How to measure your bra size
Two measurements, band and bust, give you a bra size. Take them with a soft tape, then let the calculator do the maths and the conversion.
Two measurements give you a bra size: the band and the bust. Take them with a soft tape measure, ideally while wearing an unpadded bra or none at all, and stand relaxed with the tape level.
Getting the band snug is the most important step, because the band does most of the support and it anchors the cup calculation.
- Measure the band. Wrap the tape around your ribcage directly under the bust. Keep it snug and level. Round to the nearest even number in inches to get the band size.
- Measure the bust. Wrap the tape loosely around the fullest part of the bust, keeping it level across the back. Do not pull tight.
- Find the difference. Subtract the band measurement from the bust measurement. Each inch of difference is roughly one cup size, so a one inch difference is an A cup and a four inch difference is a D.
- Combine into a size. Put the band number and the cup letter together, for example 34C, then use the chart to convert to UK, EU or other systems.
Calculate your size
Enter the two measurements you just took to get your size in every system.
Measuring questions
How do I measure bra size at home?
Measure your ribcage under the bust for the band and the fullest part of the bust for the cup, both with a level tape measure. The band is the first measurement rounded to an even number, and the cup is one letter per inch of difference between the two.
Should I add inches to my band measurement?
Modern fitting rounds the underbust measurement to the nearest even number without adding inches. Older guides told you to add four or five inches, which now tends to give a band that is too loose.
Last reviewed and updated on July 2, 2026. Conversion tables are checked against published international sizing standards.