How to find your size
Sister sizes for 90C: 85D, 95B. If 90C holds well around the band but the cup digs in or gapes, reach for a sister size instead of changing only the letter — cup volume stays similar while the band changes.
At this cup size, padded and push-up models work well because they add volume, as do smooth cups under fitted clothes.
Remember that size grids differ between brands — we publish the manufacturer's chart with every product. We have explained how to measure on our How to find your size page. Parcel locker delivery is PLN 12.99, free from PLN 199, and you have 14 days to return.
A band of 90 corresponds to an underbust measurement in the 88-92 cm range, and a C cup means a difference between measurements of around 16-18 cm. It is an in-between size: the band is already wide, so it provides plenty of support on its own, while the cup is moderate enough that the choice of styles stays broad.
At a wider band, a common problem is the lower edge rolling. A wide elastic and a straight-cut back panel, without a deep scoop, counteract this. If the band rolls despite a good size, the cause can also be an over-tightened strap pulling the back upwards.
Before buying, take your measurements and set them against our size guide. If you want the same cup shape in other bands, see cup C, and you will find style tips in our guide.
If you are buying with day-to-day changes in mind, remember that your ribcage measurement can shift by a centimetre or two across the monthly cycle and after a large meal. So measure at a consistent time, and where the result falls between two sizes, choose the narrower one, since the fastening gives you room to adjust.
What to look out for
The sister equivalents are 85D and 95B. Switching changes the band length while the cup volume stays similar.
Which style to choose
For everyday wear, full-cup and semi-padded models are comfortable, with a cup that supports without imposing a shape. Under fitted blouses a smooth moulded cup is better, and under jumpers and looser cuts, lace, which is lighter and warms up less.
