Same Letter.
Different Volume.
A 30D and a 40D are the same "cup letter" but hold very different volumes that's why comparing across brands and bands by letter alone doesn't work. This calculator estimates your actual cup volume in cc/ml so you can compare accurately, especially when shopping for reusable inserts or forms.
- ✓ Results in under a minute, no sign-up needed
- ✓ Works for band 28 46, cup AA J
- ✓ Useful for comparing sizes across bands
Estimate your cup volume
Select your current band and cup size.
How Cup Volume Is Estimated
Cup volume grows with both the cup letter and the band it's paired with each cup letter step adds roughly 130–150cc, and every 2" of band adds a further increment on top, since a bigger frame needs proportionally more volume for the same letter. Our estimate is a widely used approximation, not a lab measurement, so treat it as a comparison tool rather than an exact figure.
Approximate Volume Reference (Band 34)
| Cup | Approx. Volume (cc) |
|---|---|
| A | ~250 |
| B | ~380 |
| C | ~510 |
| D | ~640 |
| DD | ~770 |
| DDD/F | ~900 |
Frequently Asked Questions
Why does volume matter if I already know my letter?
Letters aren't comparable across bands volume is the only way to fairly compare a 30D to a 38D.
Is this the same as breast implant sizing (cc)?
Not directly implant cc refers to implant volume, not total breast volume, though the two scales are often compared loosely.
Why do two 34D bras feel different?
Cup shape (shallow vs. full-on-bottom) affects fit even at the same volume volume is one factor, not the whole picture.