13 May 2016 • • by Heather Lou

How to Install a Button Fly

How to Sew a Button Fly

One of my favourite features of the Morgan Boyfriend Jeans pattern is the button fly. I love a good button fly (always the best thing about vintage jeans!) but I was really confounded by their construction until I took an old pair apart to figure out how they worked. Turns out, that it's not hard to sew at all! In fact, it's probably easier to install than a fly front zipper since there are fewer steps and less zipper flipping, always the part that confuses my students. In this tutorial, I will show you how to sew a button fly, it couldn't be easier!

If you want that classic vintage look (which looks especially cool when it distresses naturally over time and fades on the fly of the jean), the button fly is the way to go. It first showed up as the original closure on the very first pair of 501s in the 1870s; zippers weren't invented until a good 20 years later. Traditionally the inner fly buttons are a little smaller than the typical jeans button; they are hard to source but luckily we now carry button fly kits in the shop in three finishes, so you can install the typical 17mm button for the main closure and use the 15mm buttons inside your placket.

You will need:

  • The Morgan Jeans Pattern
  • Non-stretch denim
  • Jeans buttons (size 0-14 x 4, size 16-18 x 5, size 20 x 6)
  • Denim rivets (optional)
  • Topstitching & regular thread
  • 1/4 yd fusible interfacing
  • Marking tool
  • Denim needles
  • Button chisel
  • Fray check


Once your front pockets have been installed, place your legs right sides together and align along the fly extension and front crotch seam. Baste a line of stitching from your center front notch to the circle marking (I find it helps to draw this line with chalk so you sew in a straight line). From the circle mark down, switch to a short stitch length, back stitching right when you start stitching again. Trim and finish the crotch seam and cut a notch from beneath fly extension to circle marking.


Press the fly extension open and the finished crotch seam to the left. Serge the left fly extension to finish it.

How to sew a button fly-10

On the right side of the jeans, stitch a single line of topstitching 1/8" away from the center front seam on the left leg. Once that line of top stitching is done, use your template to mark your fly topstitching with a piece of chalk or my favourite tool, a Clover Chaco Liner. The topstitching should catch the fly extension beneath.

How to sew a button fly-15

Now you'll want to prep your button fly shield and placket. Press the shield right sides together and sew along the bottom diagonal edge. Trim the seam down to 1/4" and snip off the inner corner so it will turn crisply on itself.

How to sew a button fly-7


Press your fly placket wrong sides together and finish the raw edge with a serger or zigzag stitch (if you're serging, use a hand sewing needle to thread the loose end of your thread trail back into your stitching along the curved side so it doesn't unravel). Sew your buttonholes as indicated on the pattern piece - you want them to start about 1/4" away from the folded edge of the placket. When finished, both pieces should look like this:

How to sew a button fly-8

Strengthen your buttonholes with some Fray Check. You can open your buttonholes with a sharp seam ripper, but I prefer to use a buttonhole cutter which ensures an accurate cut with no severed threads.

How to sew a button fly-11


On the wrong side of the jeans, line up the placket with the left fly extension. it should line up with the top of the jeans and sit about 1/8" away from the center front seam - you want it inset just slightly so it's not peaking out when your jeans are closed.

How to sew a button fly-12

Pin into place along the top of the pants and through the front of the jeans. You'll be topstitching through the left leg and the placket so I find it easiest to keep your pin where you can see it.

Topstitching a button fly // Closet Core Patterns

With the placket secured into place, topstitch the first line of fly stitching starting at the top of the jeans, slowly following the chalk guide you added earlier. Backstitch as you approach the center front seam. Make sure you are catching the placket evenly in your stitching.

Topstitching a button fly // Closet Core Patterns

Repeat another line of topstitching 1/4" inside the first one. Backstitch again as you approach center front.

Topstitching a button fly // Closet Core Patterns


Flip your jeans to the wrong side again. It's time to install the fly shield, but first we need to remove some excess width from the right fly extension. Trim off 1" from the extension.

How to install and sew a button fly // Closet Core Patterns

Line up the raw edge of the fly shield with the right fly extension. Sew together at 3/8" seam allowance and then finish the seam (you can serge it, zig zag it, or finish with bias tape).

How to install and sew a button fly // Closet Core Patterns

How to install and sew a button fly // Closet Core Patterns

From the right side of the jeans, remove the basting stitches securing the center front together and press the shield flat. Secure the fly shield in place by topstitching as far down as you can go along the right leg, about 1/8" away from the seam.

How to sew a button fly - topstitching fly

The joint between left and right leg is a little wiggly right now. To really secure everything together, pin the fly into place again through all layers. Starting at the bottom of the crotch seam, sew a second line of topstitching along center front, 1/4" away from the first line. Stop stitching about 1/2" after the curved fly topstitching double line. You can angle this out a little as you cross that curved line. If I'm going to do that, I mark it with chalk first so I have a guide to follow as  I sew.

How to install and sew a button fly // Closet Core Patterns

Once you've sewn past your curved line a ways, leave your needle down, turn your work and die the stitching into the center front seam, making sure to backstitch a few times.

How to install and sew a button fly // Closet Core Patterns

For extra support, add a bar tack at the top of this small horizontal line of stitching and along the curved portion of your fly stitching (my favourite setting for a bar tack is 2 wide and .25 long). This really locks the placket, shield and pants together nicely.

How to install and sew a button fly // Closet Core Patterns


Once your jeans  are assembled and you've sewn your waistband buttonhole, you can mark the locations of all your buttons. Close the jeans and use a pencil to mark the button location through the buttonholes.

Installing jean buttons // Closet Core Patterns

The critical thing is to line up your buttons on the far side of the buttonholes (closest to center front). This ensures your jeans will actually fit correctly and all the buttons will be sitting in the right position. For the inner fly buttons, this will mean installing them around 1/4" away from the seam.Installing jean buttons // Closet Core Patterns

Use an awl or a hammer and nail to make holes for your button backs. Push the button backs through.

Installing jean buttons // Closet Core Patterns

Once all your backs are in place you can install the buttons. You can use a piece of wood to hammer these in place (but please note that rivets need to be installed on a steel surface). I now use my mini anvil from Tandy Leather to install all jeans hardware so that's what I'm using here. Put your button face down and then center the button post in the buttonhole. Try to get everything lined up so that the post is going in straight. Give the bottom of the post a few good wacks with your hammer, ensure its going in straight, and then finish off with a few more taps. If you want to use a hand press, we have a tutorial here on how to use that.

How to install and sew a button fly // Closet Core Patterns

Time to enjoy that vintage button fly goodness!

How to install and sew a button fly // Closet Core Patterns

If you'd like to do an exposed button fly like Morgan did, you would simply omit the button fly placket and sew your buttonholes directly to your front fly.

Hope this helped you learn how to sew a button fly on your Morgan Jeans, although you can certainly use this method on any pants pattern that needs a classic touch!

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How To Sew A Button Fly


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