Small Bust Adjustment

Not all curvy and plus size sewists have big boobs—far from it! We all have different bodies with different proportions, and if you're smaller than a B or C cup, you may need to do a small bust adjustment. Here is our complete guide for how to do a SBA.

What is a small bust adjustment? 

A small bust adjustment, also know as an SBA, removes width and length in the front (where your bust is) without altering the back or sleeves, so that the garment still fits you everywhere else. 

How do I know if I need an SBA? 

Key indicators of needing an SBA are excess or saggy fabric around the bust. If a pattern offers both high bust and full bust measurements, and your full bust is smaller than the full bust measurement that corresponds to your high bust, that could also clue you in to needing an SBA.

It's always worth checking the finished garment measurements of your pattern first before starting your SBA. You may not need to do an SBA on garments that are designed with a lot of ease in the bust (ultra-flowy tops or dresses) because they're meant to be loose in the bust. Knit garments that have negative ease and stretch over the bust may also fit you fine without an SBA.

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 SBA in commercial patterns, it's safe to assume you'll need to do an SBA for any new pattern that you try. If you're using a Cashmerette pattern, be sure to start with the smallest cup size (C/D) so that you're minimizing how much of an SBA you need to do, if at all.

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 as well as 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 SBA? 

The process for doing an SBA varies depending on the pattern you're using. Here are step-by-step tutorials for how to do an SBA on different pattern types: