Bra Size Calculator
Find your perfect bra size with accurate underbust and bust measurements
Measure around your ribcage, directly under your bust
Measure around the fullest part of your bust
Your Bra Size (US)
Band • Cup
Band Size
Based on underbust measurement
Cup Size
inch difference
Sister Sizes
These sizes have the same cup volume as your calculated size:
Cup Size Reference
| Difference | Cup Size | Description |
|---|---|---|
If you like this calculator
Please help us simply by sharing it. It will help us a lot!
Related Calculators
Other calculators you might find useful.
About Bra Size Calculator
Finding the right bra size is essential for comfort, support, and confidence. This calculator helps you determine your accurate bra size using two simple measurements.
How to Measure for Bra Size
Step 1: Measure Your Band Size (Underbust)
- Wrap a soft measuring tape around your ribcage, directly under your bust
- Keep the tape level and snug but not too tight
- Record the measurement in inches
Step 2: Measure Your Bust
- Wrap the tape around the fullest part of your bust
- Keep the tape level across your back
- The tape should be loose enough not to compress your breasts
Understanding Your Results
Band Size
Your band size is your underbust measurement rounded to the nearest even number. This is the number in your bra size (e.g., 32, 34, 36).
Cup Size
Cup size is determined by the difference between your bust and band measurements. Each inch of difference corresponds to a cup letter.
| Difference | US Cup Size |
|---|---|
| 1 inch | A |
| 2 inches | B |
| 3 inches | C |
| 4 inches | D |
| 5 inches | DD/E |
| 6 inches | DDD/F |
| 7 inches | G |
| 8 inches | H |
Sister Sizes
Sister sizes are bra sizes with the same cup volume but different band sizes. If your calculated size doesn't fit perfectly, try a sister size. For example, 34C has the same cup volume as 32D and 36B.
Tips for a Perfect Fit
- The band should be snug and level around your body
- The cups should fully contain your breast tissue without gaps or spillage
- The straps should not dig into your shoulders
- The center gore should lie flat against your sternum
When to Remeasure
Consider remeasuring your bra size:
- Every 6-12 months
- After significant weight changes
- During pregnancy and nursing
- After hormonal changes
Note: Bra sizing can vary between brands. Use this calculator as a starting point and try on different styles to find your perfect fit.
How the Calculation Works
Band Size Formula
Band Size = Underbust measurement rounded to nearest even number
Cup Size Formula
Cup Size = Bust measurement - Band Size
Each inch of difference equals one cup size (1"=A, 2"=B, 3"=C, etc.)
⚠️ Important Notes
- Bra sizes vary between brands and styles
- This calculator uses US sizing - UK/EU sizes differ
- Consider trying sister sizes for the best fit
- A professional fitting is recommended for best results