Bra Size Calculator
Find your US bra size from two tape measurements. The band is your underbust rounded to the nearest even number, and the cup letter comes from the difference between bust and band.
Inputs explained
- Underbust (band) measurement — Measure snugly around your ribcage, directly under the bust, in inches.
- Bust measurement — Measure around the fullest part of the bust, in inches, without compressing.
How to use it
- Fill in the fields above — each input has a hint describing exactly what to enter
- Press Calculate to get your result instantly, right on this page
- Copy the result, save the tool to favorites, or share and embed it anywhere
Understanding the result
Example: An underbust of 31" rounds to a 32 band; a 36" bust is 4" larger, which is a D cup — size 32D.
Frequently asked questions
Why does my band size come out different from the number on my current bra? The calculator rounds your underbust measurement to the nearest even number, which is the standard US sizing convention — so an underbust of 31" becomes a 32 band even though the raw number is odd.
What if the bust-to-band difference falls between two cup letters? The cup is determined by the whole-inch difference between bust and band measurement (for example a 4" difference maps to a D cup), so re-measuring carefully matters more than the calculator — a half-inch error can shift you a full cup size.
Is the Bra Size Calculator free to use? Yes — it is completely free, with no sign-up, no download and no usage limits. You can use it as often as you need.
Is my data private? Yes. The calculation runs entirely in your browser — the values you enter are never sent to our servers, stored or shared with anyone.
What information do I need? Just the following: Underbust (band) measurement, Bust measurement. Each field includes a hint explaining exactly what to enter.
Can I use it on my phone? Yes — the tool is fully responsive and works on any device, and the same calculator is available in the EasyWorkCalcs mobile app.
Privacy
Everything you enter into the Bra Size Calculator is processed entirely in your browser. Nothing is uploaded, stored or shared — your data stays on your device.