Hemming a pair of dress pants is no longer a mystery. Karen Schmidt demonstrates step-by-step what is needed to get professional looking results. Measure the length that you would like to trim and pin the new hemline in place. Use an iron to mark the new pant length with a crease. Then unfold and rip the seam out of the original hemline. Cut away excess fabric sew a protective zigzag seam along the trimmed fabric. Refold the new creased hemline. With a matching thread, sew a single line to hold the new pant length in place.