Bust Adjustment Tools
The most common fitting adjustment in sewing. If the pattern pulls across the bust or has excess fabric there, one of these tools will calculate the exact fix for your pattern style.
Full Bust Adjustment (FBA) — Darted
Pattern pulls across the bust? Calculate the exact slash-and-spread amount for darted bodices.
Full Bust Adjustment (FBA) — Princess
Same FBA calculation for princess-seam patterns — spread the side front without darts.
Small Bust Adjustment (SBA) — Darted
Excess fabric at the bust? Calculate the overlap amount for A cup and smaller.
Small Bust Adjustment (SBA) — Princess
Overlap the side front and flatten the CF curve for smaller busts on princess-seam patterns.
Which tool do I need?
FBA (Full Bust Adjustment) — your bust is larger than the pattern's intended cup size. The fabric pulls horizontally across the bust and the front hem rides up.
SBA (Small Bust Adjustment) — your bust is smaller than the pattern's intended cup size. There's excess fabric at the bust and the dart is too large.
Darted vs. Princess — choose based on your pattern's construction. Darted patterns have a side-seam or waist dart; princess-seam patterns have a vertical seam through the bust area instead.
How bust adjustments work
Pattern companies draft for a B or C cup at each size. If your cup size differs, the pattern won't fit at the bust regardless of which size you cut. An FBA or SBA adjusts the bust area without changing the rest of the pattern.
The adjustment is done by slashing the pattern piece through the bust point and spreading (FBA) or overlapping (SBA) the pieces. The calculator tells you exactly how much to spread or overlap based on the difference between your bust measurement and the pattern's.