Bra Size Calculator
Calculate Your Bra Size
For better results or to learn how to measure your breasts, please see our measuring guide below.
Your Calculated Bra Size
Enter your measurements above to see results
How to Measure Your Breasts
You'll need a soft measuring tape, bare breasts, and a few minutes without interruption.
No bra, no top. Just you and the tape.
There are six measurements in total.
That's more than most calculators ask for — and that's the point.
Each one captures your body in a different position, because your breasts don't behave the same way when you're standing as when you're leaning forward or lying down. Together, they give the calculator a complete picture.
Take your time. Precision here matters.
1. Loose Underbust
Wrap the tape around your ribcage, just under your breasts. Let it sit lightly against your skin — no pulling, no tension.
2. Snug Underbust
Same spot, but this time pull the tape snug. It should feel like a comfortable bra band — secure, but not tight. This is your most important measurement.
3. Tight Underbust
Exhale fully and pull the tape as firm as you comfortably can. There shouldn't be any pain — just a real, definite tension.
4. Standing Bust
Stand naturally and measure around the fullest part of your breasts, keeping the tape level and loose enough that it isn't compressing anything.
5. Leaning Bust
Bend forward until your torso is roughly parallel to the floor and let your breasts fall freely. Measure around the fullest part from there.
6. Lying Bust
Lie flat on your back and relax completely. Measure around the fullest part one more time.
Why Six Measurements Instead of Two?
Any other bra size calculator will ask for two numbers and call it done.
The problem is that two measurements taken in one position can't account for tissue behaviour, projection, or how your breasts actually move through the day.
Your breasts don't sit still, so your measurements can't either.
Standing shows your natural position.
Leaning captures total volume.
Lying reveals how your tissue distributes.
The three underbust measurements together tell us how your band should behave. None of these alone gives the full picture. But all six together get much closer.
Bra Sizing Inaccuracies
This calculator just gives you a starting point — a well-informed one, but a starting point none the less.
Breast tissue varies from one person to another.
Some tissue is denser, some is softer. Some shapes are more projected, some are shallower. Most people have one side slightly larger than the other. Human bodies don't fit neatly into any formula, including ours.
If your result doesn't feel quite right in a bra, that's not a failure — that's just how bra fitting works.
Use the number as your starting point, try it on, and adjust from there.
Our guides on fit and breast shape can help you understand what to look for and how to move from a starting size to a size that actually works.
Your size will also change throughout your life — sometimes gradually, sometimes quickly. Remeasuring every so often is worth doing, not just once.