Complete User Guide
What is Bra Size?
Bra size consists of two components: the band size (number) and the cup size (letter). The band size is the measurement around your ribcage, typically ranging from 28 to 50. The cup size represents the difference between your bust and band measurements, ranging from AA to N.
Bra Size = Band Size + Cup Size
Understanding your correct bra size is essential for comfort, support, and proper fit. This calculator helps you determine your bra size accurately using standard measurement methods.
How to Use This Calculator
- Select the calculation type: Calculate Bra Size, Size Conversion, or Sister Sizes.
- Enter your measurements (underbust and bust) or bra size based on your selected calculation type.
- Select your preferred sizing system (US, UK, EU, FR, or AU).
- Click 'Calculate' to see your results.
- Review the detailed breakdown, size comparisons, and step-by-step solution.
Calculation Types
Calculate Bra Size
Calculate your bra size from underbust and bust measurements. Get your size in all sizing systems, sister sizes, and detailed calculations.
Size Conversion
Convert bra sizes between different sizing systems (US, UK, EU, FR, AU). Useful when shopping from international brands.
Sister Sizes
Find sister sizes (alternative sizes with the same cup volume). Useful when your regular size is not available or for trying different fits.
Sizing Systems
US Sizing:
Uses band sizes 28-50 and cup sizes AA, A, B, C, D, DD, DDD, G, H, I, J, K, L, M, N.
UK Sizing:
Uses the same band sizes as US but different cup progression: D, DD, E, F, FF, G, GG, H, HH, J, JJ after C.
EU/FR Sizing:
EU uses similar cup sizes to US. FR uses cm-based band sizes (add 15 to US band size) and similar cup progression.
AU Sizing:
Similar to UK sizing system with the same band and cup size progression.
PK (Pakistan) Sizing:
Uses UK sizing system. Same band sizes and cup progression as UK (D, DD, E, F, FF, G, GG, H, HH, J, JJ).
CA (Canada) Sizing:
Uses US sizing system. Same band sizes and cup progression as US (D, DD, DDD, G, H, I, J, K, L, M, N).
IN (India) Sizing:
Uses UK sizing system. Same band sizes and cup progression as UK.
NZ (New Zealand) Sizing:
Uses UK sizing system. Same band sizes and cup progression as UK.
IT/ES/DE (Italy/Spain/Germany) Sizing:
Uses EU sizing system. Same band sizes and cup progression as EU.
JP/CN (Japan/China) Sizing:
Uses similar sizing to EU system. Same band sizes and cup progression as EU.
BR (Brazil) Sizing:
Uses EU sizing system. Same band sizes and cup progression as EU.
MX (Mexico) Sizing:
Uses US sizing system. Same band sizes and cup progression as US.
ZA (South Africa) Sizing:
Uses UK sizing system. Same band sizes and cup progression as UK.
How to Measure
Underbust Measurement
Measure around your ribcage, directly under your bust. Keep the tape measure level and snug but not tight. This measurement determines your band size.
Bust Measurement
Measure around the fullest part of your bust, typically at nipple level. Keep the tape measure level and parallel to the ground. Wear a non-padded bra for accurate measurement.
Important Notes
- Measurements should be taken while wearing a non-padded, well-fitting bra for the most accurate results.
- Bra sizes can vary between brands. Always try on bras when possible, and use sister sizes if your regular size doesn't fit.
- If you're between sizes, try both the calculated size and sister sizes to find the best fit for your body shape.
Frequently Asked Questions
How do I measure my bra size?
Measure your underbust (ribcage) snugly around your torso, and your bust at the fullest point. The difference between these measurements determines your cup size, while your underbust measurement determines your band size.
What is a sister size?
Sister sizes are bra sizes with the same cup volume but different band and cup combinations. For example, 34C, 32D, and 36B are sister sizes. They can be useful if your regular size is not available.
How do I convert between US and UK bra sizes?
US and UK bra sizes use the same band sizes, but cup sizes differ after D. US uses D, DD, DDD, G, H, while UK uses D, DD, E, F, FF, G, GG, H. Use our size conversion tool for accurate conversions.
What is the difference between band size and cup size?
Band size is the measurement around your ribcage (underbust), typically 28-50. Cup size is determined by the difference between your bust and band measurements, ranging from AA to N.
Should I measure with or without a bra?
For the most accurate measurement, wear a non-padded, well-fitting bra. The bra should not add extra volume. Measure your underbust snugly and your bust at the fullest point while wearing the bra.
Why does my bra size vary between brands?
Bra sizing can vary between brands due to different manufacturing standards, materials, and fit preferences. Always try on bras when possible, and use sister sizes if your regular size doesn't fit in a particular brand.