Popular
START HEREBra size calculator
Two simple measurements. A size that’s a better starting point for you.
Calculate my size
A little knowledge. A better fit.
Calculate Your Bra Size,
Beautifully Simple.
Enter two tape measurements to get an estimated bra size.
Then check sister sizes, international labels, and fit.
Free, private, no sign-up.
Free to use. No sign-up. Just a better fit.
Made for every body
Simple, thoughtful tools
Your measurements stay private
Comfort over everything
START HERE
Find your bra size.
Two simple measurements. A size that’s a better starting point for you. Free to use, no sign-up, and your measurements never leave your browser.
YOUR FIT TOOLKIT
Good fit starts here.
Four free tools: calculator, sister sizes, size converter, fit checker.
Sister size finder
Love the cup, not the band? Discover sizes with a similar cup volume.
Find sister sizesBra size converter
UK, US, or EU? Make sense of international bra size labels.
Convert my sizeBra fit checker
Small details, big comfort. Find out if your bra is really fitting you.
Check my fitA LITTLE BRA KNOW-HOW
There’s more to a bra
than a number and a letter.
How the band, cups, centre gore, and straps each work, and what each one should feel like on your body.
Understand your size
Find your comfort
Get to know your bra
THE FIT EDIT
Little reads. Better fits.
THE BASICS · 3 MIN READ
How to measure your bra size
A measuring tape, a few minutes, and a fresh start. The one guide to read first.
FIT & COMFORT · 4 MIN READ
What a good bra fit feels like
The little signs that your bra is working with you.
SIZE KNOW-HOW · 3 MIN READ
Sister sizes, simply explained
Why more than one size might feel like your size.
HOW IT WORKS
Calculate bra size in three steps.
You need a soft measuring tape and two numbers: a snug underbust and a standing bust, in inches or centimeters. The calculator estimates your band from the underbust and your cup from the difference between the two, and shows the matching US and EU sizes.
Measure
Snug underbust beneath your breasts, loose bust around the fullest part. Inches or centimeters, your call.
Calculate
Band from the underbust, cup size from the bust-to-underbust difference, with US and EU equivalents included.
Check the fit
Level band, smooth cups, straps that stay put. Comfort has the final say.
Frequently asked questions
How do I calculate my bra size?
Measure your snug underbust and your standing bust with a soft tape, then enter both numbers in the calculator above. It rounds your underbust to a nearby even band and estimates your cup from the difference. For example, 32 under and 36 bust is roughly a 32D.
How do I calculate my cup size?
Subtract your underbust from your bust measurement. Each inch of difference is roughly one cup step: 1 inch about an A, 2 inches a B, 3 inches a C, 4 inches a D, and so on.
How do I know my cup size without measuring?
Fit clues help: spilling out of the cups usually means going up a cup, while gaping can mean going down a cup or trying a different cup shape. Two tape measurements take about a minute and give a more reliable starting point.
Does the calculator work in inches?
Yes. It is a bra size calculator in inches and centimeters: pick your unit, enter both measurements, and it handles the conversion either way.
What are sister sizes?
Sister sizes hold roughly the same cup volume on different bands: down one band and up one cup, or the reverse. For example, 34C sisters are 32D and 36B. Try them when the cups fit but the band does not.
Why does my band ride up?
A riding band is usually too loose to anchor the bra, which pushes support onto the straps. Try a firmer band: going down one band and up one cup keeps roughly the same cup volume.
What if the cups gape?
Gaping can mean the cup is too big, or the shape does not suit you. Try the same size in a different cut before sizing down, since shape mismatches gape even at the right volume.
How often should I remeasure?
There is no fixed schedule. Re-measure after significant weight change, during or after pregnancy, or whenever bras that used to fit stop feeling comfortable.
Do US and UK sizes match?
Bands usually match and cups match up to DD. Beyond that they diverge: a UK E is generally a US DDD. Check the brand chart and convert before ordering across systems.
Is my information saved anywhere?
No. Every calculation runs in your browser. There are no accounts, no sign-ups, and nothing is sent to a server.
Every body deserves a feel-good fit.
Comfort is the final check: trust how a bra feels through the day.