Convert bra sizes across US, UK, EU, AU/NZ, FR/ES, IT, and JP charts, then compare sister sizes and same-band cup changes before you buy.
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Bra size converter with sister-size and fit-adjustment guidance Convert bra sizes across US, UK, EU, AU/NZ, FR/ES, IT, and JP labels, then see what to try next if the band is too tight, too loose, or the cup volume is the real problem.
Quick starting sizes
Load a familiar size to compare international labels and the most common next sizes to test.
What are you trying to solve?
Important conversion cautions
UK and US labels often look identical through D, then diverge as cup progression changes. That is why the converter treats the full band-and-cup size as one unit instead of asking you to translate the cup letter on its own.
Many shoppers also run into bras sold in a brand’s home sizing even on an overseas site. Use the converted row as a starting point, then check the brand’s own chart before trusting the listing label blindly.
Bra-size conversion
US 32C
International chart equivalents plus the nearest same-system sizes to try when the fit issue is the band, the cup, or both.
Sister size down
30D
Sister size up
34B
Same band, cup down
32B
Same band, cup up
32D
Systems shown
7
If you are only converting labels between countries Use 32C as the anchor, then compare the international row rather than converting the band and cup separately.
Brand fit still varies, so the converted row is a shopping starting point rather than a guaranteed match.
International bra-size sheet
System
Equivalent size
Notes
US
32C
Original selected system.
UK
32C
Chart equivalent only. Confirm against the brand’s own sizing guide before buying.
EU
70C
Chart equivalent only. Confirm against the brand’s own sizing guide before buying.
AU/NZ
10C
Chart equivalent only. Confirm against the brand’s own sizing guide before buying.
FR/ES
85C
Chart equivalent only. Confirm against the brand’s own sizing guide before buying.
IT
2C
Chart equivalent only. Confirm against the brand’s own sizing guide before buying.
JP
70C
Chart equivalent only. Confirm against the brand’s own sizing guide before buying.
How to use the output well
If the band feels wrong but the cups feel close, start with the sister-size cards. If the band feels right but the cups spill or gape, test the same-band cup change before blaming the conversion itself.
The converted row is strongest when you already know one size that fits reasonably well and need the likely label in another market. If you do not know your starting size yet, the measurement-based bra size calculator is the better first step.
Bra size converter: international bra chart, sister sizes, and fit-adjustment guide
A bra size converter is most useful when you already know a size that fits reasonably well and need the likely label in another market. The strongest bra size conversion tools do more than translate US, UK, EU, AU/NZ, FR/ES, IT, and JP labels. They also show sister sizes, explain when UK and US cup letters stop matching cleanly, and help you decide whether the band, the cup, or the conversion itself is the real issue.
Why bra sizes do not convert perfectly
Bra size conversion looks simple until two labels that should be equivalent still fit differently on the body. That happens because conversion charts only translate labels. They do not standardise wire width, cup depth, strap placement, elastic tension, or how aggressively a brand grades between sizes.
That is why this bra size converter should be treated as a starting map. It can narrow your likely label across countries, but it cannot promise that a UK 34DD, a US 34DD, and an EU 75E will feel identical across every brand or style.
Why UK and US cup letters often cause confusion
Many shoppers search for a UK to US bra size converter because the early part of the cup sequence looks similar and then diverges. Through D, UK and US labels often appear to match. After that point, UK sizing typically uses a different double-letter progression, which is where a lot of shopping mistakes start.
That is also why converting the cup letter on its own is risky. The full band-and-cup combination needs to stay together. A useful international bra size chart converts the entire size row at once instead of pretending the cup label is globally universal.
What sister sizes actually solve
Sister sizes are nearby sizes that keep roughly the same cup volume while changing band tension. If the band feels too tight but the cup volume feels close, going up one band and down one cup is usually the first test. If the band feels too loose but the cups feel close, going down one band and up one cup is the usual move.
That is only one kind of fit fix, though. Sister sizes are meant for band problems with roughly correct cup volume. They are not the cleanest answer when the band feels fine and the cups gape or cut in, because that usually calls for a same-band cup change instead.
When to sister-size and when to change only the cup
Competitor pages often stop at a sister-size chart, but real shopping decisions need one more step. If the band is stable and comfortable while the cups spill, cut in, or the gore will not sit flat, the next test is usually a larger cup on the same band. If the band feels right but the cups gape, wrinkle, or sit empty at the top, the next test is often a smaller cup on the same band.
That is why this page now separates band-too-tight and band-too-loose guidance from cups-feel-small and cups-gap guidance. The difference matters because the right size adjustment depends on which part of the fit is wrong.
Worked example: US 32C conversion
A US 32C generally converts to UK 32C, EU 70C, AU/NZ 10C, FR/ES 85C, IT 2C, and JP 70C on a standard international chart. If the band feels too tight but the cup volume seems close, the usual sister size up is 34B. If the band feels too loose but the cups feel close, the usual sister size down is 30D.
If the band feels right but the cups are too small, the more useful next test is 32D rather than a sister size. If the band feels right but the cups gape, 32B is often the cleaner next size to try. That band-versus-cup distinction is the practical step many chart-only pages leave out.
Worked example: UK 34DD conversion
A UK 34DD generally converts to US 34DD, EU 75E, AU/NZ 12DD, FR/ES 90E, IT 3E, and JP 75E in a standard chart. If the band feels too tight, the nearby sister size is 36D. If the band feels too loose, the nearby sister size is 32E.
This example is useful because it shows how UK cup progression matters. A shopper who converts only the band and forgets the system-specific cup progression can end up in the wrong cup sequence quickly, especially once double letters and extended ranges enter the picture.
Why brand-native sizing still matters
A retailer may sell internationally while still grading bras in the brand's home sizing system. That means a bra sold on a US-facing site may still behave more like a UK-sized product, or a European label may follow the brand's own cup progression rather than the generic chart the shopper expects.
The safest workflow is to use a bra size converter to get into the right size neighbourhood, then compare the result against the brand's own chart before ordering. If a listing looks inconsistent, treat the brand guide as the stronger authority over a third-party marketplace label.
When to use a bra size converter versus a bra size calculator
A converter starts from a size you already know and translates it across other markets. A bra size calculator starts from body measurements and estimates the starting size itself. If you do not know a size that fits well yet, the calculator is the better first tool. If you already know a baseline size and need to shop a foreign size chart, the converter is the right tool.
Many shoppers need both. First use a calculator to estimate the starting size from measurements. Then use a converter to compare the likely UK, US, EU, AU/NZ, FR/ES, IT, or JP label when shopping cross-border.
Frequently asked questions
Is a bra size converter the same as a bra size calculator?
No. A bra size converter translates a size you already know across other systems. A bra size calculator starts from your underbust and bust measurements and estimates the starting size itself. If you do not know your baseline fit yet, the calculator is the better first step.
How do I convert bra size from US to UK?
Convert the full band-and-cup size together, not the cup letter alone. A US to UK bra size converter should account for the different cup progression after D and preserve the band as part of the same size row.
Why do UK and US bra cup sizes stop matching cleanly after D?
Because the two systems use different cup-letter progressions once you move beyond the early alphabet. That is why labels that look similar through D can diverge later, and why converting only the cup letter is unreliable.
What is a sister size in bras?
A sister size is a nearby size with roughly the same cup volume but a different band. Going up one band and down one cup, or down one band and up one cup, preserves approximate cup volume while changing band tension.
When should I use a sister size instead of changing the cup only?
Use a sister size when the cups feel close but the band is too tight or too loose. If the band feels fine and the cups alone are the problem, a same-band cup change is usually the cleaner next test.
Why can two bras with the same converted size still fit differently?
Because conversion charts only translate labels. Real fit still depends on cup shape, wire width, elastic tension, strap placement, padding, fabric stretch, and how the brand grades that particular style.
Should I trust the converter or the brand's own chart?
Use the converter to get into the right size neighbourhood, then trust the brand chart for the final purchase decision. The brand chart is the stronger source when there is a conflict.
Why do cups sometimes gape even when the converted size looks right?
Cup gaping can come from cup volume, but it can also come from shape mismatch, tall cups, shallow cups, strap placement, or a band that is not anchoring the bra correctly. A converted size can still be the right label row while the style itself is the wrong shape.
