Definition
A full bust adjustment, or FBA, is a pattern alteration that adds width and length over the bust for a larger cup size, without enlarging the shoulders or waist.
Standard sizes assume a particular cup size, often a B cup for the large pattern companies and a C cup for some independent designers. If your bust is fuller, choosing the size by your full bust makes the shoulders, neck and armholes too big; choosing it by your high bust fits well above, but leaves too little room over the bust, with pulling, a front hem that rides up and darts that end too high.
The FBA solves this. You choose the size by your high bust, measured above the bust and under the arms, and then add the missing room. The usual method on a bodice front with a dart:
- Mark the bust point and draw lines from it to the armhole, to the hem and into the side dart.
- Cut along them and spread the piece by half the difference between your full bust and the pattern's bust measurement.
- The side dart grows deeper, and the center front grows longer to cover the bust.
- True the edges and the dart legs.
An FBA can also be made on a princess seam, by adding to the side panel, or on a dartless top by creating a dart. A small bust adjustment does the reverse.
Patterns drafted from your own measurements start from your body rather than a standard cup, which often reduces the need for one. More in full bust adjustment explained.