First up, I found this blog post from The Shapes of Fabric with instructions on working out the size of the flounce. I measured the neckline of the crop top to determine the perimeter of my circle, used that to work out the radius (Radius = Perimeter÷∏÷2), and then used a compass to measure the circle onto my tracing paper.
I decided I wanted my flounce to be about 6 inches, so I measured another circle 6 inches from the perimeter of my inner circle. After doing that, I realized I actually wanted more length at the front and less at the sides, so I made a 1″ mark at the center front and adjusted the circle (see red line).
Once I had my circle made, I cut it in half (at the fold line). I then overlayed my crop top front with the circle, drawing a line to match the curve and then cutting it away. I also made a mark on the crop top front so I knew where the flounce would hit.
If you’ve done this correctly, the center curve of the flounce will exactly fit the crop top neckline. I basted it on with a zig zag stitch before adding binding to the edges. And because swim doesn’t fray, I did not hem the edges of the flounce. If you felt so inclined though, you could do a narrow hem with wooly nylon thread and a serger/overlocker.
Happy sewing! ❤
Disclosure: I’m a Jalie Patterns Creative Ambassador and received this Jalie pattern complimentary for purposes of review and promotion.