Most sewing patterns are designed for a B-cup bust, so what should you do if you're bigger than that? A full bust adjustment! Here is our complete guide to help you figure out if you need an FBA, and how to do one.
What is a full bust adjustment?
A full bust adjustment, also know as an FBA, is one of the most common pattern adjustments that curvy and plus-size sewists need to make. This adjustment adds width in the front (where your bust is) without altering the back or sleeves, so that the garment still fits you everywhere else while giving your bust the room that it needs. That way you, don't have to size up the entire garment, which can result in shoulders that are too wide, a neckline that gapes, or a whole host of other fit issues.
How do I know if I need an FBA?
There are several ways to tell if you're going to need to do an FBA. First, if you know what cup size your pattern is drafted for, and you're larger than that cup. Second, if your pattern's size chart includes both high bust and full bust measurements, but your full bust measurement is larger than the full bust measurement that corresponds to your high bust measurement. Finally, if you sew a muslin and there is tightness in the bust, the fabric is pulling forward at the front armhole, or there are lines radiating from the bust.
It's always worth checking the finished garment measurements of your pattern first before starting your FBA. Garments that are designed with a lot of ease in the bust (ultra-flowy tops or dresses) may have enough room to fit your bust without needing to add additional width.
Cashmerette Patterns come with cup sizes C-H, which means that many busty sewists don't have to do an FBA! Consider using a specialized pattern with multiple cup options to avoid having to make this adjustment.
Do I have to make a muslin?
It's always a good idea to make a test garment before starting your fit adjustments, but if you regularly have to do an FBA in commercial patterns that aren't specialized for larger busts, it's safe to assume you'll need to do an FBA on any new pattern you try.
When making your muslin, be sure to use a fabric that is similar in weight, drape, and stretch to your final fabric. Confusingly, sometimes the fabric called muslin is suitable for your muslin (test garment), but often it's not!
What supplies do I need?
You'll need the pattern you're working on, tracing paper, scissors, a pen, and some tape. You'll also want to clear off a flat surface to work on so that you can lay your pattern pieces flat. We always recommend tracing your pattern pieces on tracing paper (such as Swedish tracing paper or tissue paper) beforehand so that you can always refer back to your original piece if needed. Once you cut into the real thing, there's no going back!
How do I do an FBA?
The process for doing an FBA varies depending on the pattern you're using. Here are step-by-step tutorials for different pattern types:
- How to calculate the size of your FBA
- How to do an FBA on a darted or dartless bodice
- How to do an FBA on a knit bodice
- How to do an FBA on a princess seam bodice
Want to learn more?
Watch curvy sewing expert Jenny Rushmore identify and fix a variety of upper body fit challenges in 21 clear and easy-to-follow video lessons.
If you're busty, Jenny's Craftsy course is a one-stop shop for all things FBA! Learn how to do an FBA on many different pattern types.