Bra size calculator
Wear a lightly lined or unlined bra, or measure bare. Keep the tape level and snug, never tight.
Your measurements
Two numbers, under two minutes.
Enter your measurements to see your size and sister sizes.
How to measure
Do it in front of a mirror and measure twice.
1
Under bust
Wrap the tape around your ribs, right under your breasts. Keep it level and snug. Breathe out, then read the number.
2
Bust
Wrap the tape around the fullest part of your chest. Keep it level and loose enough to lie flat without pressing.
3
Compare
The difference between the two numbers decides your cup. A larger difference means a larger cup.
4
Round and note
Write both numbers down. The calculator rounds sensibly and shows close alternatives.
Reading your result
Your result is a starting point, not a verdict. Letters mean different things from brand to brand, and a size can change with style, fabric and stretch.
Try your result and its sister sizes. Choose the one where the band is snug and level, the cups are smooth and the straps stay put.
Common measuring mistakes
Pulling too tight
A tight tape gives a band number that is too small. Snug, not squeezing.
Tape tilting
If the back sits higher than the front, the numbers will be off. Check the mirror.
Measuring once
Repeat each measurement. Use the number you get most often.
Calculator FAQ
Do I measure over a bra?
Bare or over a thin, unpadded bra both work. Avoid padded or push-up bras.
What if I’m between sizes?
Try both sizes and sister sizes, and pick the one that passes the fit checklist.
Do you save my numbers?
No. The calculator runs entirely in your browser — your measurements are never sent to us or stored anywhere.
Got your size?
Run through the five-point fit check to confirm it works on you.