How to alter a men's suit jacket

Updated July 20, 2017

Does someone you know need his suit for an event but finds it doesn't fit as it once did? Alterations are the solution, but they should not be attempted if you have little sewing experience. If you are confident in your ability, you can make most necessary alterations in the hems and the back seam. All alteration markings should be made while the jacket is on the person.

Using a seam ripper, carefully rip out the stitching that connects the lining to the sleeve and jacket hems. This gives you access to the seams you need to adjust.

With the jacket on, check the fit of the back seam. If the jacket hangs too loosely when buttoned, take in additional seam allowance in the back seam. Do not take in the same amount from top to bottom, but instead adjust the fit by pinning the back seam so the jacket hangs properly. If the jacket is too tight, open the back seam and pin the seam using at least a 6 mm (1/4 inch) seam allowance. Mark the adjustments with tailor's chalk on both sides of the seam on the outside of the jacket.

Turn the jacket inside out with the lining free. Pin the seam according to the markings, with the right sides together. Look at the back of the jacket. Your chalk lines should meet and be almost invisible. Baste the seam and try on to check the fit. If it isn't right, carefully remove the basting and repeat the process.

When your fit is correct, stitch the altered seam on your sewing machine. Carefully remove the original stitching and finger-press the seam open. If you've taken up the seam, don't trim extra seam allowance in case you need to let out the jacket later.

Try on the jacket and adjust the jacket hem. The bottom edge of the jacket should just rest in your curved fingers when your hands are at your sides. Pin the hem to the correct length. Stitch the hem by hand.

Using the same technique as for the jacket hem, adjust the sleeve length and pin. Sleeves should come approximately to where your thumb meets your wrist. If you have more than 5 cm (2 inches) of hem, trim the hem allowance to 5 cm (2 inches). A bigger hem will not hang properly. Stitch the hem by hand.

Carefully reattach the lining to the hem edges. The edge of the lining should end approximately 1.2 cm (1/2 inch) from the hem edge and should not pull tightly from the top of the jacket. It is best to pin the lining in place while the jacket is on. Hand-stitch the lining in place.

Have the jacket professionally cleaned and pressed to remove chalk and alteration marks.

Things You'll Need

  • Seam ripper
  • Tailor's chalk
  • Pins
  • Hand needle
  • Sewing machine
  • Thread
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About the Author

Jean Breeding is a freelance writer in Knoxville, Tenn. She is a former high school English teacher and has participated in writing seminars for teachers in Tennessee and South Carolina. She recently completed coursework to become a certified technical writer. Demand Studios is her first professional writing venture.