Today we are going to walk you through how to do a Full Bust Adjustment (FBA) on a princess seam bodice. It is a bit more involved than an FBA on a darted bodice, but it is totally doable and so worth it. Before you know it, you will be a pro when it comes to doing an FBA on a princess seam bodice.
This tutorial uses our Lockhart Jumpsuit and Dress as an example. You can find that pattern here:
Which Size Range to Use?
Use your high bust measurement to pick the size from the size chart. Then compare your full bust measurement to the full bust measurement listed for the size you picked. For sizes 12-22, there is an overlap in the size range where you may be able to use the D-cup range to get the fit you need.
If you are smaller than a size 12, use the B-cup size range pattern in your size to do an FBA.
If your full bust measurement is bigger than the full bust measurement in the D-cup size range, then use the D-cup size range pattern in your size to do an FBA.
Calculate Adjustment Amount
To get the adjustment amount, calculate the difference between your full bust measurement and the full bust measurement of the size you chose. Divide the difference by 2. This is the adjustment amount you will need to add to your pattern pieces. Write this number somewhere so you remember it.
Pattern Pieces and Tools Needed
For the FBA on the princess seam bodice, you will need the Center Front Bodice (1) and the Side Front Bodice (2) pattern pieces.
You will also need lots of spare paper since you will need to trace the pattern piece twice. You will also need tape, a pencil or pen, paper scissors and a ruler.
Princess Seam FBA
1. On the Side Front Bodice (2), draw in the ⅝” (1.6 cm) seam allowance around the front panel seam and partially at the armscye seam.
2. Draw 3 lines as follows:
Line 1: horizontal line across the pattern piece at the apex. This line will go right through the middle notch on the panel seam. The easiest way to make sure this line is horizontal is to make it perpendicular to the grainline marking on the pattern.
Line 2: goes from the apex at the panel seam line to the waist seam. Angle this line slightly so that it crosses the waist seam behind the panel seam line.
Line 3: goes from the apex at the panel seam line to the corner on the armscye.
3. Starting at the bottom of the pattern piece, cut through line 2 up to the apex. Pivot and continue cutting along line 3 to the seam allowance. Snip into the seam allowance from the other side to create a hinge.
4. Starting from the side, cut through line 1 to the apex, leaving a hinge. If you accidentally cut through, that is okay!
5. Tape the upper piece (A) to a piece of paper. Move the front panel piece (B) out and the bottom piece (C) down, creating a vertical gap and a dart-like shape. Adjust the pieces B and C until the vertical gap where line 2 used to be (blue) has parallel sides and is the width you need for the FBA. Tape pieces C and the upper part of B down.
6. Draw a horizontal line (line 4) through the bottom of piece B (magenta) and cut through it. Move the bottom of the piece down so that it is in line with the bottom of piece B. Measure the length of the created vertical gap (gap 1) and write it down. Tape everything down.
7. Trace the adjusted Side Front Bodice, transferring all the notches, the dart, the new bust apex at the end of the dart and the top and bottom of the gap. Cut the new traced pattern piece out.
8. On the new pattern piece, draw a line through the bottom dart leg and through the new apex to the end of the pattern piece. Starting from the side seam, cut through this line to the new bust apex. Then starting from the panel seam, cut through the line to the other side of the new bust apes, leaving a small hinge at the new bust apex.
9. Swing the bottom piece B up towards A to close the dart. Tape it down. This will create a small gap (gap 2) at the front. Measure this gap and write it down.
10. Place a piece of scrap paper underneath gap 2, tape it down and draw a smooth line connecting the edges of the gap. Extend the original grainline from the bottom of the Side Front Bodice to mark the new grainline.
The Side Front Bodice is done! Next, we will transfer these adjustments to the Center Front Bodice.
11. Measure two distances on the new Side Front bodice piece and write the measurements down:
- Measure the first distance from the bottom of the pattern piece to the bottom of gap 1 (red arrow).
- Measure the second distance from the top of gap 1 to the bottom of gap 2 (blue arrow).
12. On the Center Front Bodice pattern piece, draw two horizontal lines. Line 1 (red) is distance A away from the bottom of the Center Front Bodice pattern piece, and Line 2 (blue) is distance B away from Line 1. Cut through both lines.
13. Place scrap pieces of paper underneath the bottom part of the upper Center Front Bodice (A). Tape it down. Place piece B gap 2 distance away from piece A. Tape it down. Finally, place piece C gap 1 distance away from piece B. Tape it down as well. Connect the distance between gaps with smooth lines.
Cut out your new pattern pieces and you are done! Walk the edges of the pattern pieces along the seam line to make sure everything was adjusted accordingly and the notches are lining up. As usual, when completing any adjustments to a pattern, we highly recommend making a muslin before cutting into a nice fabric.
