Cup Size Chart
This cup size chart shows every standard cup size from AA to K with the exact measurement difference, approximate volume, and equivalents in US, UK, and EU sizing systems. Use it as a quick reference alongside our bra size calculator for the most accurate fit.
The inch difference between bust and underbust determines your cup size
Complete Cup Size Reference
Each cup size corresponds to a specific inch difference between your bust and underbust measurements. This chart covers all standard sizes from AA through K, with the measurement difference, metric equivalent, naming conventions across three major sizing systems, and approximate volume at a 34 band.
| Cup | Difference (in) | Difference (cm) | US Name | UK Name | EU Name | Volume (34 band) |
|---|---|---|---|---|---|---|
| AA | <1" | <2.5 cm | AA | AA | AA | ~65 ml |
| A | 1" | 2.5 cm | A | A | A | ~130 ml |
| B | 2" | 5 cm | B | B | B | ~200 ml |
| C | 3" | 7.5 cm | C | C | C | ~275 ml |
| D | 4" | 10 cm | D | D | D | ~360 ml |
| DD | 5" | 12.5 cm | DD | DD | E | ~450 ml |
| DDD / F | 6" | 15 cm | DDD (F) | E | F | ~550 ml |
| G | 7" | 17.5 cm | G | F | G | ~660 ml |
| H | 8" | 20 cm | H | FF | H | ~780 ml |
| I | 9" | 22.5 cm | I | G | I | ~900 ml |
| J | 10" | 25 cm | J | GG | J | ~1030 ml |
| K | 11" | 27.5 cm | K | H | K | ~1170 ml |
Visual cup size comparison at the same band size. Each letter represents one additional inch of difference.
How Cup Volume Changes with Band Size
This cup size chart also shows how volume varies across different band sizes. The same cup letter holds different volumes depending on the band. A 32D is smaller than a 38D because the band circumference changes the cup proportionally. The table below shows approximate cup volumes in milliliters across common band sizes.
| Band | A Cup | B Cup | C Cup | D Cup | DD Cup |
|---|---|---|---|---|---|
| 30 | ~100 ml | ~160 ml | ~230 ml | ~310 ml | ~400 ml |
| 32 | ~115 ml | ~180 ml | ~250 ml | ~340 ml | ~430 ml |
| 34 | ~130 ml | ~200 ml | ~275 ml | ~360 ml | ~450 ml |
| 36 | ~150 ml | ~220 ml | ~300 ml | ~390 ml | ~480 ml |
| 38 | ~170 ml | ~245 ml | ~330 ml | ~420 ml | ~520 ml |
| 40 | ~190 ml | ~270 ml | ~360 ml | ~460 ml | ~560 ml |
How to Read This Cup Size Chart
To use this cup size chart, find your measurement difference in the first column. Read across to find your cup letter in each sizing system. The volume column gives you an idea of actual cup capacity at band 34. If your band size is different from 34, use the volume-by-band table above to see how your cup volume shifts.
For example, if your bust measures 37 inches and your underbust measures 33 inches, the 4-inch difference puts you at a D cup. Your underbust rounds to band 34, making your size 34D with an approximate volume of 360 ml.
Common Cup Size Misconceptions
One thing this cup size chart makes clear is how many common beliefs about cup sizes are simply wrong. Here are the most frequent misconceptions.
A D cup is not "big"
D represents just 4 inches of difference between bust and underbust. It is one of the most commonly worn sizes in the US. On a smaller band like a 30, a D cup looks quite modest. The perception of D as large comes from outdated sizing that pushed most women into A-D when the full range extends well beyond.
Cup size is not fixed
A D cup on a 32 band is physically smaller than a D cup on a 38 band. The letter only describes the proportional difference, not an absolute volume. Two people can both wear a D cup and have noticeably different breast sizes if their band sizes differ.
DD is not double D
DD is just one inch more than D, not twice the size. The jump from D to DD is the same single-inch increment as B to C or C to D. The name "double D" is misleading and contributes to the misconception that DD is dramatically larger than D.
There are sizes beyond DDD
US sizing goes to K and beyond. UK sizing extends even further with KK, L, and LL. Specialty brands like Elomi, Panache, and Goddess routinely manufacture sizes up to UK K cup. If you have been wearing a DDD because it was the largest in store, there may be a better-fitting size waiting.
Use this cup size chart alongside our calculator for the most accurate fit. For a breakdown of how each size actually looks and feels, see our cup size comparison.
Frequently Asked Questions
What is the biggest cup size?
In standard US sizing, K is the largest commonly available cup size, representing an 11-inch difference between bust and underbust. UK sizing extends further with KK, L, and LL. Specialty brands may offer even larger sizes for custom orders.
Is a cup size the same on every band?
No. As shown in our cup size chart above, cup volume increases as band size increases. A 34D holds more volume than a 30D because the larger band circumference stretches the cup proportionally. This is why sister sizing works — changing the band up or down while adjusting the cup letter in the opposite direction keeps the volume nearly the same.
What cup size is most common?
34DD is the most commonly purchased bra size in the US. However, fitting experts estimate that 80% of women wear the wrong size, so the true average may differ. Many women sized into a B or C at a department store find they are actually a D or DD when measured properly.