https://www.cutoutandkeep.net/projects/waist-pants-into-a-skirt • Posted by Elizabeth A.
The "before" picture.
Determine how long you wish your skirt to be. Cut off the excess length on legs. Allow a couple of extra inches for the hem.
Rip out inside leg seams and front and back seams. I ripped out the seams up to the yolk. If your pants have no yolk, leave seam intact about 6 inches down from waist (both front and back).
Turn whole thing inside out. Sew up front and back seams. In this example, my seam roughly follows the green stripe. Trim off extra fabric and zig-zag rough edges to prevent raveling.