Bra Sized Tankinis

Bra Sized Tankinis

How Swim Bra Sizing Works

A bra size is two measurements pretending to be one label. The number is the band, measured around the ribcage under the bust. The letter is the cup, which is the difference between that measurement and the fullest part. Neither means anything on its own, which is why a 34D and a 38D are not the same size in any useful sense.

The consequence people find counter-intuitive is sister sizing. Cup volume moves with the band: a 36C holds roughly what a 34D holds, because the letter is relative. Going up a band size and down a cup letter gets you the same volume on a looser frame, and it is the standard adjustment when a band feels tight but the cups fit.

Swim adds a complication. Wet fabric stretches and recovers differently from the fabric in a bra, and a swim top is expected to be firmer when dry than a bra would be, because it has to still be holding after an hour in water. A top that feels slightly firm in the changing room is usually correct.

Reading a Top Without a Cup Letter

Most swim tops are sold in S, M and L rather than in bra sizes, and that includes a great deal of what turns up under this search. It is still perfectly possible to judge support — the construction tells you what the label does not.

Look for four things. A band at least an inch and a half wide, which spreads load instead of concentrating it. Cups made from more than one piece of fabric, because a seam is what creates shape rather than just a curved surface. A wire that is fully encased. And straps that adjust at the back, where you can reach them, rather than being sewn down.

A top with all four will support a fuller bust properly whatever letters are or are not printed on it. A top with none of them will not, even in a size that measures correctly. Underwire tankinis are the most reliable place to start looking, because the wire tends to arrive with the rest of the structure.

Two Numbers, Two Halves

This is where a two piece earns its place for anyone shopping by bra size. A bust measurement and a hip measurement rarely land on the same garment size, and a single garment forces you to pick which one to disappoint.

Buy the halves apart and each takes its own number. Take the top from the bust and the ribcage, take the bottom from the hip, and stop trying to average the two. It is the same principle that makes cup sized tops worth seeking out in the first place, applied to the half of the outfit that has nothing to do with cup size.

Measure over nothing rather than over a bra, and measure the ribcage snugly and the bust loosely. Those two habits fix more sizing complaints than any amount of size-chart study.

When the Band Is the Problem

Almost every complaint that gets described as a cup problem is a band problem wearing a disguise. Straps digging into the shoulders, cups gaping at the top, the whole top riding up at the back — all three are what happens when the band is not holding and the straps have taken over.

The check takes a moment. The band should sit level all the way round, not higher at the back than at the front, and you should be able to get one finger under it and no more. If it rides up when you raise your arms, it is too loose whatever the label says.

Going down a band size and up a cup letter keeps the same volume and fixes it. That single adjustment resolves more than any other, and it is the reason wired tops with a genuinely wide underband outperform identical-looking ones with a narrow strip of elastic. On a plus size top the difference is larger still, because there is more weight for the band to fail under.