Underbust measurement and cup size in a soft bra

Short answer: The fit of a bra depends on two things: the underbust measurement, which decides the band size, and the cup, which decides how much room there is for the bust. Here is a simple way to measure and tips for judging whether a bra fits properly.

What underbust measurement and cup mean

A bra size consists of a number and a letter. The number shows the underbust measurement, which is the circumference just under the bust, and the letter shows the cup size, which depends on the difference between bust and underbust. Both must fit before a bra sits well, and changing one affects the other.

How to measure the underbust

Measure the circumference just under the bust with a tape that lies flat and level. Breathe out and measure without pulling tight. Compare the number with the size guide. If you want to see a bra where trying it on may be easy, look at the bamboo bra and read how the sizes are built up.

How to find the cup size

Measure the circumference around the fullest part of the bust and subtract the underbust measurement. The difference indicates the cup size. The bigger the difference, the bigger the cup. This is only a guide, so always try the bra on and judge the fit. Measurements and sizes can vary between brands and models.

The band carries, not the cup

The band carries most of the weight, so it should sit firmly without pulling. It should lie level around the body and not ride up at the back. If you can slip two fingers under the band but no more, it sits roughly right. If it is too loose, the bra loses its support.

The cups should hold without cutting in

The cups should enclose the bust without cutting in or leaving gaps. If the bust spills over the edge, the cup is too small, and if the fabric wrinkles, it is too big. Look at it in the mirror with a T-shirt over it, so you can see whether anything shows under the clothes.

The straps and the centre front

The straps should sit on the shoulder without cutting in or sliding off. They adjust the final finish but do not carry the weight. The centre front should lie flat against the breastbone. If it lifts away, the cup may be too small. Try different strap settings and notice what feels calm.

Combine with a top and underwear

Under a bra you can wear smooth bamboo underwear for women that lies flat. Over it you can wear a soft top from the bamboo tops for women. That makes the whole comfortable, and you avoid lines or rubbing under your clothes during the day.

Washing, care and when to replace it

Wash the bra according to the label on a gentle programme, preferably in a wash bag, and let it air dry. High heat can wear the elastic. Replace the bra when the band has become loose or when the cups no longer hold their shape. If you have pain or discomfort, talk to your doctor or a professional.

Frequently asked questions

How do I know my bra fits properly?

The band lies level and firm without pulling, the cups enclose without cutting in, and the straps do not slide. If in doubt, try another size or look at a measuring guide.

Should I measure myself before buying?

It is a good idea to measure, but try the bra on too. Sizes can vary between brands, so the measurement is a guide and not a certainty.

How often should a bra be replaced?

Replace it when the band has become loose or the cups no longer hold their shape. It depends on how often you wear and wash it.