Sewing Blog

Sewing Pants 101: How to Sew a Fly-Front Zipper

Applying zippers when making clothing, for some, can be an intimidating task. There are indeed many different types of zipper applications that every good sewer should know — invisible zippers, lapped zippers, railroad zippers and the popular exposed zipper.

However, while all require different techniques, none are truly difficult, even sewing zippers, once you learn all the right steps to making them look perfect.

fly front zipper

The same can be said for the fly front type of zipper that is common in many trouser style pants, jeans especially. The key to applying a pants zipper is to buy one that is longer than the opening it is intended to fit.

The key to applying a pants zipper is to buy one that is longer than the opening it is intended to fit.

In fact, this is a good rule to follow for most zipper applications. One of the most difficult steps to inserting any zipper is sewing close to the zipper tab mechanism. By choosing a longer zipper that dilemma can be completely avoided, producing straighter lines which give any garment a more professional finish.

Believe it or not, applying a fly front zipper is among one of the easiest zippers to sew. Mostly because much of the actual sewing is done behind the scenes, out of sight of the public side of the garment. Furthermore, those initial stitching steps help to guide the final, visible stitching to make the zipper lie flat and look clean and well sewn.

Mastering in Minutes: Zippers

Intimidated by zippers? Don’t be!

Craftsy expert Callie Works-Leary takes you step by step through 3 zipper insertions so you can properly prepare the seam, place the zipper and stitch it for a professional appearance. Get the Tutorial

Follow these steps to learn how to sew a fly-front zipper with precision...

Step 1:

Purchase a standard zipper that is longer than what’s called for in the pattern or that measures 1-2 inches longer than the zipper opening.

Step 2:

Cut two pieces of fusible interfacing that will cover both sides of the zipper flaps. The interfacing should extend from the center front to the flap edge. Press or fuse the interfacing to the underside of the zipper flaps.

apply fusible interfacing to flaps

Step 3:

Stitch the two pant fronts together using a 5/8” seam allowance starting midway into the crotch curve to where the base of the zipper is located.

Note: You start midway into the crotch curve instead of at the beginning of the seam so the inseams and crotch seams can be stitched in their proper sequence.

Use a regular stitch length and backstitch at the zipper base location. Then continue to stitch along the center front using a basting stitch.

baste stitch along center front
Step 4:

Clip into the seam allowance up to the stitching line right at the base of the curve. Now press the flap seam open.

clip to stitching at base
Step 5:

With the public sides of the pant fronts facing each other and the left side of the zipper flap lying flat, lay the zipper, upside down, along the center front seam as shown in the photo with the bottom of the zipper positioned at the base of the curve.

lay zipper along center front seam
Step 6:

Pin the zipper in place as shown and then stitch it in place close to the zipper teeth using a zipper foot. Turn the zipper over so the front side of the zipper is revealed. Now stitch the zipper again 1/8” from the fold. This stitch will show when the zipper is opened, so it should be carefully done.

stitch zipper to flap stitch along fold

Step 7:

Now flip the pant fronts so the underside of the zipper if facing up and both pant fronts are facing each other. Lay the zipper flat onto the free zipper flat. Allow the zipper to fall into place naturally. Pin the unstitched side of the zipper in place.

lay zipper flat onto flap
Step 8:

Stitch the zipper to this flap anywhere within the zipper leg.

stitch other side of zipper to flap
Step 9:

Next, turn the pants to the public side as shown. The zipper should lie flat on the work surface.

open pant front, mark zipper base

Step 10:

Mark the position of the zipper base or end with a pin. Next, mark the final stitching line with chalk or a marking pen, so it is 1 ¼” from the center front seam. Mark the bottom curve as well making sure to avoid the zipper base.

mark stitching line
Step 11:

Following the marked line, sew the final stitching line. Lastly, undo the center front basted seam.

sew final stitching line

Mastering in Minutes: Zippers

Intimidated by zippers? Don’t be!

Craftsy expert Callie Works-Leary takes you step by step through 3 zipper insertions so you can properly prepare the seam, place the zipper and stitch it for a professional appearance. Get the Tutorial

10 Comments

Marianne

Fitting a zip in trousers, well that’s a bit daunting, I have never done it but I am shortly getting some fabric and using these instructions I will have a go. Others zips including invisible ones are easy. Thanks for the tutorial I will give it a go.

Reply
Frances

I’m confused. If the zipper is 2 inches longer than the fly opening what happens to the surplus zipper that extends beyond the waist seam?

Reply
Linda Reynolds

Once the zipper insertion is complete and you are ready to apply the waistband, lower the zipper tab so it below the waistline seam (or, into the body of the pant front). The extended zipper legs can now be trimmed down to the waistline edge. Or — insert the waistband in the normal process, then trim off the excess zipper. Just be sure the zipper tab had been lowered into the body of the pant. If you trim off the zipper tab or you will render the zipper unusable.

Reply
Marylea M

Frist time for a fly zipper it went very good for me. We all understand instructions differently, these worked perfectly with my thought process. Thanks for sharing. Now on to finishing the pants

Reply
Linda Reynolds

Glad you found them helpful. I find this a fun and easy zipper to install once you’ve done it a few times. Thanks for reading the post.

Reply
Bonnie Spielman

What a great tutorial! With these instructions I think, no I know, I will not be too intimidated to try it.Thank You, thank you, thank you!

Reply
carol koch

Thank you for these wonderful directions. The directions on the pattern for the slacks I’m making were terrible. My fly zipper came out beautiful!

Reply
PANTS | The Sewprano

[…] exactly have room to play around a lot.  I also sewed my first fly-front, using mostly this tutorial, and it was vastly easier than I […]

Reply
norm

I have a new pair of route 66 100% polyester mens medium pants they have a elastic waist line and a lose inside netted lining id like to make the front a opened hidden of secret to the inseam where the sowing meets the leg inseam in the crotch area a snap type closure I should of bought 2 pairs then id have more material to match the material im a upholsterer and do 100% hand sowing on antics and don’t have a sowing machine right now any helpful ideas would be great

Reply

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