Bra size calculator
Enter your underbust and bust to see your bra size, your sister sizes, and your size in the labels of 159 brands. Nothing you type leaves this page.
Your size
Band from your underbust, to the nearest even inch. Cup from how much bigger your bust is: one US cup letter per inch, counted from halfway between your underbust and the band.
Sister sizes
The same cup volume on a band one size tighter or looser. Worth trying when your size is sold out, or when the band feels too tight (go up) or too loose (go down).
None to show for a size past the ends of our range.
In other countries' sizes
| Country | Size |
|---|
None to show for a size past the ends of our range.
In letter sizes
The usual letter, from the brand letter charts Measured Size has. A brand's own chart comes first, below.
In each brand's own labels
Measured Size reads the listing you're on: your size in its labels, whether it's in stock, and a sister size when it isn't. Free, for Chrome on a computer.
Add Measured Size to ChromeHow to measure
A soft tape measure is all you need. Stand straight with your arms down, and measure against your skin or over an unpadded bra.
Underbust: the band does most of a bra's supporting, so this one is snug. Take the tape firmly around your ribcage, just under your bust, after breathing out.
Bust: around the fullest part, with the tape lying flat and not pressing in.
Bodies change. Measure again after a pregnancy, a change in weight, or when a bra that fitted stops fitting.
Questions
- Why is my size different in different brands?
- Your size from your measurements is the same everywhere. Brands label it differently. Some use UK cup letters, where a US DDD is an E. Some sell letter sizes such as S, M and L, and their charts don't agree on which band and cup sizes each letter covers. Some don't make every band. Measured Size translates your size into each brand's own labels, and says so when a brand doesn't carry it.
- What is a sister size?
- The size one band up with one cup letter smaller, or one band down with one cup letter bigger. It holds the same cup volume on a looser or tighter band. Try one when your size is sold out, or when a band feels too tight (go up a band) or too loose (go down a band).
- Inches or centimetres?
- Either. Pick one with the switch above the boxes and type what the tape says, decimals included. Centimetres are turned into inches, to the hundredth, before anything is worked out, so the two give the same size.
- Does this page keep my measurements?
- Only if you tick "Remember my measurements", and then only in your browser on this phone or computer, until you choose "Forget my measurements". Your size is worked out on this page. Nothing you type is sent anywhere or put in the page's address, and the page loads nothing from anywhere else.
- Can I keep it on my phone?
- Yes. Add this page to your home screen and it opens like an app, and works with no connection. On Android, use the Add button under your results, or your browser's menu. On iPhone, tap Share in Safari (on iOS 26 and later, it is in the ⋯ menu), then Add to Home Screen.