fly front zipper
Sewalongs, Sewing Tutorials


For a lot of people, the scariest thing about making jeans is the fly front. There are a lot of methods for installing them, and not all of them are easy to wrap your head around. I did a lot of research to find the best way to sew the Ginger Jeans fly, so hopefully these step by step photos will show you how easy it is to actually do.

Before we sew our legs together, we need to finish the fly extension of the left leg. The fly extension on the right leg will be trimmed off eventually, so don’t worry about it for now. Simply overlock or zig zag around the straight edge and as much of the curve as you safely can on your machine. When I’m serging, I try to fold the crotch curve out of the way and stop just before I reach the seam allowance.

finishing fly extension

Next, you will be sewing your two pant legs together at the front crotch seam. Starting at the center front notch, baste a straight line to the circle marking next to the bottom of the fly extension. You can draw a line with a ruler if this helps. You want a nice long stitch since you will be removing this stitching once your fly has been installed. When you reach the circle, switch to a medium stitch length, sew a few stitches, and backstitch just to the circle. Continue sewing normally along the 5/8″ seam allowance.

sewing fly front zipper

Now it’s time to cut a notch from the corner where your fly extension meets the regular seam allowance to the circle. Be careful not to cut into your stitching.

ginger skinny jeans pattern - installing fly front zipper-3

Finish that short crotch curve using an overlock or zig zag stitch – be sure to trim down to 3/8″. This is the one seam that must be finished this way, even if you are flat felling your seams. Also, I have to apologize for my horrible serging in the following photos. My serger was having major timing issues when I shot this tutorial. Please don’t judge me.

ginger skinny jeans pattern - installing fly front zipper-4

Press your fly extension open and your finished seam to the left on the inside.

crotch seam on jeans

Flip your jeans to the front, and sew two rows of double stitching to the right of the crotch seam, making sure your fly extension is lying flat and you finished seam is caught in the stitching.

edited: You can also sew just 1 row of topstitching along the crotch if you prefer the way it looks. Or, you can wait until your zipper is installed, go back and add the second row and stop sewing at the fly topstitching, finished off with a bar tack. It really is a matter of preference, so take a look at RTW pairs in your closet to see what works for you. I like the double line so that’s what I’ve called for in the pattern.

topstitching fly front

Now it’s time to insert your zipper. In the photos below, I am lining up the left edge of the zipper teeth to the center seam. I shot these pics before I sent the pattern out for testing, and a few people pointed out that they preferred their zipper to be set deeper in the fly so it doesn’t peak out at all. If that’s the case, align the left edge of your zipper tape to the center seam. Depending on the width of the zipper tape, this will set your zipper into the fly 1/2″ – 3/4″. It will not effect the size of the waist, just the location of the zipper. Make sure your zipper is face down.

installing zipper for fly front

Once your zipper is aligned the way you prefer, pin it into place along the right fly extension only. In general, I line up the bottom of the tape with the bottom of the fly extension. You want at least 1/2″ between the bottom of the fly extension and the zipper stop since you will be topstitching here later and you don’t want to hit the stop with your needle.

installing zipper for fly front

Using a zipper foot, sew close to the zipper teeth, ensuring you are stitching only to the right fly extension. You can sew another row of stitching along the right edge of the tape as well, but it’s not mandatory since chances are your zipper tape will wind up being encased by the fly shield later on.

installing zipper for fly front

Flip the zipper and the right fly extension under. You will now have a strip of denim to the left of the front of your zipper. You may have a little more width than what you see here depending on where you aligned your zipper tape.

installing zipper for fly front

Stitch a line about 1/8″ away from the folded edge of this strip using a zipper foot.

installing zipper for fly front

Flip your legs back so that the wrong side is facing you. If you grab the zipper and the right fly extension, you’ll notice that you can now move it to the left. Fold it to the left as much as it will go without pulling the fabric. Pin it into place.

installing zipper for fly front

Sew close to the left edge of the teeth, and sew another row close to the edge of the zipper tape to secure it the left fly extension only.

installing zipper for fly front

Your zipper is now sewn in! Round of applause. Turn your jeans over, and use the fly topstitching guide to trace a line on the front of your pants. Make sure the  bottom of this guide is at least 1/2″ below your zipper stop while still catching the fly extension below – I like to mark the location of the stop with a pin. Trace another line 1/4″ inside the one you just drew.

marking topstitching for fly front

With the front of the jeans facing you, topstitch along those guides, making sure your fly extension is laying flat. Sew slowly around the corners, watching the needle rather than the guide to make sure your line has a nice curve. Stop stitching at the center front seam, and backstitch a few times to secure.

ginger skinny jeans pattern - installing fly front zipper-25

Almost there! Before we add our bar tacks to secure the zipper, we need to prepare the fly shield. Fold it right sides together and sew 5/8″ along the angled edge. Trim to 3/8″, snip the corner and press flat.

ginger skinny jeans pattern - installing fly front zipper-26

If any little corner pieces are peeking out you can snip them too.

ginger skinny jeans pattern - installing fly front zipper-28

Turn your jeans so the wrong side is facing you, and line up the folded edge of the fly shield to the finished edge of the left fly extension. Pin into place.

ginger skinny jeans pattern - installing fly front zipper-29

Depending on where you aligned your zipper tape, you may have to trim off the excess on the right fly extension. If you have a serger, sew the fly shield to the fly extension only, cutting off any excess as you go. If you’re using a regular machine, you can finish this edge with a zigzag or overlock stitch, or wrap it in some bias tape. Again, please ignore my horrible serging below. Damn serger timing!

how to secure serged stitch

If you’re serging, use a large darning needle to weave your thread tail back into your serged stitch so it doesn’t unravel on you later.

how to secure serged stitch

From the front of your jeans, mark where you’d like your bar tacks to go. I generally sew them just above the where the topstitching curves, and just below the zipper stop. If you have any wonky topstitiching on your curve, you can hide it with some bar tacks!

bar tacks at fly front

Practice some bar tacks until you get the tension and width right. You can use regular thread in your bobbin, but you may have to tweak the tension to get a nice even stitch. On my Bernina, I set my stitch length to .5 and my zig zag width to 1.5-2, which gives me a dense, strong bar tack. You basically want the same stitch you use for buttonholes here, so check your machine buttonhole function to get the right settings (thanks to Sallie for that tip!) When stitching, make sure your fly shield is lying flat – the bar tacks will help secure it in place.

fly front with bar tacks

fly front fly shield

Remove your basted stitching along the center front seam using a seam ripper to just above your topstitched lines.

fly front zipper

AND YOU’RE DONE!! I know there were a lot of photos in this post but I’m hoping it helped you figure this step out. It can be a little confusing at first but once you get a handle on it, it becomes second nature.

If you’d like more help sewing professional looking jeans, consider taking our online video class. The Sew Your Dream Jeans Workshop will give you the tools and techniques to design, sew, and wear your very own custom pair of jeans with confidence.

Sew Your Dream Jeans: ultimate online sewing class to teach you to sew jeans


  • thank you so much for all the photos! i was worried the fly front would trip me up but i think i can follow these photos! (i can understand things so much better by seeing than just by reading.) now i just wish i were at home in front of my sewing machine so i could start right now! (rather than being at work…) thanks again for writing these posts

  • Amanda

    This is a great post! So clear and all the photos really make the process simple to follow. I just need to cut my fabric. That’s usually the point at which I have the hardest time getting going. The only way your sewalong (or kit) could be improved is if you could cut the fabric for me;-)

  • I’ve been looking forward to this tutorial because of the rave reviews I’ve seen about your instructions. I think I’m still going to do it another way, but great to have as a reference (I generally prefer separate facing pieces). One thing though, obviously anyone can do what ever they like, but I’ve never seen jeans with a double row of topstitching above the zipper stop on the fly.

    • My favourite RTW jeans have the double top stitching along the CF and I think it’s a nice detail. You can also do a single line, or none at all above the zipper stop but then you have to wait till it’s installed before top stitching.

      • Absolutely, in the immortal words of Grease, the rules are there ain’t no rules!

  • charlotte

    fantastic tutorial, thank you! Just wondering, how does the pocket stay figure into this? Do you just pretend it’s part of the denim (like an underlining)?

    • Exactly! Just treat it like an underlining. The fly front construction should secure the lining so it does it’s intended purpose- keep everything nice and tucked in.

      • charlotte

        thanks so much!

  • Sharon

    Best zipper/fly tute ever. EVER! Thank you so much.

  • Nicole Bertram

    Thanks for the great tutorial! I am working on a purple pair of gingers, and though the instructions are clear, real photos always help.

  • Willknitforbeer

    Thanks for all of the photos. i didn’t “get it” until the last photo! 😉

  • Magdel Du Randt

    I might be a blonde in asking this question, but what happens to the top part of the zip? What if you’re sewing a pair of trousers that does not have a band at the top – do you then reposition the zip so that the top bit doesn’t stick out over the edge?

    • If you’re sewing pants without a band you would need a zipper that is precisely the length of the opening since you have nowhere to hide the extra zipper tape. But you could not do a fly front zipper without a waistband. You need to sew the fly panels into something to secure them.

      • You don’t actually say it here but I’m assuming you just cut off that extra length of zip at this step, is that right?

        • Not yet! Wait until the waistband is one, otherwise you might accidentally remove the zipper pull.

          • Thanks! I decided to jump the gun and cut before the zipper was sewn on… For anyone reading this that’s a bad idea, made it so much harder to sew the zip on… Live and learn !

  • Marlise

    This tutorial is fantastic! Thank you so much!

  • meow

    On the step to top stitch the double rows to the right of the front seam, should the fly extension be caught in the top stitching or moved out of the way?

    • The left fly extension should be caught in the stitching.

      • meow

        great, thanks!

  • Marianne Cullen

    Thank you! Best jeans zipper I’ve ever done!

  • Mimi

    Beautiful work!

  • Josie

    Thank you so much! Best zipper tutorial! I’m such a visual learner, I LOVE the step by step photos.