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 course 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! However, if you're interested in the various seam allowances used in industry, there's a very good download available at Threads Magazine, sponsored by Contemporary Fashion Education.

Commercial Sewing Patterns Without Seam Allowances

If you care to explore sewing patterns that don't include seam allowances so you can eventually add your own, 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.)


Last update 10Nov2018

1 comment:

  1. I was wondering about that because I couldn't understand why some patterns didn't include them but you explained it well! I never really trace out my pattern before cutting I usually pin the pattern on top of the fabric and cut around it. And it's frustrating when you have a very detailed curvy pattern piece like corsets do, because tracing that seam allowance just right without distorting the shape of the pattern piece is so much work and complicated. But your way sounds way better actually! like at least you're sure you're stitching on the stitching line that way, which is kinda so so when the seam allowance is included and can also be a hassle on its own. So I think I'm gonna invest in some weights and tracing material, and do your method in the future!


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