Measure once. Know your size.

The free bra-size and shapewear fit finder that shows its work — no email, no login, and your measurements never leave your browser.

Find my size
Size calculatorHow to measureSister sizesShapewear finderFAQ
BRA-SIZE CALCULATOR

Enter two measurements. Get your size in seconds.

Your underbust (just below the bust) and your bust (the fullest point). The tool shows the exact math, then hands you your sister sizes.

🔒 Runs entirely in your browser. We store nothing and ask for no email.

HOW TO MEASURE

Two numbers, one tape measure

Underbust: snug and level, no bra or a thin non-padded one. Bust: over a lightly lined bra so the number reflects your natural shape. Keep the tape parallel to the floor — that's the whole method.

See the full measuring guide →
THE PART MOST TOOLS SKIP

Sister sizes, explained

When the cup fits but the band doesn't, you don't need a different cup volume — you need the same volume on a different band. Go up one band, down one cup (and the reverse). That's why a 34C, 36B, and 32D all hold about the same.

Your sizeBand too tight? TryBand too loose? Try
34C36B32D
36D38C34DD
32B34A30C

The calculator generates this row for whatever size you enter — so a sold-out size still leaves you three or four real alternatives.

Find shapewear that fits your shape

Pick a goal — the finder maps it to a garment category, then shows you how to size it from your body measurements (not your bra label).

Smooth a tummy

High-waist shorts/goal
  • ✓Sizes from natural waist + hip
  • ✓Targets the lower-tummy line
  • ✓Look for a wide, no-roll waistband
  • ✓Honest note: smoothing is temporary
Use the finder →
推荐

Shape the full torso

Bodyshaper / bodysuit/goal
  • ✓Sizes from waist + hip vs. chart
  • ✓Smooths bust-to-hip in one piece
  • ✓Pick the right leg + gusset style
  • ✓Body returns to its shape after wear
Use the finder →

Waist focus

Shaping waist piece/goal
  • ✓Sizes from natural waist
  • ✓Honest waist-training caveat included
  • ✓No fat loss, temporary slimming only
  • ✓Limit wear; consult a professional
Use the finder →
"There's no 'correct' body — only a correct measurement. A calculator gives you a confident starting size, then the loosest-hook test and the mirror finish the job."
— Dana Reyes, Certified bra-fit specialist · Shape Finder

Why people keep the tab open

"Finally a calculator that shows the arithmetic instead of just spitting out a letter. Checked my own math in ten seconds and the sister sizes saved me when my size was sold out."

P
Priya M.
Used the sister-size finder

"No email wall, no 'sign up to see results,' nothing stored. I trust a sizing tool way more when it isn't trying to capture my inbox."

J
Jordan T.
First-time visitor

"The honest waist-trainer section is what sold me. It told me what the garment won't do, with real sources. That's rare."

L
Lena K.
Read the shapewear guide
It's free, and it stays in your browser
No login, no email, no measurements saved or sent anywhere. Run it as many times as you like.
Calculate my size

Bra sizing, answered

Do I measure with a bra on or off?+
Measure your underbust (band) with no bra or a thin non-padded one, snug and level. Measure your bust over a lightly lined, non-push-up bra so the number reflects your natural shape. Keep the tape parallel to the floor.
My difference lands between two cups — which do I pick?+
Round to the nearer half-inch and try both the calculated size and its sister size. Cup fit is where personal preference and brand cut matter most, so the calculator narrows it to two candidates rather than one.
Does my bra size tell me my shapewear size?+
No. Smoothing garments are sized from your natural waist and hip measurements against the maker's chart — not from your bra label. Measure those separately; a bodyshaper that's too small digs in rather than shaping better.
Do you store my measurements or need my email?+
Neither. The entire calculation runs client-side in your browser. Nothing is uploaded, saved, or tied to an email — close the tab and it's gone.
Is a measured size guaranteed to fit?+
No. Sizing isn't standardized across brands, so the calculator gives a confident starting size to try on — ideally in a couple of sister sizes. When in doubt, trust the mirror and the loosest-hook test over the tag.
HOW WE BUILT THIS

The method is public

Shape Finder is a first-party tool: we wrote the formula, document it on our Methodology page with the studies we rely on and a 'last verified' date, and publish a changelog. Health claims about shapewear and waist training are sourced to Cleveland Clinic and named medical authorities, never asserted as our own. We sell nothing.

Methodology & formulasAbout & how we make moneyPrivacy (in-browser math)

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New sizing guides, occasionally

Optional and email-only — the calculator never needs it. We send a note when we publish a new fit guide. No spam, unsubscribe anytime.