Sister Sizing

Let’s get the hard part over first-sister sizing. It seems easy at first. Just look at the diagonal boxes on the chart. You go up a band, and down a cup or vice versa. When you think harder about it, it starts to make less sense. Why does the band go down 2 inches but the cup only changes one size? This is because the cup size isn’t a measure of the volume of your breast tissue, but a measurement of the difference between your band size and the fullest part of your chest. Thus the band size changing on two people with the same tissue volume in the cup would yeild two different cup sizes.

The diagonal boxes on the chart show which band/cup combinations have the same breast tissue volume. So a 30F and a 32E both have have the same volume. The picture below is a crude representation of how the same cup volume looks on different band sizes.

The picture below represents how in the same band size, the cup volume grows.

The next image shows how the same cup size is actually different tissue volume in each band size.

Thus, someone with a 36″ band and a 6 inch difference between their underbust and bust measurements would be a 36F. If they only have a pattern that is band sizes 28-40 and cup sizes A-E, it would seem that they are out of the range. But if they print off the 38E pattern pieces and take an inch away from the band then they will have made that pattern a 36″ band. However, now the cups aren’t an E anymore because the band is now smaller. With that one change the pattern has been converted into a 36F.

You can go the opposite way as well! For example, when using this Fenway pattern by Orange Lingerie I know that I’m a 40DD, but I didn’t want to buy the smaller pattern size set for the Marlborough pattern because I already had the larger size set, which includes a 38DDD. By printing that and adding an inch to the band I turned the whole pattern into a 40DD! LIKE MAGIC! I plan to make it up this Saturday in class, so stay tuned for the results!

If you want to see sister sizing in action, check out my “Bra Adjustment” highlight on Instagram! You can watch me “um” and “like” my way through this pattern adjustment I made on the Marlborough Bra by Orange Lingerie.