The Savvy Sage of Sewing Stimulation

The Sway Back Alteration

This looks like a confusing alteration, but it’s not – I promise.

Let’s walk through the problem and then the solution becomes very clear.

First a swayback problem is most manifested by a set of wrinkles around the waist area in back only.


Something like this.  The normal thought is to take up the waist – a little dart type thingie – like this:


This looks totally logical and really fairly straightforward.

But this alteration actually creates way more work for this wrinkle problem and it doesn’t really solve the problem.

So what is the problem?

What is actually going on here is easy to see, if you pull down the skirt, top, jacket over the hip area till the waist is smooth, you can clearly see or feel that the garment is too tight right below the waist.  When this happens the garment will want to seek an area that it fits or that is smaller, and the waist area is smaller than the hip area.


So here’s a different way of thinking of this, as if the area just below the sway back.  Think about it this way, your back curves in more at your waist than normal, and that causes the hip area to be much larger than the size of the waist – proportionally speaking. So you fit the bodice, waist, and then poof, everything goes wrong just below the waist (although the wrinkles appear at the waist).

NOTE:  For today’s great waist profile, I like to start this alteration a bit above the waist.  This will make the actually thinnest part of the garment silhouette just above the waist.  If you’ve been on this site a lot, you’ll notice I do this a lot.  I do it mostly because it makes a very pleasing silhouette line from the waist to the hip; it’s a sure-fire way to avoid a muffin-top silhouette; and it avoids this sway back wrinkle.  So when you make this alteration, start releasing the seam a bit above the waist – about ½” to 1″ above the waist (depending upon how tall you are).

So because that hip is larger (proportionally speaking), you have to release those seams.  Here’s the kicker, often this is so easy. In addition, all this requires is usually a tiny amount in the seam to lay flatly along the waist and not ride up from the hip to the waist.

And there’s another benefit:  you won’t have the hem level problem that you will definitely have it you make a tuck in the waist.  All in all, this is much simpler, it can be done on RTW and it doesn’t require a hem re-leveling.    Here’s a little video – if a picture is 1,000 words, then a video must be 1,000 pictures or 1,000,000 words!!!!




  1. Thank you “sew” much! I definitely will have to try this! Also , can you show us how to do a FBA on a bodice of a pattern? Thank you again for this article!

    • Well, this is another case of me writing a post and forgetting to publish it….but it’s now up. This is probably the most important fitting dart you can learn, especially in today’s style of the raised waist and the bust and torso area must be fitting to look correctly. This means you buy your pattern according to your shoulder measurement (not bust), because the shoulder is the hardest to alter, but the bust is a piece of cake – with this Bust Dart Alteration technique in your cadre of skills! Practice it and play with a piece of muslin…..go out and buy the pattern that matches your shoulder and make the bust dart alteration. Remember you can measure across the bust after you make it and if you need to add another bust dart, do it. I’ve seen some designers do 3 or more side bust darts which looks really good and shapes beautifully. Try it on and you can refine it in your muslin.

      the link to the bust dart alteration post.

  2. Very interesting. I’ll have to try this. Thanks!!

  3. This is very helpful. Thank you!

    • Try it – it’s a lot simpler and it really works, plus you don’t have to completely redesign the pattern!

  4. Fantastic! It’s like magic! ?

  5. Beal, it is like magic – a little spooky how well it works, but once you reason through the reason for the wrinkles around the waist, it makes perfect sense!

  6. This does make perfect sense for a woven top with a back seam and darts. But, what about on a knit pattern? Especially one that doesn’t have a back seam?

    • Sometimes you are limited here. You’re dealing with two things: 1.) Pitch of the hip/below waist area and 2.) girth of the upper hip area. What is actually happening – considering both areas you’re dealing with – is that you are taking away fabric in front and adding it in back. If you don’t have darts or back seam in your garment, there’s nothing to let out. RTW doesn’t factor in sway back alterations in their garments.

      Here’s how this looks:

      So what’s going on here is at the left is straight (no tilt pelvis), and middle is the sway back pelvis tilt….the pink is where the fabric is taken away and the green is where it’s added.

      But if you’re working with a pattern (and you would need to make this up in muslin first), make the front up as is (you will pinch out what you don’t need later), and add a back seam and add the extra in the back seam.

      So here’s how to do this:
      Figure A is the regular back piece cut on the fold.
      Figure B is adding a seam allowance to center back fold, and
      Figure C is spreading out the below hip/fanny area at the center back seam. Notice I make the waistline a little higher than your real waistline and this helps to modify this line so that there’s not that awful muffin top look.

      To see this on the silhouette side:

      The red line is the muffin top where the garment fits exactly on the waist, and the green line is where the waist is raised a little (I exaggerated here in this example), and yet both lines follow exactly down the fanny. It’s the line (marked with the blue arrow) that is modified, that makes this look so much better.

      Although, honestly when you fit this particular sway back, it’s sweet.

      So here’s the bottom line:
      If you have a RTW,and it fits at the hip when you put a dart across the waist line in back, this technique won’t work. The dart along the waistline isn’t really a good solution either. That means when you’re trying on RTW and you tuck the back in at the waist and it fits, it really doesn’t fit. And if the clerk tells you all you have to do is alter it, she’s after a sale and that’s all. If you try on a larger size, most likely the height of the garment will be off.

      If you make the garment, you get to do all sorts of altering to it – make it in muslin first to check it out, cause once you’ve made it, then it’s done.

      That said, the really better technique to use here is not only to expand the back seam, but also add two waist/hip darts in back. This spreads out the expanse throughout the back and makes for a much softer and prettier fit in back. It also gives you 3 seams, not one or none to tweak so that you can shape them exactly as you want: a little shallower closer to the waist or a little fuller right off the waist or one hip higher than the other (everyone has this), and any other tweaking you might want to do.

      Here’s how to do this:

      Draw a line half way between side and center back and parallel to the straight of grain (which was the old center back before you expanded the bottom). Draw this line to just above the waist (about 1″ to 2″ above waist). Now slash that line and spread out the pattern on the side. You will notice that your pattern will buckle a little along the waist…..just like when you take up that dart along the waist line to make you look better – this is that dart built in, without a seam.

      Working with my brides and debs, this is my favorite (3 seams/darts) to do and it works every time. After you do this, you will most likely want to shape the garment in front by taking in a little under bust to the waist in front to the tummy, but DO NOT TAKE IT TOO MUCH BELOW THE APEX OF THE TUMMY. This will make your tummy look bigger and defeat the whole purpose here. You just want to shape a little and that’s it.

      Now, I can hear it now: “Oh Claire, that’s soooooooooooooo much trouble. Do I hafta do all that?!” OK, it is a little more time. But remember once you do this for your pattern, it’s done. Or you can get something like this or this (check out my Pinterest
      for lots of patterns that I choose that already have lots of fitting darts in them – they are all labeled “Patterns” first, then title). Here’s the thing, if you find yourself battling this alteration, my advice is to get a group of TNT (Tried and True) classic patterns (top, blouse, skirt, dress) and alter those patterns the way you like them. Then every time you need a dress, shirt or top or whatever, the alteration is already done, and you don’t have to alter every pattern in the book.

      OK – so I hope that’s not confusing and most of all, make up that muslin and get this puppy done so you can go on and wear your clothes in style!

  7. Thanks Claire! It was so nice of you to respond and with such great detail. Yes, this makes perfect sense in terms of both adding the center back seam as well as the additional darts.

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