Bra Size Calculator
Measure snugly around ribcage, just under the bust
Measure around fullest part of bust, keeping tape parallel
How to Measure
1. Underbust (Band Size)
Wrap the measuring tape snugly around your ribcage, directly under your bust. The tape should be level and parallel to the ground. Exhale and note the measurement.
2. Bust (Cup Size)
Measure around the fullest part of your bust, usually at nipple level. Keep the tape parallel to the ground and don't pull too tight.
Cup Size Guide
Related Calculators
Understanding Bra Sizing
Bra sizing consists of two components: the band size (number) and the cup size (letter). The band size corresponds to your underbust measurement, while the cup size is determined by the difference between your bust and underbust measurements.
Sister Sizes Explained
Sister sizes are bras with different band/cup combinations that have the same cup volume. For example, 34C, 32D, and 36B all have the same cup volume. This is useful when:
- Your usual band size feels too tight or loose
- A specific size is unavailable
- Different brands fit differently
Size Conversion Chart
| US | UK | EU |
|---|---|---|
| 32 | 32 | 70 |
| 34 | 34 | 75 |
| 36 | 36 | 80 |
| 38 | 38 | 85 |
| 40 | 40 | 90 |
Fitting Tips
This calculator provides a starting point. Fit can vary between brands and styles. Always try on bras before purchasing when possible. A well-fitting bra should have the band sitting level around your body, cups that fully contain breast tissue without gaps or spillage, and straps that stay in place without digging in.
Frequently Asked Questions
How do I measure my bra size at home?
To measure your bra size at home, you need two measurements: underbust (band size) and bust (cup size). For underbust, wrap the tape snugly around your ribcage directly under your bust. For bust, measure around the fullest part of your chest. The difference between these measurements determines your cup size (1 inch = A cup, 2 inches = B cup, etc.).
What are sister sizes in bras?
Sister sizes are bras with different band/cup combinations that have the same cup volume. For example, 34C, 32D, and 36B all have equivalent cup volumes. If your usual size feels too tight in the band, try going up a band size and down a cup size (34C to 36B). If the band feels loose, go down a band size and up a cup size (34C to 32D).
How do US, UK, and EU bra sizes differ?
US and UK bra sizes use similar band numbers but differ in cup progression after D (US uses DD, DDD, G while UK uses DD, E, F). EU sizes use centimeter-based band sizes (70, 75, 80 instead of 32, 34, 36) and different cup letters. Always check the size chart for the specific brand as sizing can vary.
How often should I get remeasured for a bra?
You should remeasure your bra size at least once a year, or after significant weight changes (gain or loss of 10+ pounds), pregnancy, breastfeeding, hormonal changes, or starting/stopping birth control. Your bra size can change throughout your life, so regular measurements help ensure proper fit and support.