How to Find Your Bra Size at Home

Short answer: You can find your bra size at home with an ordinary tape measure. Measure under the bust and over the fullest part of the bust, and you have the two numbers a size guide uses to work out both band size and cup size.

How to measure

Measure snugly but comfortably directly under the bust. That number gives your band size, for instance 75 or 80. Then measure loosely over the fullest part of the bust. Always measure without a thick bra or jumper, and stand relaxed with your arms down by your sides.

The difference gives the cup

The difference between the two measurements decides the cup size: around 13 cm corresponds to an A cup, 15 cm to a B cup and so on upwards. It is a rule of thumb rather than an exact formula, but it gets you close enough to choose a starting size.

The tape has to be level

If the tape sits at an angle at the back, the number comes out too large, and then you end up with a band that is too loose. Ask someone to help, or measure in front of a mirror so you can see your back. That is the most common source of a wrong measurement.

Measure at a neutral time

The body changes over the day and over the month. Measure in the middle of the day rather than straight after training or a large meal, and avoid the days when you already feel swollen. That gives you a number that suits most days.

Wireless models are more forgiving

A bamboo bra without underwire is elastic and shapes itself to the body, so it forgives small variations in the measurements. If you are between two sizes, you can often choose the one that feels better. See bamboo bras without underwire and try the smaller first.

Check the brand's own guide

Sizes vary from brand to brand, and a number at one brand is not the same at another. If you are buying from JBS of Denmark, use the size guide for JBS of Denmark women rather than going by the size you usually take.

How to check that it fits

Raise your arms and lower them again. If the band rides up at the back, the band size is too large. You should be able to fit two fingers under the band all the way round, but no more than that. If the straps cut in, the band is not carrying enough.

Measure again after a couple of years

Many people buy the size they have always bought and wonder why things suddenly pinch or slide. The body changes, and the chart does not. Two minutes with a tape measure solves it more often than changing brand does. See bamboo underwear for women. See also finding the right size in bamboo clothing.