Flat fell seam


Before we get into the actual cutting and assembly of your Ginger Jeans, it is worthwhile to go over the variety of seam finishes you can use, since sturdy seams are the key to making jeans that will last for years.

A note about machines: you can make this pattern using one regular machine. If you’d like to avoid changing your topstitching thread in between steps, having a second machine set-up can be helpful for sewing regular seams exclusively. However, because you don’t need to put topstitching thread in your bobbin, I was never particularly annoyed by changing to regular thread on top. Having a serger makes finishing seams a breeze, but is not required, especially if you want to use flat fell seams.


The original jeans seam finish: sturdy enough to withstand the rigors of gold mining, and pretty enough to be worth the time for your own jeans. These seams are similar to french seams in that the raw edge is completely encased but the process is a little different.

To start, sew your 5/8″ seam like you would normally with right sides together. Then trim one side of the seam to 1/4″ (trim the side that you intend to press towards). You can use scissors to trim, or a rotary cutter if the seam is straight.

Flat Fell seamFlat Fell seam

Press the seam down with the long edge on top.

flat fells eam

Fold this long seam under, making sure you are encasing the shorter seamed you just trimmed. Press flat – if you have a clapper this is the perfect time to use it.

Flat fell seam

pressing flat fell seam

Traditionally you would sew the seam closed from the wrong side of the fabric, but the bobbin side of topstitching is generally not very pretty. We will be sewing from the right side, so it’s important to carefully pin the seam closed since you won’t be able to see it when you’re sewing.

Flat fell seam

Start topstitching 1/8″ from the seam line. Sew another line of topstitching 1/4″ away, making sure you are catching the folded seam below.

Denim topstitching

When you are done it should look something like this on the inside:

Flat Fell seam

Clean, rugged, and guaranteed to last. Flat fell seams are definitely more work, but I think the final effect is totally worth it. Keep in mind that these are quite thick seams, something to think about if your machine gets angsty going over multiple layers of denim. For this reason, I would not flat fell your front crotch seam. Serge it or finish it using the technique below. Every RTW pair I’ve looked at serges the front crotch, I’m guessing to reduce bulk at the crotch inseam intersection.


If you have a serger, you can get a clean finish inside by trimming and overlocking your seams before topstitching. Sew your seam on your regular machine and finish it on the serger – trim off about 1/4″. You want to make sure your seam is still wide enough to catch the two lines of topstitching. Quick serger tip: you should have some guidelines on your machine that indicate seam allowances just like a regular machine – you can see in the example below that I am aligning mine with the 3/8″ mark, just next to the cutting knife.

serging jean seam

Press the seam flat and sew two lines of topstitching 1/4″ apart. It will look like this on the inside.

serged jeans seam


If you don’t have a serger and don’t want to do flat fell seams, you can still get a pretty clean finish by trimming your seam allowances to 3/8″ and zig zagging the seam using the widest zig zag possible. Even better if your machine has an “overlocking stitch”. On the example below, I used an overlocking stitch next to a zig zag stitch to show the difference.

Finihsed jeans seam


This may be one of the trickiest things about making jeans. Since your topstitching thread is most likely in a contrasting colour, it’s important to sew slowly and carefully, especially around curved edges like the pockets. There are a few feet that may help you get clean, even lines, but I almost always use my standard foot. Here is how I get even topstitching using a normal foot.

For the first pass, I align the centre guide on my foot to the seam line, and move my needle over about 1/8″ (this is only possible if your machine has more than three needle settings).

topstitching jeans

For the second pass, I align the left inside edge of my foot to the first line of topstitching, keeping my needle in the same position as the step before. This gives me 1/4″ between lines of topstitching.

topstitching jeans

Even if your needle only has three positions (left, center, right) try experimenting with the feet you have to see if you can find an easy way to align your topstitching. Once you have this part figured out it goes much more smoothly! Write down your settings if it will help you remember later.

If you have an edge-stitch foot, you can use the guide in the centre to help create nice, straight topstitching lines. Personally, I never use this method even though I have the foot because I always end up with tension issues. However, my machine can be a little moody with topstitching thread, so I encourage you to give it a try.

edge foot for topstitching jeans

If you’re having issues sewing around curves, make your stitch length a little shorter; 2.5 – 3mm works well for me. Draw guides with a chalk pen if it will help you stay on course, and look at the needle rather than the seam guide so keep that line as smooth as possible.

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  • Heather Petersen

    What about bias binding? Would that be too bulky for close fitting jeans? I’ve done it with some chinos for my seven year old. Just a thought, I totally dig how it looks.

    • Hmmmm…. I think this would make your seams too bulky but you could certainly try on a scrap to see… The only place I’ve ever seen bias tape used in jeans is along the fly shield and pocket edges.

      • Heather Petersen

        I’ll probably end up serging anyway. I’ve gained a bit of weight and am in desperate need of clothes to wear this winter.

        • I serged almost all of my jeans until my serger gave up the ghost a few weeks ago…

    • AuntyMaimu

      It can be done, but then the material you are using for binding has to be very thin and yet durable. Reval Denim Guild uses bias bound seams on all of their jeans I think.

  • missceliespants

    I’d also like to recommend using a 1/4 inch foot when doing the second row. I used it recently in top stitching and it gave the most professional results I’ve had.

    Has anyone ever used top stitching thread in their coverstitch machine? I’m tempted to try it for finishing jeans myself.

    • I desperately need a coverstitch machine…..

  • Interesting ! Last time, I did flat seams ont the right side (for the Jedediah Pants), it was tricky… what a good idea to make them on the wrong side 🙂
    I’m a bit afraid with the topstitching…

    • Pins! And experimenting with your feet to come up with a consistent topstitching strategy should help. If you use a clapper (or other piece of hardwood) when pressing your seams, they should stay fairly flat, unless you are working with a really thick denim.

  • LinB

    Flat-felling is far easier done on the outside of the jeans, as in rtw. It is even easier if you offset your seams (wrong sides together) by 1/4 inch. Sew on the 5/8″ mark, then fold the long lower layer over the short upper layer, lay it flat and stitch. Ta dah! The entire seam finishes at 5/8″, you don’t have to trim anything, and all the stitching is on the outside of the jeans. You don’t have to do any more than finger press for natural fibers.

    I used to work for Wrangler jeans, eight hundred years ago, when many of the jeans seams in our product were flat-felled. Granted, our sewers used a flat-fell machine, but the principle of offset seam allowances is the same.
    RTW methods are designed to be efficient as cost-cutting measures. I take advantage of some rtw methods myself, to save time and pricked fingers and ugly sessions of cursing and throwing fabric across the room. Some “slow sew” methods are well worth the effort, and I don’t mind doing them — but flat-felling is a utilitarian method of finishing a seam that need not take as many steps as you imagine it will take.

    • Hi Lin. Thank you for this comment! I am fascinated by your Wrangler experience 😉

      I studied a few pairs of RTW and it seemed to me that they were sewn from the inside, since the folded edge of the fabric seemed more “Flush” i guess the word is, from the outside than the inside, due to that first sewn seam. But perhaps this is the result of using an flat fell machine? I figured if it was felled from the outside that seam edge would be a little more pronounced….

      I’m trying to wrap my mind around offseting the seam. I mocked up a sample and it appears to me that the offset seam would still be short by 3/8″. By wrapping the longer 5/8″ seam around the 1/4″, where does the other 3/8″ come from? Unless you mean offset both seams, so one is 1/4″ and the other is 1″, which would throw off the balance between front and back no?

      • Amy

        I know, I remember the first time I saw this method on an Islander video I was totally mystified at how the offsetting works out, but it does… So I tested it with paper. Try it with two pieces of paper with a 5/8” seamline marked in. Measure from the edge of the paper pieces to the seamline and add that together so you know what the finished width should be. I offset by a little over 1/4”, then fold again 3/8”. When you measure from edge of paper to edge of paper you’ll see it finishes at the exact width, and the seamlines lay on top of each other. You have to think about the seamline as being centered on the folded area, not the fold itself. From the edge of the fold, one side loses 1/4” and the other gains 1/4” but between the offsetting and bend allowance it really does work out perfectly. Paper is thinner than fabric so it may end up 1/8” longer but this is taken up when working with actual fabric. Both methods are just great, though, imo—it just depends on my mood!

      • Grace

        I agree with your assessment of the math on this. If you offset and then sew on the 5/8″ seam line for one layer, than the seam will always be off by the amount of the offset. I suspect that an original seam allowance width is closer to 1/2″ would make that 5/8″ first seam on the outside of the seam line on the longer side. I’m still working this out.

    • Grace

      This is exactly what I’m trying to wrap my brain around and I don’t quite get it. When you sew “on the 5/8″ mark” is that the top shorter layer, or the lower longer layer?

  • Carla Lissa

    Correct me if I am wrong, but flat fell seams seems to be more bulky than just serging.

    • They are definitely more bulky! You’re have three layers at the seam rather than two.

  • Amy

    great tutorial, Heather! I love topstitching ;).

  • Deepika

    For topstitching on Jeans, I’ve found the triple straight stitch with blue thread (to match your jeans) in the bobbin and contrasting thread in the needle gives awesome results. No need to use thicker thread which sometimes can create problems in some machines. I need to post a photo of a recent hem I made on RTW jeans.

  • Joanne Roberts

    If I use top stitching thread, which I have, Do I need it on top and in the bobbin? will that stop tension issues of a stronger thread pulling against a weaker one? I would love to know and I am sure others would too. I am cutting this afternoon. YAY! Jo x

    • You don’t need it in the bobbin. You may have to play with the tension settings to get the stitch balance right.

  • julie d.

    Couldn’t you just use a twin needle to get even top stitching? I have to say, the fear of all that top stitching is probably the single biggest reason why making jeans scares the shiz out of me.

    • CONQUER THE FEAR JULIE!! It takes a little patience but it’s totally doable (and it gets much easier with each pair!). You can certainly use a double needle if you’re a little nervous. I’ve just never used one so I didn’t think to include it here….

      • And you can also do your first pair in a matching topstitching thread if you want to hide any flaws.

  • I created a video to show one technique a home sewing can use when sewing a true flat felled seams: https://youtu.be/UQe5gTasl34

    Hopefully, it will be of some help to some of you in your jeans sewing adventures.

    • James Bridges

      Hey Kevin! That glue does not leave any residue on the needle? I was thinking about using spray adhesive, but read that the fumes are bad. Your idea sounds like a good alternative.

      • kevinsews

        If I allow it to dry it never does. Even if it did it will whip off with a damp cloth since it is water based and very safe.

  • Charlotte

    Hi heather,

    I’ve decided to use black denim and so use black thread to keep it uniform. Question regarding the top stitching thread: is it necessary to use topstitching thread for strength or is it merely decorative? I’m just wondering whether I’ll need black topstitching thread or whether normal thread is fine 🙂 would love advice from the pro! Thanks!

    • Hi love. You can totally use regular thread. Not sure if it’s as durable in the long long run (especially around the crotch) but I used it on some of the seams in my black jeans and it’s held up well.

      • Charlotte

        Thanks so much Heather! I’ll give it a go 🙂

  • James Bridges

    Just finished my first seam, Levi style. I skipped the holding stitch and just pinned. Thank you so much for this how to. Awesome!!! This is the beginning of a mens denim jacket for myself. https://uploads.disquscdn.com/images/aa00a547f378cc2de5dd4d58985293ad34556486e30e05091e2c7890560135dd.jpg