Japan Bra Size Calculator & Converter
Calculate your Japanese bra size in centimetres, decode the JP cup system (AAA, AA, A–H — no DD notation), and convert instantly to US, UK, AU & EU — with sister sizes and Wacoal Japan, Triumph JP & Uniqlo fit notes.
How to measure correctly
- Wear a non-padded bra or no bra for accurate readings.
- Underbust: wrap tape snugly around your ribcage directly under the bust. Keep tape level all the way around. Exhale and measure in centimetres.
- Overbust: measure around the fullest part of your bust. Tape should be loose enough to slide a finger underneath.
- Stand naturally — don’t lift arms or lean forward. Both measurements in the same posture.
- Round to the nearest 0.5 cm for best accuracy.
International Size Conversions
Your Sister Sizes (Same Cup Volume)
Recommended Bras in Your JP Size
Top-rated Japanese brands available internationally — verified for JP sizing accuracy.
- JP bands 65–95, cups AA–F
- Seamless, wire-free comfort
- Wacoal Japan, Triumph JP styles
- JP bands 65–90, cups A–E
- Smooth finish, minimal seams
- Uniqlo, Peach John, Triumph JP
Measure in centimetres to get your accurate Japanese bra size
What Is the Japanese Bra Sizing System?
Japanese bra sizing uses centimetre-based band numbers (60, 65, 70, 75, 80, 85, 90…) paired with a unique single-letter cup sequence (AAA, AA, A, B, C, D, E, F, G, H) — no doubled letters, no DD or DDD notation. Band size is derived from your underbust measurement rounded to the nearest 5 cm, identical to the EU band system. Cup size is calculated from the difference between overbust and underbust in centimetres using 2.5 cm intervals starting from AAA. The system is codified under Japanese Industrial Standard JIS L 4006 and is used by Wacoal Japan, Triumph Japan, Peach John, Uniqlo, and Felissimo.
The Japanese bra sizing system shares its band logic with the EU system — both use centimetre-based numbers rounded to the nearest 5 cm. A woman with a 76 cm underbust has a JP band 75, identical to her EU band 75. However, the cup system is distinctly Japanese. Where the EU uses 2 cm cup increments and the UK uses 2.5 cm, the JP system also uses 2.5 cm intervals but begins from a much smaller starting point — AAA cup represents the smallest cup size, representing less than 7.5 cm of bust-to-underbust difference.
The most important difference between JP and other systems is the complete absence of doubled cup letters. Japan does not use DD, DDD, or FF. Instead, the progression runs AAA, AA, A, B, C, D, E, F, G, H — ten distinct cup sizes, each a single unique label. This means a JP E cup is a very specific size that cannot be confused with E in another country’s system — though the volume it represents differs from UK E, EU E, and AU E.
Japanese lingerie culture places particular emphasis on fit precision and comfort. Wacoal Japan, founded in Kyoto in 1949, pioneered scientific bra fitting research in Japan and produces internal sizing data covering millions of Japanese women. Their published research — including the ongoing “10 Year Survey” of breast shape and size changes in Japanese women — makes Wacoal the most data-informed lingerie brand in the world for Asian body types.
JP bands are underbust cm rounded to nearest 5 — identical to EU band logic.
JP cups start at AAA — no DD notation. Each step is approximately 2.5 cm of additional cup volume.
- JP bands are cm-based: 60, 65, 70, 75, 80, 85, 90, 95, 100 — identical rounding to EU bands
- JP cups use a unique single-letter sequence: AAA, AA, A, B, C, D, E, F, G, H — no DD, no DDD
- JP E cup = UK/AU E = EU F = US DDD — not identical to EU E or UK DD
- JP 75C = UK 34C = EU 75C = AU 10C — band converts the same as EU; cup C is the same in all systems
- Wacoal Japan and Triumph JP are the reference brands — their sizing defines the JP standard
How to Measure Your Japanese Bra Size
Japanese sizing requires centimetre measurements. You need your underbust (ribcage directly below the bust) and your overbust (fullest part of the bust), both in centimetres.
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Prepare correctly
Wear a non-padded bra or no bra. Stand naturally with arms relaxed. Padded bras add 2–4 cm to your overbust reading, shifting your JP cup by one or two letters. Wacoal Japan’s fitting guides specifically recommend measuring without any bra for most accurate results.
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Measure your underbust in centimetres
Wrap the tape snugly around your ribcage directly beneath your bust. Keep it level all the way around — not dipping at the back. Exhale fully and record to the nearest 0.5 cm. Your JP band size is your underbust cm rounded to the nearest 5: 74 cm rounds to JP 75, 77 cm rounds to JP 75 or 80 (try both).
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Measure your overbust in centimetres
Measure around the fullest point of your bust. Keep the tape horizontal and loose enough to slide one finger underneath — natural shape, not compressed. Record to the nearest 0.5 cm.
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Calculate your JP band
Round underbust to nearest 5 cm: 58–62 cm = JP 60, 63–67 cm = JP 65, 68–72 cm = JP 70, 73–77 cm = JP 75, 78–82 cm = JP 80, 83–87 cm = JP 85, 88–92 cm = JP 90, 93–97 cm = JP 95. If exactly on a boundary, try the smaller band first.
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Calculate your JP cup letter
Subtract underbust from overbust in cm, then match to the JP cup chart: under 7.5 cm = AAA, 7.5–10 cm = AA, 10–12.5 cm = A, 12.5–15 cm = B, 15–17.5 cm = C, 17.5–20 cm = D, 20–22.5 cm = E, 22.5–25 cm = F, 25–27.5 cm = G, 27.5+ cm = H. Each step is exactly 2.5 cm.
Wacoal Japan recommends measuring twice — once in the morning and once in the evening, as bust measurements can vary by up to 1.5 cm across the day due to hormonal fluctuations and posture changes. If your measurements straddle a cup boundary (e.g., exactly 15 cm difference), try JP B and JP C — the correct fit will be immediately obvious on the body.
Skip the calculation — use the calculator
Enter your measurements once and get your exact JP size plus conversions to UK, US, AU, EU and FR instantly.
Open the Japan Bra Size Calculator →Japanese Bra Size Chart (Underbust cm Reference)
This chart is the standard JP sizing reference aligned with JIS L 4006, used by Wacoal Japan, Triumph Japan, Peach John, and Uniqlo. The band system is identical to the EU band system.
Japanese sizes compared with UK, US, AU, and EU systems
| JP Band (cm) | Underbust (cm) | UK / US Band | AU Band | EU Band | FR Band |
|---|---|---|---|---|---|
| JP 60 | 53–57 | 28 | AU 4 | EU 60 | FR 75 |
| JP 65 | 58–62 | 30 | AU 6 | EU 65 | FR 80 |
| JP 70 | 63–67 | 32 | AU 8 | EU 70 | FR 85 |
| JP 75 | 68–72 | 34 | AU 10 | EU 75 | FR 90 |
| JP 80 | 73–77 | 36 | AU 12 | EU 80 | FR 95 |
| JP 85 | 78–82 | 38 | AU 14 | EU 85 | FR 100 |
| JP 90 | 83–87 | 40 | AU 16 | EU 90 | FR 105 |
| JP 95 | 88–92 | 42 | AU 18 | EU 95 | FR 110 |
| JP 100 | 93–97 | 44 | AU 20 | EU 100 | FR 115 |
Japanese Cup to UK, US, EU, AU Cup Conversion
The JP cup system starts at AAA and uses 2.5 cm intervals. Above C cup, JP letters begin to diverge from UK/AU, EU, and US — JP E is not the same as UK E or EU E. This table shows the exact volume equivalencies.
| JP Cup | UK / AU Cup | US Cup | EU Cup | Overbust − Underbust (cm) |
|---|---|---|---|---|
| AAA | — | — | — | under 7.5 cm |
| AA | AA | AA | AA | 7.5–10 cm |
| A | A | A | A | 10–12.5 cm |
| B | B | B | B | 12.5–15 cm |
| C | C | C | C | 15–17.5 cm |
| D | D | D | D | 17.5–20 cm |
| E | DD | DD | E | 20–22.5 cm |
| F | E | DDD | F | 22.5–25 cm |
| G | F | DDDD/G | G | 25–27.5 cm |
| H | FF | G/H | H | 27.5–30 cm |
Many shoppers assume JP E cup is the same as UK E cup. It is not. JP E equals UK DD — not UK E. The JP cup system starts from a smaller base (AAA), meaning each JP letter represents a smaller cup than the same letter in the UK system above C cup. JP E cup (20–22.5 cm difference) equals UK DD cup (22–23 cm). JP F cup equals UK E cup. This shift causes consistent ordering errors when Japanese shoppers buy from UK brands like Bravissimo or Panache.
What Are Sister Sizes in Japanese Bras?
Sister sizes in the JP system work identically to EU sizing — bands step in 5 cm, and cup letters shift by one step when the band changes.
The sister size rule
- Smaller band, larger cup: If your JP 75C band rides up, try JP 70D. Same volume, tighter band.
- Larger band, smaller cup: If your JP 75C band digs in, try JP 80B. Same volume, looser band.
| JP Size | Band Feel | Cup Volume | When to Try It |
|---|---|---|---|
| JP 70D | Tighter | Same | Your JP 75C band rides up or feels loose |
| JP 75C | Standard | Same | Your primary size |
| JP 80B | Looser | Same | Your JP 75C band digs in or feels tight |
Japanese bra brands excel at precise cup grading for Asian breast shapes
Japanese Bra Brand Sizing Differences
Japanese brands follow JIS L 4006 closely, but construction and cup grading vary between labels.
Wacoal Japan
Japan’s largest and most scientifically rigorous lingerie brand. Wacoal’s sizing is the Japanese market reference — their cup grading follows JIS L 4006 precisely and their fit research underpins the entire industry. Stocks JP 60–90 bands and AAA–H cups across their main ranges.
Fit: True to JP size. Wacoal is the calibration brand for Japanese sizing — use it as your benchmark when testing other JP labels. Their cups are graded for medium-projection breast shapes.
Triumph Japan
German brand’s Japanese subsidiary — uses JP sizing on Japanese-market labels, which differs from Triumph’s EU sizing in Europe. Triumph Japan stocks JP 65–90 bands and AA–G cups. Known for precise engineering and consistent sizing.
Fit: True to JP size. Note that Triumph Japan and Triumph Europe use different sizing systems — do not use European Triumph size guides when shopping Triumph Japan labels.
Peach John JP
Popular Japanese lingerie brand focused on fashion-forward styles. Uses JP sizing with bands 65–85 and cups AA–F. Peach John cups tend to run slightly generous — particularly in their push-up and padded styles.
Fit: Cups run slightly generous in padded styles — size down one cup letter in Peach John push-up styles compared to your Wacoal size. Wire-free styles are true to JP size.
Uniqlo JP
Uniqlo’s bra range (primarily wireless and Airism styles) uses JP sizing but follows a simplified band range of 65–80 and cups A–D. Uniqlo bands run firm — bands tend to feel one size smaller than the label.
Fit: Bands run firm — size up one band from your JP size if between sizes. Cups are true to JP standard in wire-free styles. Limited range above D cup.
Felissimo JP
Japanese mail-order brand known for its subscription bra service and extended size range. Felissimo uses JP sizing and stocks bands 65–100 and cups AA–H — one of the widest ranges in the Japanese market.
Fit: True to JP size. Felissimo’s extended cup range (through H) makes it the go-to Japanese brand for larger cup sizes that Wacoal and Uniqlo don’t stock.
Wacoal (International / US line)
Wacoal sells in the US, UK, and Australia using Western sizing — US cup letters (not JP letters). A JP 75E Wacoal Japan shopper would be a US 34DD Wacoal US shopper. The brands share parent company but use different sizing systems.
Conversion tip: JP 75E → US 34DD → UK 34DD → AU 12DD. Wacoal US cups run true — the conversion is direct, no additional brand offset needed.
Victoria’s Secret US (buying from Japan)
Uses US sizing. Available online in Japan. Band numbers convert via cm: JP 75 = US 34. Cup letters diverge: JP D = US D, JP E = US DD, JP F = US DDD. VS does not stock above US DDD (= JP F), limiting options for JP G and H cup shoppers.
Conversion tip: If you’re JP 75F, look for US 34DDD. JP E → US DD. JP F → US DDD. VS bands run small — size up one US band from your JP equivalent if borderline.
Bravissimo UK (buying from Japan)
UK D+ specialist. UK cup letters are one step behind JP above D: JP E = UK DD, JP F = UK E, JP G = UK F. Band: JP 75 = UK 34, JP 80 = UK 36. Ships internationally including Japan.
Conversion tip: JP 75F → UK 34E at Bravissimo. Keep band equivalent, drop one cup letter when converting JP to UK above D cup. Bravissimo’s range starts where most JP retailers stop.
Signs Your Japanese Bra Size Is Wrong
Band size problems
- Band rides up at the back: band too big. Try JP 5 cm down, one cup up (e.g., JP 80B → 75C).
- Band digs in or leaves marks: band too small. Try JP 5 cm up, one cup down (e.g., JP 75C → 80B).
- Band pulls forward when arms are raised: band too loose. Tighten hooks or go down 5 cm.
Cup size problems
- Spillover at top or sides: cup too small. Size up one JP cup letter (JP 75C → 75D).
- Gaping or wrinkling: cup too big. Size down one letter (JP 75C → 75B).
- Underwire on breast tissue not flat on ribcage: cup too small. Size up immediately.
- Centre gore not flat against sternum: cup too small or wire width wrong for your breast spacing.
Wacoal Japan’s published consumer research suggests the majority of Japanese women wearing the wrong bra size are in cups that are too small, particularly at D cup and above. The cultural reluctance to select what might be perceived as a “large” cup size — combined with limited retail stock above E cup at mass-market stores — causes many Japanese women to wear E or F cup when their true JP size is G or H. Measuring and using the JP cup chart directly removes this bias.
Why Japanese Bra Sizing Confuses Everyone
The cup-letter shift above D
The most significant JP conversion error arises because the JP cup alphabet starts from AAA — a cup smaller than exists in most other systems. This means each JP letter above C represents slightly less volume than the same letter in the UK, EU, or US system. JP E (20–22.5 cm) equals UK DD (22–23 cm) — not UK E. JP F equals UK E. When Japanese shoppers convert their size to Western sizing without knowing this shift, they consistently order one cup too large from UK and EU brands.
The Triumph Japan / Triumph Europe problem
Triumph manufactures for both the Japanese market (using JP sizing) and the European market (using EU sizing) under the same brand name. A JP Triumph 75C and an EU Triumph 75C are the same band but different cups — JP C covers 15–17.5 cm difference, EU C covers 14–15 cm difference. They are close but not identical. Japanese shoppers purchasing from European Triumph online must convert their JP cup using the international conversion table, not the Triumph brand chart, which is written for European customers.
The three-label problem for Japanese shoppers
- 🇯🇵 Wacoal Japan: JP 75E
- 🇬🇧 Bravissimo (UK): UK 34DD — band converts, cup drops one letter
- 🇺🇸 Victoria’s Secret (US): US 34DD — band converts, same cup as UK
- 🇩🇪 Triumph (EU): EU 75E — same band number, same letter but slightly different volume
- 🇦🇺 Berlei (Australia): AU 10DD — dress-size band, same cup as UK
Our approach treats JP band sizing as identical to EU band sizing — both round underbust cm to the nearest 5. For the cup, we use the JP-specific 2.5 cm intervals starting from AAA, then apply the JP-to-UK cup conversion table (JP E → UK DD, JP F → UK E, JP G → UK F) and JP-to-EU cup mapping (JP E → EU E, JP F → EU F) to produce accurate international conversions. This is the only approach that correctly handles the JP cup offset without rounding errors.
Shopping International Brands as a Japanese Shopper
Buying from UK retailers
JP band equals UK band: JP 75 = UK 34, JP 80 = UK 36. For cups through D: JP A = UK A, JP D = UK D — identical. Above D: JP E = UK DD, JP F = UK E, JP G = UK F, JP H = UK FF. So JP 75F becomes UK 34E at Bravissimo, Panache, or Marks & Spencer. The one-letter drop above D is the critical rule.
Buying from US retailers
JP band to US band via cm: JP 75 (68–72 cm) = US 34, JP 80 = US 36. Cups: JP A–D = US A–D (identical). Above D: JP E = US DD, JP F = US DDD, JP G = US DDDD. So JP 75F = US 34DDD at Victoria’s Secret, ThirdLove, or Wacoal US. US bands run small — size up one if borderline.
Buying from EU retailers
JP and EU bands are identical: JP 75 = EU 75. Cup letters are approximately aligned but use different grading intervals: JP C (15–17.5 cm) is slightly larger than EU C (14–15 cm). For practical shopping above C cup: JP D ≈ EU D, JP E = EU E, JP F = EU F, JP G = EU G. Triumph and Hunkemöller use EU sizing. French brands add 15 to EU band: JP 75 = EU 75 = FR 90.
Buying from Australian retailers
Convert band: JP 75 = AU 10, JP 80 = AU 12, JP 85 = AU 14. Convert cup: same shift as UK — JP E = AU DD, JP F = AU E, JP G = AU F. So JP 75F = AU 10E at Berlei or Bras N Things.
When shopping from Rakuten Global Market or Japanese brand international sites (Wacoal global, Triumph Japan international), always check whether the product listing uses JP sizing or the brand’s Western sizing. Some brands switch to EU or US sizing on international-market pages while retaining JP sizing on their domestic Japanese pages. The product page’s size guide is more reliable than the size filter for confirming which system applies to a specific item.
Recommended Bras for Japanese Sizing
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- JP bands 65–90, cups AA–F
- Wire-free all-day comfort
- Wacoal Japan, Triumph JP styles
- Smooth under any fabric
- JP bands 65–85, cups A–E
- Triumph JP, Uniqlo, Peach John
- JP E = UK DD, JP F = UK E
- Bands 34–42, cups DD–GG (UK)
- Bravissimo, Panache, Freya styles
- JP bands 65–85, cups A–E
- High impact, encapsulation design
- Wacoal Sports, Triumph Active
Frequently Asked Questions
Japanese bra sizing uses centimetre-based band numbers (60, 65, 70, 75, 80, 85, 90, 95) and a unique single-letter cup sequence (AAA, AA, A, B, C, D, E, F, G, H) with no doubled letters. Band is your underbust cm rounded to the nearest 5. Cup is the difference between overbust and underbust in 2.5 cm steps: 15–17.5 cm = C, 17.5–20 cm = D, 20–22.5 cm = E. The system is codified under JIS L 4006 and used by Wacoal Japan, Triumph Japan, Peach John, and Uniqlo.
No. JP E cup equals UK DD cup — not UK E. The JP system starts from AAA (smaller than AA in other systems), which means each JP letter above C represents slightly less volume than the same letter in the UK system. JP E (20–22.5 cm) corresponds to UK DD (22–23 cm). JP F equals UK E. This one-letter shift above D is the most critical JP-to-UK conversion rule. Japanese shoppers buying from Bravissimo should drop one cup letter: JP 75E becomes UK 34DD, not 34E.
JP and EU bands are identical — both round underbust cm to the nearest 5, giving the same band number. JP 75 = EU 75. The cup systems are different. EU cups use 2 cm increments; JP cups use 2.5 cm increments starting from AAA. Through C cup, the letters are close but not exactly equivalent. Above D: JP D ≈ EU D, JP E = EU E approximately, JP F = EU F approximately. For practical shopping, the cup letters match approximately from D upward despite the different interval sizes.
Wacoal Japan’s published internal sales data identifies JP 75B and JP 70B as the most commonly purchased sizes in Japan, reflecting the smaller average underbust measurement and cup size among Japanese women compared to Western averages. However, Wacoal’s own consumer research suggests the average correctly measured size among Japanese women is closer to JP 75C, with many women wearing B cup when their true cup is C or D. As with other markets, sales data underrepresents larger cups due to limited retail availability above E cup at mainstream stores.
JP band equals UK band: JP 70 = UK 32, JP 75 = UK 34, JP 80 = UK 36. For cups through D: JP A = UK A, JP D = UK D — identical. Above D: JP E = UK DD, JP F = UK E, JP G = UK F, JP H = UK FF. So JP 75F becomes UK 34E at Bravissimo or Panache. The one-letter drop above D is the critical rule — keeping the same letter results in ordering one cup too large from UK brands.
Yes. JP AAA is the smallest cup in the Japanese system, representing an overbust-minus-underbust difference of less than 7.5 cm. It has no direct equivalent in UK, US, or EU systems, which typically start at AA or A cup. AAA cup is stocked by Wacoal Japan, Triumph Japan, and Felissimo, and is designed for petite frames with very little breast projection. If you measure less than 7.5 cm difference, JP AAA is your size — it does not correspond to a named cup in Western sizing systems.
Sister sizes in the JP system step in 5 cm increments for the band and one letter for the cup. From JP 75C, the sister sizes are JP 70D (tighter band, same cup volume) and JP 80B (looser band, same cup volume). Sister sizes are particularly useful when shopping Wacoal Japan or Triumph JP where specific sizes sell out quickly in the AAA–C range, which is the most popular segment of the Japanese market.
Measure your underbust snugly in centimetres and round to the nearest 5: 68–72 cm = JP 70, 73–77 cm = JP 75, 78–82 cm = JP 80. Measure your overbust loosely at the fullest point. Subtract underbust from overbust using 2.5 cm steps: 10–12.5 cm = A, 12.5–15 cm = B, 15–17.5 cm = C, 17.5–20 cm = D, 20–22.5 cm = E. Wacoal Japan recommends measuring without any bra for the most accurate result. Our Japan calculator accepts centimetres directly.
Every six months at minimum, or after any weight change of 3 kg or more, pregnancy, breastfeeding, or notable changes in how your current bras fit. Wacoal Japan’s research specifically notes that Japanese women experience measurable breast size changes with age and hormonal cycles — their published data recommends professional re-fitting annually and home remeasurement every six months as standard practice.
JP bands step in 5 cm, so boundary measurements are common. If your underbust is exactly 77 cm — the boundary between JP 75 and JP 80 — try JP 75 first. Wacoal Japan’s fitting guidance recommends starting with the smaller band, as JP bands use an elastane blend that relaxes with wear. A JP 75 that feels slightly firm when new will typically settle to a comfortable fit within a week. If it still feels tight when breathing deeply after regular wear, try JP 80.
Wacoal Japan stocks through JP H cup in selected styles, with bands up to JP 95. Triumph Japan extends to approximately G cup in their full range. Felissimo stocks the widest JP range — bands 65–100 and cups AA–H. For sizes beyond H cup in JP terms, the equivalent in UK sizing is FF or GG cup, which is readily available from UK specialists like Bravissimo and Fantasie who ship internationally to Japan.
No. Triumph Japan uses JP sizing (cm bands 60–95, cup letters AAA–G following JIS L 4006). Triumph Europe uses EU sizing (cm bands 65–105, cup letters A–H following the EU grading). A Triumph Japan 75C and a Triumph Europe 75C have the same band but different cup volumes — JP C covers 15–17.5 cm difference, EU C covers 14–15 cm difference. When buying Triumph internationally, always verify which sizing system applies to the specific product line before converting.
Korean bra sizing (KR) follows almost the same system as Japanese sizing — cm-based bands rounded to nearest 5, and the same single-letter cup sequence (AAA, AA, A, B, C, D, E, F, G, H) with 2.5 cm intervals. In practice, JP and KR sizes are directly interchangeable for most sizes through H cup. Minor differences exist in the AAA and AA cup definitions between brands, but from A cup upward, JP and KR sizing are functionally identical. Korean brands like Vivien and Wacoal Korea follow the same standard as Wacoal Japan.
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