Your underbust is the primary support for your bust, and is the anchor for your bra.
When your bra does not provide enough firmness and support for your underbust the back becomes looser, rides up, and your breasts sag. When taking your size remember that all bras, old and new, stretch out over time and wear.
Different materials may also affect your bra size
A bra made of a different material to what you normally wear can also alter your back size. For example, a bra with a power mesh in the back wings is usually firmer than a lace back bra. Designers try to account for this but results can vary.
Sizing yourself while wearing a bra?
Be sure to fasten it on the loosest, or middle, hook. If you can comfortably fasten it on the tightest hook, try going down a back size. Here are 2 easy rules of thumb to remember:
- If you go up a back size, then go down a cup size.
- If you go up a cup size, then go down a back size.
For example if you wear a size 10 top with a 14D bra, try a 10E or a 12DD (amazingly, these are all the same cup size!)
Use the cross fitting chart below to find other sizes that may be suitable for you (according to the rules stated above).