The Full Bust Adjustment on a Pattern

A larger cup means the bust projects further and needs more fabric to travel over it, both in width and in length. But cup size is largely independent of frame size, so a person can have narrow shoulders and a fuller bust. Grading the whole pattern up to gain bust room also enlarges the shoulder, neckline and armhole, which were already correct, producing a garment that gapes at the neck and slips at the shoulder.

The FBA targets the problem precisely. It adds fabric where the bust needs it and nowhere else, so the frame stays put while the bust gains room. This is why it is preferred over sizing up for anyone whose bust and frame are not the standard proportion.

• Width across the bust, so the front is not tight side to side.
• Length over the bust, so the front hem does not ride up at center front.
• Additional dart intake, because a larger cup needs a deeper dart to build the shape.
• All three added together at the bust apex and nowhere else on the frame.
• No change to the shoulder width, neckline or armhole circumference.

1. 1.Mark the bust apex on the front pattern piece.
2. 2.Draw three slash lines: from the armhole to the apex, from the apex down to the hem, and from the apex into the existing dart.
3. 3.Cut along the lines, leaving small hinges of paper at pivot points.
4. 4.Spread the pieces apart by the amount of extra width needed, which opens the dart and adds length.
5. 5.Fill the gaps with paper and true all the edges.

Spreading the pattern deepens the existing dart and often creates a second opening that becomes extra dart intake or added length at the hem. This new fullness has to go somewhere: it can stay as a larger bust dart, be split between a side dart and a waist dart, or be rotated into a princess seam. The choice depends on the design.

The extra length that appears at the front hem must be trued so the center front and side seam are level again, or the hem will step. Because the side seam gains length from the spread, you also re-walk it against the back side seam to confirm they still match.

On a darted bodice the FBA opens and deepens the darts, which is the most direct route. On a princess-seamed pattern the same adjustment is made by adding width and length to the side front panel through the bust region, effectively an FBA expressed inside the seam rather than in a dart. Both achieve the same thing: more room and shape over the cup.

The princess route is often cleaner for large adjustments because the extra shaping distributes along a curved seam rather than piling into one deep dart, which can pucker if it becomes too large.

The FBA is fundamentally a workaround for standard sizing, which assumes a fixed cup. When a pattern is drafted from an individual's actual bust and frame measurements, the cup room is built in from the start and no adjustment is needed. Minerva Patterns drafts to personal measurements and supplies the result as DXF AAMA, PLT and PDF, so the bust fit is correct on the first draft rather than adjusted after the fact.

Even so, understanding the FBA is essential for anyone adapting existing patterns, because it reveals exactly how bust shaping is built and how much fabric a cup truly requires.