Most people have a closet full of clothing, some of which does not fit properly. While you can certainly get rid of pieces of clothing that are too large or small for you, it is sometimes a better idea to alter what you have to fit your current body shape. While dress shirts are considered by many seamstresses to be one of the most difficult and labor-intensive projects to sew, a ready-made dress shirt is surprisingly simple to alter.
Turn the dress shirt inside-out and put the shirt on with the seams facing outward.
Pin the excess fabric on the side seams of the dress shirt, beginning at the waistline and working from that point. Taper the new seam adjustment toward the sleeve seam that sits under the armpit if no alterations are needed to the sleeve or armpit area. Taper again toward the bottom hem if no adjustments are required in the width of that area.
Measure both of the side seams with the sewing tape measure to be sure that you are making even alterations on both the left and right side seam. Adjust the pins if the measurements are significantly off. Remove the shirt.
Stitch the new side seams with your sewing machine, stitching from the armpit area to the hem and removing the straight pins used to mark the new seam before the sewing machine needle runs them over and breaks.
Turn the dress shirt right side out and try it on to visually check that the changes are what you had in mind. Adjust the side seams until the alteration is even and acceptable. Repeat Steps 1 through 4 if the side seam needs further attention. Trim the excess fabric on the inside of the shirt with your sewing scissors and finish the raw edges using your preferred method.
Remove any excess fabric on the sleeves of the ready-made dress shirt. Wearing the shirt inside out, pin both sleeve side seams evenly to remove the excess fabric in this area. Taper the new seam toward the cuff of the dress shirt. Remove the shirt and stitch the new sleeve side seams on your sewing machine. Trim the excess fabric and finish as desired.
Shorten the hem of the dress shirt. Measure the desired length with your sewing tape measure, leaving an extra 1/4- to 1/2-inch to be used as a hem allowance. Mark the new hem length by measuring at even points along the existing hem with the tape measure and placing a pin above the old hem line at the desired distance. Follow the previous curve of the existing hem. Trim the old hem off the ready-made dress shirt following the marks made. Sew a narrow rolled hem on your sewing machine by folding the raw edge of the hem over 1/8 to 1/4 inch and then folding the fabric over again to cover the raw edge. Stitch close to the edge of the double-folded hem.
It may be possible to add width to your dress shirt as well if the shirt has a large enough seam allowance. Gently cut away the threads in existing side seam and re-sew the seam allowance closer to the edge. Adding a back or breast dart can further shape the dress shirt. More complex alterations are also possible such as shortening a cuffed sleeve or adjusting the collar. These techniques will require you to deconstruct the shirt more fully and, hence this project is best left for skilled tailors.