Cherry SizeFind your true bra size
Two measurements, ten seconds. Your exact band and cup in every sizing system — computed right here on your device, never uploaded.
Snug tape right under your bust, parallel to the floor.
Loose tape over the fullest point, wearing a non-padded bra.
Your bra size
34C US
Your sister sizes
Brands cut differently — the same body is a 75C at H&M and a 70D at Nike. The Cherry Size app translates your measurements into 632 brands.
See my size by brandHow the bra size calculator works
About 8 in 10 women wear the wrong bra size — usually a band too big and a cup too small. Getting it right takes two numbers.
Measure your underbust
Wrap a soft tape right under your bust, snug and level. Exhale normally and note the number in centimetres.
Measure your bust
Measure around the fullest part of your bust in a non-padded bra, tape resting lightly — not compressing.
Read your size — everywhere
The difference between the two sets your cup; the underbust sets your band. We convert it into every major sizing system instantly.
Same body, different label at every brand
Sizing charts are only the start: real bras run tight or generous depending on the brand. Cherry Size for iPhone learns how each label cuts and shows the size to actually try on — across 632 brands, updated with your fit feedback.
Bra size questions, answered
How do I calculate my bra size?
Measure your underbust (snug, right under the bust) and your bust (at the fullest point). Your underbust rounded to the nearest 5 cm gives your band size — for example, 74 cm rounds to a 75 band. The difference between bust and underbust gives your cup: roughly every 2.5 cm is one cup letter, with about 12–13 cm corresponding to a B cup. The calculator above does both steps for you and converts the result into EU, UK, US, FR and IT sizing.
What is a sister size?
Sister sizes share the same cup volume with a different band length. Going one band down means going one cup letter up (75C → 70D), and one band up means one cup down (75C → 80B). They matter because a style that feels too tight or too loose in the band can often fit perfectly in a sister size — and because some brands simply don't make every size.
Why do I wear different sizes in different brands?
There is no single worldwide standard: a 75C in a European brand corresponds to a 34C in UK/US sizing, and on top of that each brand cuts its own patterns — some run a full band tight, others a cup generous. That's why fitting experts recommend knowing your measured size plus your sister sizes, and adjusting per brand. The Cherry Size app automates exactly that for 632 brands.
How tight should the band be?
The band does about 80% of the supporting work, so it should be snug: level all the way around, two fingers fitting underneath, and it shouldn't ride up when you raise your arms. If it rides up or you're on the loosest hook from day one, the band is too big — try the sister size with a smaller band.
How often should I re-measure?
Every 6–12 months, and after anything that changes your body: weight change of a few kilos, pregnancy, breastfeeding, hormonal treatment, or a new sport routine. Bra size isn't fixed — most fit problems come from wearing the size that was right two years ago.
Is this calculator really private?
Yes. The calculation runs entirely in your browser — your measurements are never sent to a server, stored, or shared. There's no account, no cookies used for tracking, and no photos involved. The Cherry Size iPhone app works the same way: everything stays on your device.
Your size, everywhere you shop
Cherry Size keeps your measurements on your iPhone, translates them into 632 brands, tracks changes through pregnancy, nursing or weight shifts — and never uploads a thing.
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