THE BAND & STRAPS:

Always start with the band on the loosest hook: it should be snug and straight against your back. You should be able to slip fingers beneath the band without trouble, but not enough to pull it away from your back. If the band lifts in the back, the band size is too big.

Try lifting your arms above your head. Does the bra shift dramatically up? Do your breasts slip out of the bottom? Then the band is too big.

Straps should be snug, but not too tight – the support of a bra should come from the band, not the straps.

THE WIRES:

The underwires at the front of the bra should sit flat on your sternum. If the wires are standing away from your chest, the cup size you are wearing is too small.

The underwires at the side of the cup should extend to the edge of your breast tissue, without digging in. If you appear to be spilling out the sides of the cup or can see a “dimple” from your underwire, your cup size is too small.

THE CUPS:

Make sure all your breast tissue is pulled into the cup (an easy way to do this is to learn forward as you put the bra on, or pull the tissue into the cup).

Turn to the side and look at the edge where the bra meets your breast tissue. Is it digging in? Are you spilling out? The cup size is too small.

Is there puckering or excess fabric in the cup, especially at the top or at the seams? The cup size is too big or too deep.

You will find that there is a lot of variation in fit between demi bras and fuller cups, and your sizing may need to be different depending on which kind you are buying. There are also differences with every piece in how far apart the cups are spaced, and how wide the “u” of the underwire is – these can also affect the sizing and fit of the bra.