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Zipper flys are very popular in ready-to-wear (rtw) clothing. They are very easy to install. If you follow these directions, you will construct a fly that no one will know is home sewn.


  1. Cut your pants fronts.
  2. Sew any darts or pleats.
  3. Mark the center front line on your pants pieces; this line is marked on your pattern pieces.
  4. Sew the fronts together along the center front line. From the bottom of the zipper down, sew with a regular stitch. From the bottom of the zipper and up, use a basting stitch. The point here is to baste your fly shut. A short stitch will make it more difficult to rip out later.
  5. Place pants fronts on table, wrong side up. Fold both fronts to the left, leaving one fly extension pointing to the right. Pin zipper in place, with side lining up to center front. You will be sewing the side furthest from center front.
    Zipper Fly Step 2
  6. Use a zipper foot to stitch close to the zipper on the side sticking out from the pants fronts.
    Zipper Fly Step 3
  7. Turn zipper over. Fold the extra fabric down under the zipper. The extra fabric may extend under center front. Pin and stitch about 1/8 of an inch (1 mm) from zipper. This holds that extra fabric in place.
    Zipper Fly Step 4
  8. Use zipper foot to stitch close to the zipper.
    zipper fly step 5
  9. Flip pants so that pants fronts are both on your right. They were on the left.
    Zipper Fly step 6
  10. Turn zipper over. Make sure that it’s flat.
    Zipper Fly step 7
  11. Pin zipper to the fly extension on your left.
    Zipper Fly Step 8
  12. Using a zipper foot, sew close to the zipper.
    Zipper Fly Step 9
  13. Now your zipper is attached to both fly extensions, but no sewing shows on the front of the pants.
    Zipper Fly Step 10
  14. Turn pants over so they are right side up.
    zipper Fly step 11
  15. Butt fly template against the center front seam. If you don’t have a fly template, you can copy one from a pair of pants.
    Zipper Fly step 12
  16. Trace around fly template.
    Zipper Fly Step 13
  17. Pin pants front to the fly extension underneath. Make sure everything is nice and flat and smooth.
    Zipper Fly Step 14
  18. Using your usual foot, sew fly stitches in place. Note: I always start at the bottom. If I start at the top, I tend to twist the fabric.
    Zipper Fly Step 15
  19. Hey, it looks like a fly!
    Zipper Fly Step 16
  20. Press.
    Zipper Fly Step 17
  21. Admire your fly.
    Zipper Fly Step 18
  22. Admire your fly some more. But wait; something is missing!
    Zipper Fly Step 19
  23. Cut a piece of fabric 4×8 inches (10 x 20 cm) for the fly shield.
    Zipper Fly Step 20
  24. Fold Fly Shield in half, wrong sides together.
    Zipper Fly Step 21
  25. Press.
    Zipper Fly Step 22
  26. Do you see the difference between the pressed fly and the unpressed fly in step 24?
    Zipper Fly Step 23
  27. Overlock the edges of the fly shield. Optional, cut off some fabric from the bottom to form a curve. There’s nothing wrong with a rectangular fly shield. If you don’t have a serger, you can overlock with your sewing machine. Use your overlock foot and a zigzag stitch.
    Zipper Fly Step 24
  28. Pin your zipper shield to the extention on the underlap side of the fly.
    Zipper Fly step 25

  29. Fold your pant fronts off to the side, so that you only sew thru the fly shield and extension.
    Zipper Fly Step 26
  30. After you’ve sewn the side of the shield to the extension, tack down the bottom on the opposite extension. This is optional, but it will keep your fly shield from flopping around.
    Zipper Fly step 27
  31. Admire your fly shield.
    Zipper Fly step 28
  32. Admire your fly from the wrong side.
    Zipper Fly step 29
  33. Admire your fly from the right side.
    Zipper Fly step 30


  • Use polyester or nylon zippers. If you use a metal zipper, it is much more difficult to trim to size.


  • Don't forget to press as you go. It makes a huge difference in the quality of your work.

Things You'll Need

  • Pants pattern with fly
  • Pants fabric
  • Zipper (7 inch/20 cm)
  • Tracing material (e.g. paper) to make your fly template
  • Chalk or other fabric marker
  • Sewing pins and thread
  • Sewing machine
  • Iron
  • Serger (optional)

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Comment by Mary Ann Brensel on April 21, 2010 at 8:05pm
I wouldn't have attempted a fly without this tutorial. Patterns just don't give enough directions to do it right. Thank you for taking the time to create such a professional tutorial.
Comment by Bonnie Anderson on April 21, 2010 at 9:19am
Thank you for a great detaied tutorial! Never done one, not so intimidated now!
Comment by Sadie on April 21, 2010 at 8:45am
Neefer, thanks so much for the tutorial! I'm the kinds that think adding a zip to a purse is extremely hard... you can only imagine what I think about the fly!

Your tutorial makes it sound quite easy... Thanks again!
Comment by Mary on April 21, 2010 at 6:25am
excellent tutorial!

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