Bra Calculators
Skip the guesswork. Our free calculators help you find your true bra size, convert sizes between countries, discover your sister sizes, and pick the right sports bra fit — all in a few clicks.
Bra Size Calculator by Country
Bra sizing isn't universal — a US 34B isn't labeled the same way in the UK, EU, Australia, or Asia. Enter your measurements or your home-country size and instantly convert it to US, UK, EU, FR, IT, AU, and JP sizing standards.
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Sister Bra Size Calculator
If your usual size runs out of stock or never quite feels right, a sister size can save the day. This tool instantly finds bra sizes with the same cup volume but a looser or snugger band, so you always have a backup fit.
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Sports Bra Calculator
Sports bras fit differently than everyday bras since they rely on compression and encapsulation for support. Answer a few quick questions about your activity level and measurements to find the ideal sports bra size and support type.
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Band Size Calculator
The band does most of the heavy lifting when it comes to support. Use this calculator to measure your rib cage accurately and get a precise band size recommendation, with tips for choosing between two close sizes.
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Cup Size Calculator
Cup size is based on the difference between your bust and band measurements — not a fixed letter. This calculator walks you through both measurements to give you an accurate cup size, from AA all the way to K.
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Bra Size Change Calculator
Weight changes, pregnancy, and hormonal shifts can all affect bra size over time. Enter your previous and current measurements to see how your size has shifted and get style suggestions for your new fit.
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Breast Size Calculator
Get a fuller picture of your proportions by calculating your breast size based on bust, band, and cup measurements together. This tool helps translate your numbers into an easy-to-understand size description for shopping online.
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Teen Bra Size Calculator
Designed with parents and teens in mind, this gentle, easy-to-follow calculator helps younger people find a comfortable, well-fitted first bra using simple measurement steps and beginner-friendly size recommendations.
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Plus Size Bra Calculator
Fuller busts and larger bands need their own fit approach. This calculator accounts for extended band and cup ranges to help you find supportive, well-fitting plus size bras without the trial and error.
Read MoreNot sure which calculator to start with? If this is your first time checking your size, start with the Band Size and Cup Size calculators, then use the Sister Size tool to explore alternate fits.