Complete Guide to the Chinese Bra Size Calculator
What is Chinese bra sizing?
Chinese bra sizes typically combine a numeric band and a cup letter. The numeric part usually represents the underbust in centimeters, commonly rounded to a nearby 5 cm step such as 70, 75, 80, 85, and so on. The cup letter is based on the difference between full bust and underbust. A larger difference means a larger cup letter.
A common reason people search for a Chinese bra size calculator is that many brands and marketplaces list sizes in local formats that differ from US or UK labeling habits. Even when two bras have the same-looking size code, pattern shape, wire width, and cup depth can vary by manufacturer. That is why a calculator should be treated as a starting estimate, followed by fit checks and brand-specific reviews.
How this calculator works
This calculator uses two measurements: underbust and full bust. First, it converts values to centimeters if you entered inches. Next, it rounds underbust to the closest 5 cm to estimate the Chinese band. Then it computes the cup difference:
Cup Difference = Full Bust (cm) − Underbust (cm)
Finally, it maps that difference to the nearest common cup step (AA, A, B, C, D, E, F, and higher). The result is displayed as a combined size such as 75B, 80C, or 85D.
Step-by-step measuring method
Accurate measuring is the foundation of accurate bra sizing. Use a soft tailor tape, a mirror, and if possible ask someone to help check tape alignment.
- Wear a thin, non-padded bra or bralette for measurement.
- Measure underbust firmly and parallel to the floor.
- Measure full bust at nipple level without compressing tissue.
- Write down both numbers and repeat once or twice.
- Average your readings if they vary slightly.
If your calculated size feels close but not perfect, try the neighboring cup or sister size. Body shape, breast root width, asymmetry, and bra style all influence final comfort.
Chinese size conversion tips (CN vs US/UK/EU)
Band and cup systems are not perfectly identical across countries. Chinese sizing usually aligns more closely with centimeter-based systems. US and UK bands are often labeled in inches and use even numbers (32, 34, 36, etc.). Cup lettering after D may diverge between brands and markets.
| CN Band (cm) | Approx. US/UK Band | Notes |
|---|---|---|
| 70 | 32 | Approximate conversion |
| 75 | 34 | Common equivalent |
| 80 | 36 | Check brand chart |
| 85 | 38 | Fit may vary by style |
| 90 | 40 | Use return-friendly sellers |
Always verify the seller’s own chart before ordering. Some brands run tight in the band, while others have shallower or deeper cups than average.
How to know your bra fits correctly
A well-fitted bra should feel supportive without pain. Use this quick checklist:
- The center gore lies flat against your sternum (for wired bras).
- The underband sits level around your torso and does not ride up.
- Cups contain breast tissue without spillage or gaping.
- Straps stay in place without digging deeply into shoulders.
- You can move, raise arms, and breathe comfortably.
If the band rides up, try a smaller band or tighter hook. If cups wrinkle, try a smaller cup or a different shape. If tissue spills over the top or sides, go up a cup or switch to a fuller coverage design.
Common sizing mistakes and easy fixes
| Problem | Likely Cause | Fix |
|---|---|---|
| Band rides up | Band too loose | Go down one band size |
| Top spillage | Cup too small | Go up one cup |
| Cup wrinkles | Cup too large or mismatch shape | Try smaller cup or different style |
| Straps digging | Band not supporting enough | Adjust straps, possibly tighter band |
| Underwire poking | Wrong cup volume/width | Try larger cup or wider wire style |
Online shopping checklist for Chinese bra sizes
- Compare your calculator result with the brand’s chart.
- Read reviews for notes like “runs small” or “shallow cups.”
- Check fabric stretch and closure rows.
- Prefer stores with clear return/exchange policy.
- Order one nearby sister size if uncertain.
A calculator gives a strong first estimate, but the final best size depends on brand pattern and your breast shape. Using both measurement math and fit testing gives the most reliable outcome.
Frequently Asked Questions
Is this Chinese bra size calculator accurate?
It gives a practical estimate based on common CN sizing logic. Final fit can vary by brand and bra style, so consider trying one nearby size as backup.
Should I measure with or without a bra?
Use a thin, non-padded bra or bralette for better shape consistency. Avoid heavily padded or push-up bras while measuring.
What if my underbust is between two band sizes?
Try the nearest band first. If the band feels too tight, move up one band and down one cup (sister size). If too loose, do the reverse.
Does cup letter mean the same volume in every band?
No. Cup volume changes with band size. For example, 75C and 80B are often sister sizes with similar cup volume but different band lengths.
Why do two bras in the same size fit differently?
Different brands use different patterns, wire widths, cup depth, and fabrics. Size labels are only part of fit.
How often should I re-measure?
Every 6–12 months, or after weight changes, hormonal changes, pregnancy, or noticeable fit issues.