above
Action: Consider specialty retailers for better fit and support
Note: Cup size is relative to band size. A 32D and 36B have the same cup volume but different band fits.
About Bra Size Calculator
Formula
Cup Size = Bust Measurement - Band Measurement Each inch of difference equals one cup size: 1" = A, 2" = B, 3" = C, 4" = D, 5" = DD, etc.
Current Standards: US sizing uses letters (A, B, C, D, DD, DDD), UK uses double letters after D (DD, E, F, FF, G), and EU uses sequential letters with metric band sizes.
Frequently Asked Questions
How often should I get re-measured?
Remeasure every 6-12 months, or after any significant body changes like weight fluctuation of 10+ pounds, pregnancy, breastfeeding, or hormonal changes from medication or menopause. Most women's bra size changes 6+ times throughout their life.
What are sister sizes and when should I use them?
Sister sizes share the same cup volume with different band sizes. For example, 34C, 32D, and 36B are sisters. If the band feels too tight but cups fit, try going up in band and down in cup. If the band is loose, go down in band and up in cup. This maintains cup volume while adjusting the band.
Why do bra sizes vary between brands?
There's no universal standard for bra sizing, and brands design for different body types. European brands often run smaller in the band, while some US brands run larger in cups. Always try on when possible, and don't be surprised if you're different sizes across brands.
How should a properly fitting bra feel?
The band should be snug on the loosest hook (allowing room to tighten as it stretches), lying parallel to the ground. Cups should fully contain breast tissue without spillage, gapping, or wrinkling. The center gore should lie flat against your sternum, and straps shouldn't dig in or slip off.
What's the difference between US and UK cup sizes?
US and UK sizes match through D cup. After D, US uses DD, DDD, G, H while UK uses DD, E, F, FF, G, GG, H. A US DDD equals UK E. Always check which sizing system a brand uses, especially when ordering online from international retailers.