Japanese sizing drops the padding entirely — where Europe adds about 16cm to your underbust for the band number, Japan mostly just uses the raw measurement. A Japanese band size is close to your actual underbust in centimeters rounded to the nearest 5, with cup letters generally matching the EU-style scale.
Japanese sizing drops the padding entirely — where Europe adds about 16cm to your underbust for the band number, Japan mostly just uses the raw measurement. A Japanese band size is close to your actual underbust in centimeters rounded to the nearest 5, with cup letters generally matching the EU-style scale.
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How Japan Sizing Actually Works
A Japanese band size is close to your actual underbust in centimeters rounded to the nearest 5, with cup letters generally matching the EU-style scale.
This makes Japanese sizing numerically the most different from US/UK sizing of any system on this page — always run the conversion rather than guessing.
Convert Your Size
Use the calculator above to see your size across all 7 systems this site supports, Japan included. If you already know your size in another system, enter it into the Global Bra Size Converter instead of doing the math by hand.
Getting an Accurate Starting Point
No conversion is more accurate than the measurement it’s based on — How to Measure covers the exact technique this calculator assumes, and the Sister Size Calculator is worth trying if your first result doesn’t feel quite right.
A Worked Example for Japan
Say your underbust measures 36 inches and your bust measures 40 inches — a US 36D. Converted to Japan’s system, that becomes roughly 90cm D using the formula above. Run your own numbers through the calculator on this page rather than eyeballing the conversion — small rounding differences near a size boundary can shift the result by a full cup letter.
Shopping Locally vs. Importing in Japan
Japanese department stores are known for detailed, unhurried fitting appointments, and staff will typically re-measure you on the spot rather than relying on a self-reported size.
Common Sizing Mistakes Shoppers Make in Japan
A frequent mistake among shoppers converting into Japan’s system is applying the EU +16cm padding formula instead of Japan’s raw-underbust approach, which overstates the band by a meaningful margin.
Shoppers also sometimes apply Japan’s raw-cm band formula to Korean sizing, when the two are close but not always identically rounded.
A Note on Retail Fitting in Japan
Japanese department store fittings are famously thorough and unhurried, with staff typically re-measuring rather than trusting a self-reported size.
Why Japan’s System Looks Different at First Glance
Japan’s centimeter-based band measurement without the extra padding used in the EU formula can make a Japanese size look smaller on paper than the equivalent Western size — it’s a different reference point, not a smaller actual fit.
A Sizing System Built Around Precision Measurement
Japanese retail culture places a strong emphasis on precise, professionally-guided measurement, and department store fitting services remain a common and trusted resource for finding an accurate size rather than relying solely on self-measurement.
Limited Overlap With Western Extended Sizing
Historically, Japanese mainstream retail has offered a narrower cup-letter range than some Western markets, meaning shoppers at either end of the size spectrum sometimes need to look at import options or specialty retailers for full coverage.
Seasonal Product Cycles Are Common
Japanese retailers often rotate seasonal collections more frequently than some Western markets, which can mean a specific size or style available one season may not be restocked identically the next — worth buying when you find the right fit.
FAQ
Japan doesn't add the ~16cm padding that EU sizing does — it stays close to the raw underbust measurement.
Broadly yes, though always confirm with a specific brand's own chart.
Yes — both follow a similar raw-underbust-in-cm approach.
A converter gets you close, but cut and construction still vary by brand — treat the converted number as your starting point for trying on, not a guarantee.
Yes — conversions get less reliable at the extremes of any scale, since brands often adjust proportions rather than just scaling a size up or down uniformly.
It can add cost and delivery time, and in some cases customs duties — factor this in especially for a size you're not fully confident about, since returns get more expensive across borders.
After — get your baseline size from the calculator, then check that exact product's own chart, since retailer-wide conversions are a starting point, not a guarantee for every individual style.
Most markets have at least some domestic labels alongside international brands, but sizing conventions typically follow whichever system that specific brand was designed under, not necessarily the country it's sold in.
The two systems are similar in using centimeter-based bands, but always check the specific chart — similar isn't identical, and small differences do exist.
