What does band size mean?

I keep hearing people call a band that stretches to 29″ or 30″ a “true 30”. That makes zero sense to me, since I measure band size with an exhaled measurement and would consider someone with an exhaled measurement of 30″ to be a 30 band, so the band would need to stretch to 32-33″ for them to be able to breathe. However, if you measure for bands with a fully-inhaled measurement, a 30 band would only need to stretch to 30″ (29″, though, would still be a bit too small to call a “true” 30).

Some other factors (bodies): Ribcages expand different amounts. My snug exhaled measurement is 29″… my tight fully-inhaled measurement is 32″ (3″ difference). My friend’s ribcage expands from 28″ to 33″ (5″ difference). From our exhaled measurements, my friend would end up in a smaller band… but being able to breathe is important! So she’s more comfortable in a 32 band, whereas 30s are usually fine for me.

What does size on the label mean?

Some brands call a band that stretches to 30″ a 30… and some call a band that stretches to 33″ (and would fit someone with an exhaled ribcage measurement of 30″) a 30. Basically, it varies by brands. Here’s a fairly random list of stretched band lengths of various 30-band bras (measured with full but not-breaking-elastic stretch). Check out the range:

Tutti Rouge Betty (creme) 30GG: 28.5″

Ewa Michalak SM Burek 65H/30H: 29″

Ewa Michalak PL Black 65HH/30HH: 29″

Curvy Kate Entice (black) 30HH: 29″

Comexim Iris: 29″

Parfait Charlotte (dusky rose) 30HH: 29.5″

Cleo Meg: 29.5″

Parfait Casey (light blue) 30G: 30″

Freya Deco (black) 30GG: 31″

Cleo Sasha 30GG: 31″

Freya Deco (beige) 30G: 32.5″

I have 32 and 34 band bras that fit much tighter than the beige 30G Deco, and 28 band bras that fit significantly looser than the 30GG Tutti Rouge Betty!

Now I haven’t by any means done a comprehensive analysis, but my guess is as follows: Comexim, Ewa Michalak, and Parfait seem to label their bands with a fully-stretched measurement, whereas Freya band sizes appear to match up with a slightly-stretched measurement. Thus, using a snug inhaled measurement as band-size will be more likely to get you a well-fitting bra with Comexim, Ewa Michalak, and Parfait and using a snug exhaled measurement as band-size will probably get you a good fit in brands that size like Freya.

Some other factors (bras): Even within the same style bra, different colors and even cup sizes can affect band stretch! Dark dyes can make a band fit a full size smaller than its light colored counterparts… my 30GG black Deco is a lot tighter than its beige counterpart.

And cup size is also interesting– a 30HH bra will have more non-stretch cup material taking up the band space than a 30D will have. I don’t have a huge size range of bras in the same style, but I do happen to have a 28H (blue) and a 28HH (black) Curvy Kate Tease Me:

The bras are both 28 bands, but the 28H has more material beyond the underwires than the 28HH. This is because the underwires on the 28HH are wider than the underwires on the 28H. While the width of the underwires does make the overall unstretched lengths of the bras roughly equal, this photo shows that the 28H has the capacity for a good deal more stretch than the 28HH. It doesn’t quite feel like a full bandsize difference, but that’s because we’re comparing bras that are only one cup size apart. I’d love to see this compared in a wide range (e.g. 30D-30J) to show just how much cup size (really, underwire width) affects stretched band length. Some brands may make up for this by adding length to the band in larger cup sizes, but there are at least slight difference within a range of a few cup sizes.

Which one is right?

Niether. How we chose to measure and label is arbitrary. But having different systems in play can make an already confusing task even more confusing. I’d love to see this standardized, but I don’t think it will happen any time soon.

But remember that different brands size their bands differently! If you use your exhaled measurement as a band size to order from a company that labels their bands with their fully-stretched measurement, you’re going to have some trouble breathing. Likewise, if you use an inhaled measurement as a band size to order from a company that labels their bands with their slightly stretched measurements, you’ll end up with a band 1-2 sizes too big for you.