We have plenty of Full Bust Adjustment (FBA) tutorials on Helen’s Closet, but you know what is missing? An FBA tutorial for swimsuits and knit fabrics! So we are here today to remedy this. This blog post is written specifically for our latest pattern—the Sunstar Swimsuit, but the directions will apply to any other knit pattern like our Dawson Top.
Grab Sunstar on sale this week for 25% off! No code required. Sale ends July 17th, 2024.
First, how do you know you may need an FBA on your Sunstar? You may know you need one because you always need an FBA. If you’ve already made a Sunstar and experience any of the following, you will likely benefit from an FBA:
- it feels tight across your chest
- it's gaping open at the front
- it's gaping open at the front seam (on one piece)
- the top hem is hiking up (on separates), or
- the armscye is dragging to the front
You Will Need:
- Top front pattern piece (1)
- Top back pattern piece (2)
- Extra paper
- Pen or pencil
- Tape
- Paper scissors
- Ruler
How Much Should I Add?
You will need to add room both vertically and horizontally. To calculate how much vertical length to add, make a toile of the swimsuit and measure how much the hem/waist seam is riding up. If you have already made a Sunstar Swimsuit, take this measurement on the existing swimsuit. Write this measurement down, and it will be your adjustment distance.
The horizontal distance is an estimate, and we recommend adding around ½”-¾” (1 cm - 2 cm) for cup sizes over D.
If you want to make a version without making a toile and suspect you will need an FBA, you can do your usual FBA amount vertically. If you are unsure, try adding ~1” (~2.5 cm) to the height to see how it goes.
Flat Pattern Adjustments
We will start by adding new notches on the top front (1) and top back (2) pattern pieces. Draw the new notches ¾” (2 cm) away from the top on both front and back top pattern pieces. At this point, you are done with the top back pattern piece so you can put it away.
On the top front pattern piece, draw a horizontal line through the widest part of the bust. The easiest way to ensure the line is horizontal is to make it perpendicular to the grainline. Cut the pattern piece apart at this line.
Place a piece of paper underneath the top of the front top pattern piece and tape it down. Draw a line parallel to the bottom of the top, the adjustment distance away. Draw an extension of the grainline as well. It will help with lining the pieces up in the next step.
Line up the bottom part of the top front to the adjustment line. Line up the grainline on the bottom part of the pattern to the extension of the grainline you drew in the previous step. Tape the pattern piece down.
Draw the new front edge, blending the line into the original edge. Add ~½” -¾” (1.3 cm - 1.9 cm) at the widest part of the bust on the side seam and draw a new side seam.
Sewing
The construction steps are almost identical. The only difference is sewing the side seams on the main fabric and lining.
In step 4, with the right sides together, line up the new top notches and the old side notches on the front and back. Place pins at the notches, leaving the part between the notches unpinned. The top front side seam will be longer than the back.
Stretch the back when sewing the side seam to fit the front. This will create a ruching effect needed to accommodate extra cup volume.
Repeat for the other side and lining pieces. Proceed to step 6 and sew the rest of the swimsuit.
Tag us on Instagram and let us know how your FBA on the Sunstar works out!
