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Making a Side Seam Read True

Take the muslin apart, and transfer this red line back onto the paper pattern pieces.

In a recent post, there was a question about how to make the side seams on a dress read true. This is another illustration of the net gain/net loss/no-net-change conversation we’ve been having through the articles we published, as well as the last post. The alteration to accomplish this is a no net change across a seam line.

I’m illustrating this using a trouser as my example, but the principle is the same for any garment.  

In the first picture, you see the trouser, with a side seam that isn’t plumb with the floor. This happens when there is more flesh either to the front, or the back, of the midline. What’s happening in the garment, is that one side “borrows” from the other, causing the seam to pull to the front or back.


To reposition the seam so it reads plumb, take a ruler,
and draw where you want the final seam to sit. This is
the red line in the picture.


Take the muslin apart, and transfer this red line back onto the paper pattern pieces. The black line in this illustration represents the correction.

This alteration is a no net change across a seamline. You aren’t going to change the total circumferences in this area, but you will just rearrange where the fabric will go.

The shaded areas on the front, and back pattern pieces are rearranged. You’ll trim off the front to add to the back, and trim off the back to add to the front.


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  1. jsnoble | | #1

    Brilliant and logical. Thanks.

  2. moviegirl | | #2

    "When something on your pattern looks different than what you're used to seeing in books or illustrations, it's because your figure is different than the "standard" pattern, and needs accommodation. "

    It's so nice to hear an expert say that.

  3. cloff | | #3

    I don't understand - why would you not alter this pattern to fit properly before sewing? It looks like the person needs more room in the "bum" and more room over the tummy...

  4. NinaLBoston | | #4

    This past weekend I took an inventory of fall wardrobe because of weight loss. 1 RTW skirt "fit" at the hips, but when I turned sideways, the seam pulled to the back at hip level, just like this illustration!
    Now, I know that I really can't fix this item; the seam allowances are only about 1/4 in. But it's great to know how to make an adjustment on my pattern.

  5. erobi | | #5

    Three little screens, so much information. Thank you, Kenneth!

  6. User avater
    grandmapatty | | #6

    Really pointed out the obvious,
    which I hadn't seen! Thank you!

  7. KharminJ | | #7

    @cloff - Precisely: "needs more room in both the tummy and the bum".
    This article is about "How to get that". The *principle* behind making the changes, whether you're currently working with a "pattern", a "muslin" or a finished garment that doesn't hang right.
    You're right, the earlier in the process this problem is addressed, the easier it is to deal with... but it's likely not noticeable until some sewing is done.

  8. KharminJ | | #8

    Thank you, Kenneth! "Brilliant and logical."

  9. simplypat | | #9

    Kenneth King can play with my pants anytime! He works miracles on fit.

  10. User avater
    CFields | | #10

    I see the logic of this simple adjustment but won't you now have to make a curved, shaped seam and ease the pieces together? Won't be harder to keep the seam flat?

  11. User avater
    LuvThreadsMagazine | | #11

    Senor King, you take the quirky and disconcerting, and make it sensible and stress-free.

    Mucho gracias for your patterning geometry tutorials.

  12. User avater
    sewlore | | #12

    Thank you. The correction is so mathematical. On the emotional side, I love the equation in which if it looks right on me it is correct.

  13. User avater
    sewlore | | #13

    Thank you. The correction is so mathematical. On the emotional side, I love the equation in which if it looks right on me it is correct.

  14. User avater
    ustabahippie | | #14

    Great advice. I can't wait to try on my last pair of self-made pants to check out the side seam fit. I hope they "read true" but glad to know what to do next time if not. Thanks Mr. King!

  15. User avater
    BarbaraHewitt | | #15

    Thank you for putting diagrams and words to the way I would make a straight side seam on my skirts.

  16. User avater
    Marie_S_G | | #16

    This looks simple. If I look to real world problems, this is a case where there is a too big but and abdomen in a pair of slacks designed for a different body shape. Usually there is a lack of fabric to contain the actual body resulting is strains, wrinkles and other deformations in the crutch line, not only a S-curve in the side seam. Will this movement of the same fabric really solve the problem of lack of fabric? You will hardly see this side seam if there is ease enough to provide the fabric needed by the larger body. Will not this just move the problem "lack of fabric" around to other places?

  17. User avater
    triangles | | #17

    Very simple explanation. We seem to make things harder than they actually are. We over fit and over think our muslin issues. Its always about the basics, isn't it?

  18. jrssews | | #18

    Thanks Kenneth! Once again you have clearly explained something that has stumped me in the past.


  19. User avater
    kennethdking | | #19


    To answer Marie SG: Even if you have enough wearing ease in the garment, be it a skirt, trouser or whatever, this is a case of how the flesh is distributed on either side of the midline. Since fabric is essentially a grid, there's an imaginary midline through the "cylinder" that the body is. Sometimes the flesh is more to the front of this midline, sometimes it's to the back.

    Imagine two stacks of coins, one perfectly stacked into a cylinder, and one that is stacked onto a wobbly stack. Both would require a tube (skirt) of the same circumference to fit, but in the second case, the side seams would be wobbly.

    This may seem to be an esoteric explanation, but it's how it was explained to me by a man at a party who studies physics.

    To answer CFields: Yes, you will have side seams that are curved to an extent. You won't have to ease anything, as both seams are the same length. You will, however, need to stretch the seam allowances on the inside curves (such as you would for a princess line) so you don't end up easing one onto another. It may be a little more effort in construction, but it's worth the effort to have the side seams hang straight--when they are plumb with the floor, it flatters the figure considerably.

    To KharminJ: Exactly right! Ideally you want to correct things earlier on, but my experience is that somethings just are better dealt with in the muslin, instead of essentially "guessing" at where a side seam would fall. It's easier to just take out the ruler and draw the seam where it needs to be on the muslin.

  20. User avater
    kennethdking | | #20

    Again, to MarieSG: Also, look at my explanation using the stacks of coins. It really solves the problem of lack of fabric in one area and too much in another. This is a fix that I've used for years, and I know it works.

    It all has to do with the concept of "no net change" across a seam.

  21. User avater
    kennethdking | | #21

    And to Moviegirl: Glad I could confirm what you already know!

    This is a concept I swim upstream with teaching at F.I.T. There's the "industry" way of looking at a pattern, that involves a fantasy world of dress forms and impossibly slim models, so they don't have this question arise.

    But when one is making custom clothing, the imperative is to fit and flatter any figure. And the solutions will sometimes look unorthodox to my colleagues in ready to wear. But I tell my students, that however the pattern looks, as long as it reads correctly ON THE FIGURE THEY'RE DRESSING, that's the gold standard, and the correct pattern for that figure.

  22. flatCAD | | #22

    I really would like to see an actual garment with opposing curvatures at the side seam that look straight on a body. "No net change" may work on some areas of garments if done correctly, however in this case, a straight line would make a more slendering seam". I bet a pair of pants made using this pattern will show signs of curvature as in the original figure when different fabrics with different stretch properties are used.I don't think this is a practical way to fix things. If starting from fabric, fix the pattern before cutting. If not, the seam allowance of already sewn garments would probably be insufficient to allow for this alteration.

  23. User avater
    kennethdking | | #23

    To answer Flatcad: You write:

    "If starting from fabric, fix the pattern before cutting. If not, the seam allowance of already sewn garments would probably be insufficient to allow for this alteration."

    Indeed, one strives to fix this in the draft. But if you left wide seam allowances and fixed this in alteration, then took the garment apart and compared it to the pattern, it would look like the pattern fix we're discussing here. Same thing, moving fabric from one side of the seam to the other, to straighten the seam.

    Different ways of getting there, both work.

  24. User avater
    Marie_S_G | | #24

    If I were so basic that I was working with a muslin why not start with adding to the front and maybe adding a dart also to cover the curve of a large abdomen. The muslin you are modifying must have started with a "standard" figure. You would never draft this first muslin from the metrics of the figure you are fixing?
    By taking fabric from the back to the front will the back then cover what it need to? This fix will not move the flesh. The larger bottom need rather to get some more fabric by adding to the crotch line maybe.
    Curves in the sideline to make the seam straight must be a solution overlooked by pattern designers making muslins, as they seem to grasp for other solutions.

  25. User avater
    kennethdking | | #25

    To answer Marie SG: There are different ways to get to a solution. When I draft from scratch, even though the system I use is quite accurate, I find I need to do this. If you can draft a pattern that accounts for this accurately, then that's another way to get there.

    I'm assuming here, that most of the readers here are starting with a commercial pattern, not drafting from scratch. So this particular fix is useful to them.

    There are different ways to get to a solution, depending on the experience and amount of available time the individual has to work on a project. Some have the time to learn how to draft and take the time to do that, others want to start with a commercial pattern and work from there.

    In other words, there's more than one way to get to a solution, and, as long as you arrive at a solution that works, it doesn't matter how you get there.

    Perhaps you might like to do a post illustrating your method, so we all can learn? I'm always up for learning something new! That's the beauty of this particular discipline--there's always something new to learn!

  26. User avater
    CFields | | #26

    I can certainly see how and why this works. I guess I just have more experience with the "slash and spread" (or fold) technique when altering commercial patterns. The results are similar. As you say, there's more than one way to dress a cat.

  27. User avater
    kennethdking | | #27

    Indeed there is, CFields!

    When I was trying to get my head around fitting, I wanted to find the underlying principle--for me it's the net gain/net loss/no net change concept. I find that this underlying principle is what undergirds the different methods of altering patterns. It gives me a framework within which to reason out a solution.

    The slash and spread/fold method is one of the ways, and others are outlined in Threads as well as other publications. As long as the finished result fits, however you get there, gets you there. And that's what I love about this discipline. The different ways to get there, and learning new ones.

  28. Terrie_MK | | #28

    I agree with Marie S G, KharminJ, cloff, moviegirl comments. What you are recommending is a short cut, after the fact, fix to pants that don't match the body they cover. Your solutions treats the symptom not the cause of the problem. If this is a muslin, and the fashion fabric has not been cut yet, take the time to get the fabric correctly fitted in the center front and back of the garment before cutting fabric. I'm sure your method works when the wavy side seam is only a slight wave (can be accommodated with available seam allowance). Pattern pieces made using proper design rules for a nonstandard body shape will have a different shape from the standard pattern pieces out of the package. If the patterns pieces are corrected for the shape you are trying to cover, when assembled, the fabric should hang "true". The straight grain should hang straight and the cross grain should be horizontal for the example shown in this article.
    How well you can get by with this technique also depends on the weight and drape of the fabric you are working with.

  29. User avater
    ginnylynn | | #29

    I'm late to this party I guess - so much has been said and debated already!

    I only wish that I, and probably hundreds or thousands of others like me out here on the Threads site, were part of the elite clique of those who appear to be classically trained in tailoring and haute couture methods and techniques so I could contribute in some meaningful way to this discussion, but I - and they - are not.

    Maybe I'm misunderstanding much of the material in the books and articles I read but it seems to me that creation of muslins is not a dirty little secret, but a valued and recommended technique in common use - particularly when the fashion fabric is in short supply, is very expensive, or should not be over handled (vintage fabrics for example).

    I'm neither ashamed of my skill level nor afraid to admit that I find the use of muslins to be both a time saver and a convenient playground for my ideas around how to resolve a fitting problem.

    To me, Kenneth D. King is a revolutionary in the design field, using logic and his own senses to come up with unusual and unconventional ways to produce beautiful, and beautifully fitted, garments without a need to worry about doing it the way it "should" be done. He reminds me in many ways of Alexander McQueen. Perhaps those very qualities, though, are the source of so much seeming anxiety over his methodologies. It makes me think about how "real" musicians often look down upon those who are naturally gifted and play by ear without any formal training.

    Mr. King, I salute you and your natural talents, and I look forward to many more pleasurable and productive hours spent with your articles, books, and courses in my efforts to marry my own natural creativity with my growing skill in sewing and garment construction. Thank you for so generously sharing your talents.

  30. User avater
    kennethdking | | #30

    To GinnyLynn: I blush! Thank you for such kind words--comparing me to Alexander McQueen even! I don't think I'm in his league, but I do passionately love what I do, and think about it constantly.

    You are right about making muslins, though--in the book on John Galliano (sadly disgraced as he should be for saying such things), the author tells that, in his atelier, there at least three, and sometimes up to six muslins made before fabric is cut. This bit of information made me feel better about my abilities--I thought I was just stupid that I couldn't do it all on the first shot.

    I think we have a couple of "take-aways" here, that we all might agree upon: That there are many ways to achieve a particular end, and that making muslins is a valuable process.

  31. juliebell3 | | #31

    Mr. King, I'm becoming a believer that there's a teacher for all of us, because we each learn a little differently. For me, you are the first person to make fitting really make sense for me. Since I started to read your contributions to Threads and more recently watching Threads videos on fitting, I have to say you're a great teacher and communicator of the fitting, sewing and design process. I was also relieved to hear you talk about making more than one or two muslins. Now I realize that if the pros do it, then it makes sense that I should too. Thank you for reaching out to us home sewers.

  32. Sew4Life | | #32

    Love you Kenneth, but to me, the problem shown in these pictures is not that the side seam is not straight, but that the pants are too tight. The front is curving under the abdomen, which to my eye is not flattering, so no matter whether the side seam appears straight with these changes, the fit is not good and the distortion of the side seam is a symptom of the poor fit.

  33. user-7225691 | | #33

    I teach flat pattern and look for interesting techniques to share with my students. In this instance I agree with readers saying this method is not a good solution. We are all guessing based on our experiences. Only an actual pair of pants fixed using this method would diminish the doubts. Seeing is believing (mostly!)

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