How to measure your bra size correctly

Short answer: You need two measurements. The circumference just under the bust gives the band size, and the circumference over the fullest point gives the cup. The difference between the two is the cup size, and band and cup are linked.

Before you measure

Use a soft tape measure and measure without a bra or in a thin, unpadded one. Stand in front of a mirror so you can see that the tape lies level all the way round, including at the back. Measure twice and use the average. A tape that sits crooked is the most common cause of a wrong result.

The band measurement under the bust

Measure snugly and level just under the bust while breathing out. That number becomes your band size. The tape should sit close to the skin without digging in. If you are between two sizes, choose the smaller one, as the band relaxes over time. Read more in the size guide for full bust.

The bust measurement at the fullest point

Measure loosely and level over the fullest point without pressing. The tape should rest on the skin, not pull. Standing straight with your arms by your sides gives the most accurate measurement. Some prefer to lean forward slightly, so the whole breast is included in the measurement.

The difference gives the cup

Subtract the band measurement from the bust measurement, and the difference gives the cup size. Each cup size usually corresponds to about two and a half centimetres. The bigger the difference, the bigger the cup. Charts vary a little between brands, so always use the size chart for the model you are looking at.

Band and cup are linked

If you go one size down in the band, you need to go one up in the cup to keep the same volume. That is why two different sizes can fit equally well. Knowing this makes it easier to adjust if the first size does not sit quite right. See bamboo bras without underwire.

Test at the end

The band should sit level and lift about two centimetres from your back. If you can lift it further, it is too loose. The centre between the cups should lie flat on the breastbone, and the cup should hold the whole breast without spilling over. Move around and raise your arms to check everything stays put.

Typical signs of the wrong size

If the band rides up at the back, it is too big. If your shoulders ache, the straps are carrying too much, and again the band is too loose. If the breast spills over the edge, the cup is too small. If there is a gap between cup and breast, it is too big. Most mistakes are fixed with one size up or down.

Measure again from time to time

Bodies change over time, and so does your size. Measure again if your bra suddenly fits differently, or if it has been a long time since you last measured. It takes a few minutes and saves you from wearing a size that no longer fits. See the full range under bamboo underwear for women.

In short

Measure snugly under the bust for the band and loosely over the fullest point for the cup. The difference gives the cup size. Band and cup are linked, so if you go down in one, go up in the other. Finally, check that the band sits level and lifts only about two centimetres.

Frequently asked questions

How do I measure my bra size?

Measure snugly under the bust for the band and loosely over the fullest point for the cup. The difference gives the cup size, and the band measurement gives the band size.