US Bra Size to Japan Conversion Guide
Convert your US inch-based size into Japanese centimetre bands and streamlined cup letters. Use the chart, steps, and retailer tips to shop Japanese brands confidently.
Covers US bands 28–52 and Japanese bands 60–125 with cups AA through H.
Japan measures in centimetres
Bands appear in 5 cm steps—US 30 maps to JP 70, US 32 to JP 75, US 34 to JP 80, etc.
Single letters only
Japan removes double letters, so US DD becomes JP E and US DDD/F becomes JP F.
Check domestic size charts
Japanese retailers often display JP, EU, and US columns—confirm you’re referencing the JP column when converting.
US to Japanese band and cup mapping
Use the chart to translate the US band into centimetres and align the cup letter with Japanese notation.
| US label | JP label | Notes |
|---|---|---|
| 28AA | 70AA | US 28AA becomes JP 70AA once the band is converted to centimetres and double letters are removed. |
| 28A | 70A | US 28A becomes JP 70A once the band is converted to centimetres and double letters are removed. |
| 28B | 70B | US 28B becomes JP 70B once the band is converted to centimetres and double letters are removed. |
| 28C | 70C | US 28C becomes JP 70C once the band is converted to centimetres and double letters are removed. |
| 28D | 70D | US 28D becomes JP 70D once the band is converted to centimetres and double letters are removed. |
| 28DD | 70E | US 28DD becomes JP 70E once the band is converted to centimetres and double letters are removed. |
| 28DDD | 70F | US 28DDD becomes JP 70F once the band is converted to centimetres and double letters are removed. |
| 28G | 70G | US 28G becomes JP 70G once the band is converted to centimetres and double letters are removed. |
| 28H | 70H | US 28H becomes JP 70H once the band is converted to centimetres and double letters are removed. |
| 28I | 70I | US 28I becomes JP 70I once the band is converted to centimetres and double letters are removed. |
| 28J | 70J | US 28J becomes JP 70J once the band is converted to centimetres and double letters are removed. |
| 28K | 70K | US 28K becomes JP 70K once the band is converted to centimetres and double letters are removed. |
| 30AA | 75AA | US 30AA becomes JP 75AA once the band is converted to centimetres and double letters are removed. |
| 30A | 75A | US 30A becomes JP 75A once the band is converted to centimetres and double letters are removed. |
| 30B | 75B | US 30B becomes JP 75B once the band is converted to centimetres and double letters are removed. |
| 30C | 75C | US 30C becomes JP 75C once the band is converted to centimetres and double letters are removed. |
| 30D | 75D | US 30D becomes JP 75D once the band is converted to centimetres and double letters are removed. |
| 30DD | 75E | US 30DD becomes JP 75E once the band is converted to centimetres and double letters are removed. |
| 30DDD | 75F | US 30DDD becomes JP 75F once the band is converted to centimetres and double letters are removed. |
| 30G | 75G | US 30G becomes JP 75G once the band is converted to centimetres and double letters are removed. |
| 30H | 75H | US 30H becomes JP 75H once the band is converted to centimetres and double letters are removed. |
| 30I | 75I | US 30I becomes JP 75I once the band is converted to centimetres and double letters are removed. |
| 30J | 75J | US 30J becomes JP 75J once the band is converted to centimetres and double letters are removed. |
| 30K | 75K | US 30K becomes JP 75K once the band is converted to centimetres and double letters are removed. |
Convert your size in four steps
- Take accurate US measurements Measure snug underbust and bust in inches or use a US bra that already fits.
- Swap the band to centimetres Use the chart to find the matching Japanese band (65, 70, 75, etc.) and adjust the cup letter.
- Try sister sizes for fine-tuning If the converted band feels different, move one band up or down and offset with the sister cup.
- Review fabric and coverage Japanese bras can feature narrower wires or lighter padding—check reviews and try before keeping tags off.
Worked conversion examples
US 30DD -> JP 70E
US 30DD converts to JP 70E—centimetre band plus simplified cup.
US 32F -> JP 75G
US 32F maps to JP 75G for full-support Japanese styles.
US 34DD -> JP 80E
US 34DD becomes JP 80E, a common size for everyday Japanese bras.
US 36G -> JP 85H
US 36G translates to JP 85H, keeping equivalent volume.
Brand sizing cheat sheet
Use these retailer references when switching between US and Japanese labels.
US-based retailers
- Nordstrom
- Bare Necessities
- HerRoom
- Amazon US
Convert first when ordering Wacoal Japan or Peach John through US marketplaces.
Japanese brands
- Wacoal Japan
- Triumph
- Peach John
- Aimerfeel
Wacoal Japan, Triumph, Peach John, and Aimerfeel publish JP sizes first with limited US references.
International marketplaces
- Rakuten Global Market
- Amazon JP
- Zozotown
- YesStyle
Rakuten Global Market, Zozotown, and YesStyle offer JP labelling plus conversion charts.
Fit tips after converting
- Expect narrow wires or shallow cups on some JP styles—sister sizes help dial in coverage.
- Look for centimetre fit notes in product descriptions to confirm your converted band.
- Record both your JP and US equivalents for each brand to streamline future orders.
Helpful tools
Interactive bra size calculator
Measure in inches or centimetres and generate both local and international sizes in one place.
OpenInternational bra size guide
Compare regional systems side by side and review conversion advice for cross-border shopping.
OpenSister size navigator
Adjust bands tighter or looser while holding cup volume steady after you convert.
OpenUS to Japanese conversion FAQ
How are Japanese band numbers measured?
Japan labels the underbust in centimetres, typically in 5 cm steps (65, 70, 75, etc.).
Do Japanese cups follow the same letters?
Japan uses single letters without double steps. DD converts to E and DDD/F converts to F before continuing upward.
What about petite frames or tall torsos?
After converting, try sister sizes to find the best strap placement and underband tension for your frame.
Where can I buy Japanese-sized bras?
Shop domestic brands through Rakuten, Zozotown, Peach John, and major department stores that ship internationally.