AI Bra Size Guesser

The AI looks at garment-level fit signals rather than at your body: where the band of your current bra appears to sit, whether it rides up at the back, how a fitted top drapes across the bust, visible spillage or gaping at the cup edge, strap tension, and the apparent proportion between your ribcage and the fullest part of the bust. From those cues it suggests a likely band-and-cup range, names the sister sizes worth trying alongside it, and points out which cue would tell you to size the band down or the cup up.

A clear, front-facing photo of yourself from the shoulders to the waist, fully clothed in an ordinary well-fitted top (not baggy, not a bra, swimwear, or underwear), standing upright with arms relaxed at your sides and the camera at chest height.

Treat every result here as a guess, not a measurement. Estimating a bra size from a single photo is inherently imprecise: clothing thickness, posture, camera angle, distance, and lens all change the apparent proportions substantially, and the visible fit cues the AI relies on can be masked entirely by a loose or structured top. On top of that, bra sizing is not standardized. The same body routinely needs different labelled sizes across brands, styles, and cuts — a 34C in one brand can be a 32D or a 36B in another, which is why sister sizes matter. This tool is a starting point for what to try on. For an actual size, measure your underbust and your bust at the fullest point with a soft tape, or get fitted in person — and see a doctor rather than a sizing tool for any pain, skin irritation, or change you are concerned about.

The claim that most women wear the wrong bra size has been repeated by lingerie retailers and fitting specialists for over two decades, and while the exact figure varies with whoever is doing the counting, the underlying problem is real and structural: band and cup are not independent measurements. Go down a band size and the cup volume shrinks with it, so the same physical volume carries a different letter on a different band. That relationship is what "sister sizing" describes — sizes that hold roughly the same cup volume on a different band.

How to measure your bra size with a tape

1. Band: Wrap a soft tape around your ribcage directly under your bust, level all the way round and pulled snug. Breathe out, then round to the nearest whole inch — that is your band size.
2. Bust: Measure around the fullest part of your bust with the tape level and resting against you, not pulled tight enough to compress anything.
3. Cup: Subtract the band number from the bust number. Each inch of difference is roughly one cup size: 1 inch is an A, 2 a B, 3 a C, 4 a D, 5 a DD, 6 a DDD.

Measure in an unpadded bra or none at all, and check in a mirror that the tape is level across your back — a tape that rides up behind you is the single most common reason a home measurement comes out a band size too small. You may also see older guides telling you to add four or five inches to the band measurement; most fitters have dropped that step, which is one more reason the same body ends up with different labels in different places.

The practical version: if the band rides up your back, the band is too big — go down a band and up a cup. If the cups gape, go down a cup. If the underwire sits on breast tissue rather than the ribcage behind it, go up a cup. Those three rules solve more fit problems than any photo-based guess will, which is worth knowing before you weigh what this tool tells you.

Cup letters also do not mean the same thing internationally — UK, US, and EU systems diverge above a D, so a size that fits in one system may be labelled differently in another.