It’s easy to adjust princess seams by moving the bust point and increasing bust size in a princess seam-style bodice pattern.

The step-by-step process starts with making sure the natural bust point is in the right place on the pattern. You can double-check this by making a test garment or muslin.

Adjust the bust point level

Change the bust point level on the bodice pattern’s side panel by drawing and cutting away a box around the bust point area. Slide the box up or down, depending on whether the newly marked natural bust point is lower or higher than what is printed on the pattern. Tape the box in place and add pattern tissue behind it.

Blend the new seam using a French curve or fashion ruler. Repeat this process for the bodice pattern’s center panel.

This method follows the same one for adjusting a side bust dart, as shown in “Moving Darts to Improve the Fit.”

Alter for a full bust

To accommodate a full bust, you need to add length and width to the bodice pattern.

First, try on the muslin. Release the princess seam between the bust curve notches, if it is too tight, and measure the gap. You’ll transfer this amount to the bodice’s side front panel by drawing and cutting three adjustment lines.

Draw the following lines:

•. Vertical from the bust point to the hem

•. Angled from the bust point to the armscye

•. Angled from the bust point to the side front seam.

Cut along the lines, leaving a hinge at the armscye and bust point. At the waistline, cut from the vertical line to the seam and set this section aside. Then spread the side front panel lengthwise and widthwise to the gap measurement taken on the muslin. Tape…