here is the fly-front zipper tutorial i promised y’all! it’s not perfect by any means – i’m still learning zippers myself! but this is a pretty easy, tried-and-true method that delivers great results.
you want to start with the front of your shorts (or pants!), sewn together up to the point where the bottom of the zipper will reside. we will be working flat – no back or side seams yet. this makes the insertion much easier and quicker.
here i have prepped the shorts for the insertion – the front crotch seam is sewn as indicated by the pattern markings, back-stitched by where the bottom zipper stop will end up. from the back-stitch, you want to increase stitch length to a basting stitch & continue basting all the way up the center front to the top of the pieces. i have also interfaced my zipper facings – it really helps keep everything from getting puckered and/or wonky. cut the interfacing so the non-stretch is going vertical. also, if you want to finish the edges of your facing, now is the time to do so. i have serged mine.
clip the seam allowance at the back-stitching (where the basting begins) – all the way to the stitching, but not through it.
open out your facings & press them flat.
and flat. yeeeah, there are threads & bits of interfacing everywhere. i never claimed to be a tidy sewer!
ok, here’s the fun part! flip your zipper over so the back side is facing you. place it on the facings so that the edge of the zipper tape is lined up with the middle of the facings, i.e., the basted seam. pin the zipper to the facing on the opposite side, making sure you only pin the facing. don’t pin the shorts, we are just going to sew the facing right now!
stitch the zipper to the facing only, on the side that we pinned. for seam allowance, i like to go with whatever the width of my presser foot is.
this is kind of a “doh!” tip but it OPENED WHOLE NEW WORLDS for me when i discovered it – if you have trouble sewing past the zipper pull (and, like me, aren’t savvy enough to buy a zipper that is too long, whoops), try this trick: when you get about an inch or so from the pull, lower the needle into the fabric, lift the presser foot, and pull the zipper tab down to the bottom.
no pull! now finish sewing!
after you have sewn the zipper down to the facing (remember? just the facing. gaaah this part always trips me up lol), flip it back so the right side of the zipper is facing out and the edge is neatly folded under. sew down with a 1/8″ seam.
sewn seam.
ok, the next part is kind of hard to explain and thus is why i *always* mess up my fly-fronts:
zip the zipper up and lay it down on the other side of the facing, right side of the facing meeting right side of the zipper. don’t try to match up the edges – they aren’t supposed to match up. just let the zipper lay where it feels like hanging out & pin it down to ONLY the facings (have i stressed this enough? are y’all getting agitated with me yet? 🙂 )
here is the opposite side of the above picture, for more clarity.
once you have everything pinned, take it to the machine & sew it down – once again, i used whatever seam allowance was the width of my zipper foot. go slowly & watch out for that tab!
NOW it’s time to sew the shorts (yay!). your pattern should have markings for where you stitch, which you should have transferred to your pattern pieces. you can also just wing it & draw them on like i did – i marked about 1 1/4″ away from the center seam, and tapered the bottom curve to end below the zipper stop. if you need to, put a pin where the zipper stop is so you don’t sew over it.
sew this line through all layers – the facing (well, one side of the facing – the other side should stay flat like god meant it to) and the shell fabric. back-stitch at the top & bottom. mine ended up being a little wonky at the top because of the zipper pull 😦
now take your seam ripper & rip out those basting stitches!
and: success!
and, of course, the obligatory interior shot.
i hope this helps someone! fly-front zippers can be intimidating, but they are actually pretty easy once you figure out the steps to insert one 🙂
LLADYBIRD 
Thank you… this is actually much more clear than other tutes I’ve seen for fly fronts. I may actually be able to brave one now (I’ve only got three little boy pants waiting for… something. I haven’t moved past this point due to fear of fly front zipper vs. unwillingness to play with my machine and buttonholes inertia). In other words, thanks. Again.
This is the best tutorial by far! thanks so much, helped me heaps.. i almost gave up on these shorts until i found this amazing site, thank you so much !!
Thanks so much for this tutorial! Thanks to you, I just sewed my first fly front zipper perfectly!