If you want to know your bra size without guesswork, appointments, or sign-ups, this site exists for exactly that. Find Your Bra Size is a small, free website with one job: helping you find a bra that fits, starting from two tape measurements.
What you can do here
Everything on the site is free and runs entirely in your browser:
- Bra size calculator: enter your snug underbust and standing bust to calculate bra size in inches or centimeters, with US and EU equivalents included.
- Fit guide: how to measure with a tape, step by step, and what a good fit feels like across band, cups, gore, and straps.
- Bra basics: how to calculate cup size from the bust-minus-underbust difference, what the number and letter mean, and how sister sizes work.
- Sister size finder, size converter, and fit checker for adjusting bands, comparing UK, US, and EU labels, and verifying a bra you already own.
How the method works
To calculate bra size here, you only need those two numbers. Your band comes from your underbust rounded to the nearest even number; to calculate cup size, take the difference between bust and underbust at roughly one letter per inch. That result is a starting size, not a verdict. Shape, fabric, and brand all matter, so every tool points you back to the physical fit checks.
Private by design
There are no accounts and no sign-ups. The numbers you enter are processed by JavaScript running on the page and are never sent to a server or saved anywhere. You can verify this yourself by viewing the page source: the calculation code is plain and readable.
An honest limitation
Everything here is educational guidance, not professional fitting or medical advice. Sizes and fit vary by brand, fabric, and body shape, so always try a bra on and trust how it feels through the day.