Choosing the right bra size without underwire as a reference

Sizing a wireless bra is genuinely different from sizing an underwired one. The cup is moulded rather than structured, and the band works differently without a rigid wire to anchor it. If you have only ever worn underwired bras, the first bra can feel unfamiliar even in the right size.

Why your underwired bra size is a starting point, not a guarantee ¶

Underwired bras are sized using a band measurement and a cup volume, and the wire provides a fixed structure that holds the cup in place. A bra has no wire, so the cup shape is maintained by the knit itself and by the band tension. This means the fit depends more on the overall stretch of the fabric than on a precise cup-to-band ratio.

In practice, women who wear a 75B in an underwired bra often find that a small or medium bra fits them well, but the correspondence is not exact. The best approach is to measure your underbust and your fullest bust point in centimetres and compare those measurements to the size guide, rather than converting from your underwired size.

What a correct fit feels like in a bra ¶

The band should sit level all the way around and feel snug without digging. If it rides up at the back, the band is too large. The cups should contain the breast without any fabric gaping at the top or sides. Because there is no underwire, there will not be the defined separation you get from a structured bra, but there should be no spillage.

Straps should lie flat on the shoulder without slipping. In a bra, the strap is usually part of the knitted body rather than a separate piece, so it does not adjust as precisely as a traditional strap. Check the adjustment range in the product description before ordering.

When to size up and when to size down ¶

If you are between measurements, size up for the band and down for the cup volume. A slightly larger band is more comfortable than a tight one in a wireless style, because there is no wire to compensate. A slightly smaller cup is better than a larger one, because excess fabric in the cup will fold rather than sit flat.

The measurement guide on each product page gives the specific centimetre ranges for each size. It takes two minutes to measure and it is more reliable than guessing from a clothing size.