When two bras have sister sizes, it means they share the same amount of the volume in the bra cups, but different band lengths. Here's the ultimate guide to sister sizes by Understance.
What Are Bra Sister Sizes and Why Do They Work?
What Are Sister Size Bras and How Can They Make for a Better Fit? – WanderWoMom
Sister Sizing Bra Sizes and How Do Bras Sizes Work & Bras Sizing Explained
How to Find Your Bra Size: The Easy Guide - Our Fashion Garden
Bra Sizes Explained – Sugar Candy
Bra Sister Sizes - How & Why They Work
Finally, Bra Sizes Explained – Understanding How Bra And Cup Sizes Work – ThirdLove
Understanding Bra Sister Sizes
How to Determine Your Bra Sister Size for Better Plus Size Bra Fit
Bras 101 Blog - Sister Sizes
Bra sister sizes UK Discover your next best bra size! – Bra Size Calculator