Introduction to bust adjustments
Let’s talk about bust adjustments! What are Full Bust Adjustments (FBA) and Small Bust Adjustments (SBA), and how do I know if I need to do one?
WHAT IS A FBA AND SBA?
Most sewing patterns are constructed assuming a B cup on all sizes. Measure your upper bust (A) and full bust (B) to figure out your cup sizes. Remember to wear a bra when measuring. Your cup size is full bust minus upper bust:
If the number is:
+ 2,5 cm = A cup
+ 5 cm = B cup
+ 7,5 cm = C cup
+ 10 cm = D cup
WHEN DO I NEED AN FBA/SBA?
Technically, when your cup size is larger than B you’d need an FBA, which is an adjustment in the bodice to make it fit better. If your cup size is less than B you’d do an SBA, which is a similar adjustment, but would make the bodice smaller.
If you’re sewing a knit garment, such as the Linnéa top, you may not need to do an FBA or SBA. The bust adjustment is mostly needed for woven garments. The knit fabric will stretch and move with your body, and it will also naturally form drag lines depending on the position you’re in. The fact that knit fabrics are so easy to fit is one of the their advantages.
If you feel that you may need an FBA/SBA we recommend you to first sew a toile in your size without adjustments. If you’re not quite happy with the fit then an FBA/SBA could be for you.
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>> How to do a quick, "cheat" FBA or SBA?