To alter pants, remove the stitching in the back-center seam, pin the edges so they fit the wearer, and sew the seam back together. Trim off the excess as you sew. You need a seam ripper, scissors, a fabric pencil or fabric chalk, straight pins and a sewing machine.
- Prepare the pants for adjustment
If necessary, remove the belt loop above the back-center seam. Remove the stitching from the waistband facing, and then remove the stitching from the center seam almost all the way to the crotch. On the inside of the pants, mark the placement of the new seam. Make sure the line of the placement is curved.
- Check the adjustment
Use pins to secure the new seam, and then baste the seam in place. Have the wearer test the pants to make sure they fit. If the crotch is baggy, open the inseams 10 inches down from the crotch. Mark a new seam so it tapers into the old one, narrowing the legs. Pin and baste the seam.
- Sew the new seams
Remove the basting along the inseams, and stitch the inseams along the new seam lines. Trim the excess. Reattach the crotch seams with a stretch stitch. Make a second row of regular stitching 1/8 inch closer to the cut seams, back stitching the beginning and end of each line. Trim the excess, and adjust the waistband to match the new seam. Sew on the belt loop if necessary.