When your bra size no longer fits

Short answer: Size changes with weight, age and cycle. Measure again once a year instead of buying the same as last time, so you do not wear the wrong size for a long while without knowing it.

The band is what changes first

A band that has gone loose means all the support disappears, and this shows up fastest as straps slipping down through the day. When in doubt, the band is almost always what you should remeasure first. See bamboo bra without underwire.

Measure in two places for a reliable result

Measure under the bust and over the fullest point, where the difference gives the cup and the measurement underneath gives the band. Write the numbers down so you can compare them with the chart at bamboo tops for women and the bra pages.

Soft styles cover a wider range

A soft bra without underwire fits over a larger range than one with fixed cups, because the fabric gives way to small changes in the body. That makes them a good choice if your size fluctuates a little through the cycle. See bamboo underwear for women.

Weight changes affect cup and band differently

A small change in weight usually shows up first in the cup, while a larger change often also shifts the band measurement. That is why checking the cup alone is not enough if you are unsure whether the size still fits.

Age changes the elasticity of the tissue itself

Over time skin and the surrounding tissue lose a little of their own tension, and that can make a previously perfect size feel different even without a change in weight. It is a completely natural process, not a sign that anything is wrong.

The cycle can cause temporary fluctuations

Many notice the bust is a little fuller at certain points in the cycle, which can make a fixed bra feel tight for short periods. A soft style with good elasticity handles fluctuations like this better than one with fixed cups.

Signs it is time to remeasure

Straps that constantly slip, a band that curls up at the back, or a cup that no longer fully covers are all signs the size has changed. Do not wait too long to remeasure once you recognise these signs.

Always try before settling on a fixed size

The same stated size can fit differently from style to style, even within the same brand. So try several styles, and put more weight on how the band and cup actually feel than on the number on the label.

Washing also affects how long the size lasts

The elasticity in both band and straps wears slowly through normal use and washing, and that can mimic a change in body size even when the body has not changed. A cool wash extends the life of both parts.