Seam Allowances on Sewing Patterns: Yea or Nay?

Do you prefer sewing patterns with seam allowances or patterns without? I love reading the various discussions about this and seeing how strongly some sewists defend their positions. (ETA After I posted this on Instagram, I received some good answers in the comments. You can read them here.) I have strong opinions about seam allowances, too. Which side of the debate am I on? Well, both actually... so maybe this means my opinions are not that strong. They are clear, however, and I can tell you exactly why sometimes I work with a pattern that has seam allowances included and sometimes I don’t.

For context, I mainly use patterns that I draft myself based on my body block (which I also drafted). I don't consider myself a pattern maker, but I’ve had enough pattern making and draping classes and experience to draft basic knit patterns for myself or from specifications. I do, however, often test commercial patterns to see how my fabrics work with them.

The Case Against Included Seam Allowances

People ask “why would you go through the bother of using a pattern without seam allowances when you’re just going to have to add them later?” My answer is that there are so many things you can do before you add them!

If I have any question whatsoever about whether a pattern will work with a particular fabric, I trace the pattern (with thread or chalk) onto the fabric without a seam allowance and then estimate my seam allowances while cutting. This gives me wiggle room to fix fit problems.

For example, if I’m unsure of fit in a certain area, I’ll cut the seam allowance a little wider. My back, for instance, is relatively wide. If the fabric I’m using isn’t the stretchiest, I’ll sloppy cut my back armholes with a slightly wider seam allowance so I have enough fabric to play with if I need to go back in there add more width after sewing. It’s “quick and dirty” insurance, in case things seem too tight later. This all works easily, so long as the original sewing lines are marked clearly. Once I’m happy with the seam placement (and the fit), my final seam allowance will be determined by the seam finish, depending on the type of sweater knit and style.

Another advantage is that paper pattern adjustments are quick and easy to figure out if those darn seam allowances are out of the way. When using a commercial pattern, seam allowances need to be removed before adjustments are made anyway, so starting with a pattern that doesn’t have them saves a step.

I don’t sew mockups when working with sweater knits, since at this point I'm comfortable and familiar with the way many knits behave. They're generally very forgiving, though they all act a little differently. Even when a commercial pattern size is selected correctly, working with an inexpensive knit fabric to test the fit can be a waste of time. It’s extremely difficult to judge fit when using a knit that’s different from the one you’ll use in your garment -- sometimes you get a bad surprise! However you do need to make sure the pattern is close to fitting you before you cut into the “good” fabric.

Choosing the right pattern company helps. Some people find a particular company’s patterns more closely match their shape. If you’re lucky enough to find such a pattern company, it will usually decrease the number of pattern adjustments required. Sometimes, however, significant adjustments are still needed. In my upcoming online class How to Cut and Sew a Sweater I help people choose the best pattern size for a starting point. We then adjust the sewing pattern based on actual body measurements, the stretch of the particular fabric, and ease (as needed). Initial adjustments are done on the paper pattern, as many as necessary, before cutting the fabric. Seam allowances are then left wide enough for any secondary adjustments.

The Case for Included Seam Allowances

When ready-to-wear, cut and sew sweaters are made, the final pattern includes the seam allowances. If I were using a tried ‘n true pattern with a tried ‘n true fabric, no question, I want my seam allowances on that pattern! If I'm making a quick sweater, perhaps one that's decidedly slouchy or oversized, that I’m going to whip up on the serger, I want a seam allowance there as well. Basically, when I know there are no adjustments that need to be made, seam allowances on the paper pattern increase speed and accuracy.

Now remember, I’m talking strictly about sweater knits and maybe a few other types of knits. I probably would not be so carefree with a woven fabric. I said “probably”. Honestly, I don’t know, since I haven’t sewn any non-knit garments for several years now!

Commercial Sewing Patterns Without Seam Allowances

If you care to explore sewing patterns that don't include seam allowances, below are a few pattern companies outside the United States that publish such patterns. (I'm pretty sure all US based companies include seam allowances.) If you're going to sew a sweater, be sure the pattern is designed for knits.

  • BurdaStyle (Downloads and magazine patterns only. Burda patterns sold in envelopes to the US market have included seam allowances.)
  • Ottobre
  • Neue Mode
  • La Mia Boutique (In Italian, but my browser offered to translate it for me.)


A Roadmap for Improved Sweater Knit Seams

An almost invisible seam on my cut and sew cable sweater
Seams? Wasn't that the topic of a post last summer? Why, yes it was!

Since it's the number one question I get asked about sewing sweater knits, I think it deserves a quick revisit. Think of this post as “How to Smooth Sweater Knit Seams – Part 2”.

The first real challenge many of my students face in the pattern making module of Introduction to Knitwear Design, a class I teach at Fashion Institute of Technology (F.I.T.), is sewing a smooth seam, a seam that lies flat and doesn't ripple. The students spend the first six weeks of the class drafting various basic sweater slopers. Around the seventh week, students must actually begin cutting and sewing sweater fabrics, one of the necessary steps on the way to understanding the properties of the fabrics firsthand and creating their own designs.

Though we start with the basics (stitching together simple squares of sweater knits), the stretch and (sometimes) slow recovery does take getting used to. This can be especially true for those who are very skilled at sewing woven fabrics. Learning to sew sweater knits means learning new skills and practicing. Fortunately, most people can get quite comfortable sewing a variety of knits in a couple of concentrated hours or less!

While my F.I.T. students sew on industrial machines, domestic machines are usually very good with sewing sweater knits as well. I've discussed machine set up and special accessories before in several posts on this blog. This time I've collected everything into a printable roadmap for troubleshooting seams in a home sewing environment. On the roadmap (and it really is a roadmap) I've outlined the route I usually take with stops along the way. Feel free to skip some stops depending on your tools, or take another route entirely. Newsletter subscribers have already received links to this download. Others can download a copy by clicking below.

Before you start a sweater project you need to figure out what settings work for your fabric in all the orientations it will be sewn. While it may seem like a lot of information, you can work through it methodically with fabric scraps. Once you've practiced and found the correct set up, you can proceed to sew your garment without seams that ripple.

First, consider all the directions in which your fabric will be stitched together:
  • Lengthwise to lengthwise, as for side seams
  • Lengthwise to crosswise, as in sewing bands (cuffs) to sleeves
  • Crosswise to crosswise, as in sewing a hem band to the bottom of a sweater.

Test each of these scenarios and note the stitch length, stitch width, and tension that yield the best seams.

Sewing a set-in sleeve or a neckband requires sewing in all directions, including on the bias. I don't recommend changing settings partway through those seams unless the fabric is really, really, tricky!

My advice, if you're new to sweater knits, is to take your time with basic elements to get them the way you like them. Then expand your skills at your own pace. Practice makes improvement!

Below is a quick video from last Saturday's sewing #OnSaturdaysWeSewSweaters where I go through some of these steps for my current personal project, a cardigan in Washington Square wool.

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Plans for a Washington Square Cardigan

First, a tip of the hat to Erica Schmitz and MyBodyModel! Though the croquis builder app is still in development (as far as I know), Kickstarter backers received a PDF download of several realistic body types. My quick illustration above for the Washington Square cardigan was "hung" on one of those figures, and I made the croquis layer invisible in the final rendering. When designing for myself, working with a figure closer to my own was so much better than working with the 9-head tall figure I learned to draw a long time ago in fashion sketching class. Won't it be fun (and productive) being able to make preliminary designs for myself on a digital mannequin with my real proportions!

In the meantime I did enjoy creating a digital, stylized version of the cardigan I designed (in my mind) over a year ago and have yet to make. What's not shown in the illustration are the embellishments I'm planning. I consider Washington Square a textured plaid with the usual vertical and horizontal intersecting stripes, represented here as ribs and ripples instead of color. I thought it best to give the embellishments a try in real life first to see what's possible with this fabric.

My goal is to enhance the plaid aspect with simple machine embroidery over a very small portion of the cardigan, perhaps near the bottom. Brown seemed like a good “neutral” background for the other colors I want to feature: red, orange, and yellow.

As always, I’m working with pre-washed and air dried wool. I tried these embellishments with and without wash away stabilizer. I may end up using leather to bind the edges, similar to the zipper ripple jacket I made several years ago. Otherwise, I’ll see what kinds of knit fabric I have available for binding.

Using the contrasting color as the top thread and matching thread in the bobbin
Experiments in stitch length, width, and tension
Now with stabilizer pinned to the back. Turns out stabilizer doesn't make much difference with this fabric.

Got the basic hang of it now, but more experimentation is needed.

Some of the above pics were previously posted on Insta Stories #OnSaturdaysWeSewSweaters. Keeping a day to sew is my personal challenge, but feel free to use the hashtag if the occasion arises! I watch in awe as sewists post their #makenine goals for 2018 on Instagram. Planning personal projects so far ahead just doesn’t seem to work for me. Instead, I discovered I can be more efficient by really taking the time to thoroughly plan a single project.

I've learned the hard way that changing a design element in the middle of a project wastes time, energy, and fabric! I can't tell you how many times I've changed necklines mid construction, only to go back to the original design. I should know better, but once I get started, a million other ideas pop into my head, and I’m anxious to try them. I must learn (and remember when I’m tempted by those ideas) that I can always use the rejected design elements on future projects, if I still want to give them a try.

Anyone else come down with idea-overload midway through a personal project? Do you go with the urge and try out the ideas?