Do I Need a Bigger Cup or a Smaller Band?

Put the bra on, fastened on the loosest hook, and scoop and swoop before you start. The tests mean little otherwise.

Test 1: the band

• Look side-on. Is the band higher at the back than at the front?
• Pull it away from your spine. Does it stretch more than about two inches?
• Slip the straps off. Does the bra drop?

Any yes: the band is too big.

Test 2: the cups

• Is there a ridge or bulge at the top or sides of the cup?
• Is the centre panel lifting off your breastbone?
• Press the wire at the side. Is it resting on soft tissue?

Any yes: the cups are too small.

Read your result

Why "both" is so common

The two problems tend to arrive together. Size guides that add inches to the underbust give a band that is too big, and the cup letter is then worked out against that inflated band, so it comes out too small. See why the +4 method is wrong.

They also hide each other. A loose band lets small cups shift out of the way, so the overflow is less obvious. And small cups hold the bra off the body, which makes a loose band feel snug. Fix one and the other becomes visible.

Why the cup letter goes up when the band goes down

This is the part that confuses people. Cup letters are relative to the band. A 34C cup is smaller than a 36C cup. If you go down a band and want the same cup volume, you must go up a letter: 36C and 34D hold the same amount.

So in the third row of the table, one letter of the two is simply compensating for the smaller band. Only the second letter is a real increase in cup size. A move from 36C to 34DD sounds dramatic and is one true cup size bigger.

Two traps

Going up a band to fix tight cups

From 34C to 36C you get more cup, which helps, and a looser band, which does not. The right move is 34D.

Going down a band and keeping the letter

From 36C to 34C the band improves and the cup shrinks. If the cups were right before, you will now spill out.

When the test says the band is too tight

If the band is painful on the loosest hook, do the back-to-front check before changing it: fasten the bra around your ribs with the cups behind you. If it is comfortable like that, the band is fine and the cups are too small. If it is still tight, go up a band and down a cup letter. More in is my bra band too tight?

Try it, then test again

Each change can reveal the next, so run both tests on the new size. Two or three rounds usually finishes the job. The step-by-step version of this approach is in how to find your bra size without measuring, and the quickest shortcut is to measure.

Frequently asked questions

Should I go up a cup size or down a band size?

Test them separately. If the band rides up or pulls away easily, go down a band and up a cup letter to keep the same volume. If tissue bulges over the cups or the centre panel floats, go up a cup on the same band. Many people need both.

If I go down a band size, do I need to change the cup?

Yes, if the cups fitted before. Cups are smaller on a smaller band, so go up one letter to keep the same volume: 36C becomes 34D.

My bra feels tight. Does that mean I need a bigger band?

Not necessarily. Cups that are too small push the bra away from your body and make the band feel tight. Fasten the bra back to front around your ribs. If the band is comfortable that way, you need a bigger cup, not a bigger band.