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Drafting Basics 1 - Online Course

Seam Allowances

First of all, thank you to all of you who signed up for my online course on how to draft a basic bodice (sloper). I hope you've received the free pattern that I promised to those of you who signed up from the link on this promotional post made by my dear friend Li-Er over at Ikat Bag. If you haven't received it, please click here and I'll make sure to send it ASAP!

I'm in the middle of creating another pattern for the shop which encompasses a lot of testing and re-drafting and re-testing. If you've used my sewing patterns, you'll know that I never include seam allowances into the finished *pattern. I have my reasons for that, and before I get into those, let me go back in time a bit...

Growing up in Singapore in the 70's and 80's, one did not have easy access to paper sewing patterns from the likes of Butterick, et al. In fact, I didn't even know what a commercial pattern looked like until I was well into my twenties and Spotlight opened its first store in Orchard Point in 1995 (remember that, my fellow Singaporeans?). By that time, I was already drafting and sewing my own clothes but foolishly believed a proper sewing pattern would magically improve my game. I chose and cut a size right off the packet info and made the dress...and never wore it. It was too big (despite what the sizing said), the torso was too long, and the sewing instructions were confusing but I doggedly followed them as best as I could because, you know, I'm a product of my society and era. I tried to alter the dress AFTER finishing it but could not fix the too long torso, not without unpicking most of the dress because it was a sheath. And frankly, I couldn't be bothered after all the frustration and disappointment.

But it was a fantastic lesson learnt.

(A few other lessons learnt as well but not relevant to this post *wink*) 

Fast forward a few more years and a change of careers and I found myself staring at another commercial pattern and becoming frustrated that I had to mentally remove the seam allowances in order to get an accurate reading of the sized pattern, while also having to take into consideration the added style and wearing ease. Ugh. My frustration was also compounded by the nagging of my subconscious; telling me that I could have drafted the damn thing myself. But this was before I learnt to love drafting OVER sewing. This was during those frenetic days of DOING and FINISHING because leisure time was LIMITED. So my second experience at using a commercial pattern did not go smoothly either. And I wore that jacket only once because, yet again, the fit wasn't great despite applying the vital lesson learnt from the first attempt.

I concede that had I had greater experience in using commercial patterns, I would have been more adept at altering it. Which begs the question: If I have to alter the pattern anyway, if designers know that chances are great that the pattern must be altered to fit the myriad of body types in the real world, why don't they try to make that process easier then?

Which brings me back to why I omit seam allowances in the commercial patterns I create:

1. One less step when measuring and calculating how much to alter the pattern. 
The seam allowance is just not there to get in the way of your calculations. There are multiple books and online resources available nowadays on altering a pattern for fit. Some even tell you to physically cut away the seam allowance first then add them back afterwards. Why include them in the first place?

2. You need different seam allowances at different seams for different seam types. 
Commercial patterns have a standard seam allowance EVERYWHERE. Usually a whopping ⅝" (1.5cm)! It is so much harder to sew wide seam allowances than narrower ones. Even with a magnetic guide, the cloth wants to slide off the machine bed or bunch into the guide because you are trying to prevent the slippage and therefore over compensate. If you can't increase the foot tension of your machine, this is a common occurrence. Never mind that it is that much harder to sew a neat curve with anything wider than a ⅜" (1cm) seam allowance, which is, in my opinion, still a little tricky but do-able. My recommendation is ¼" (6mm).

3. Less trimming of seam allowances while in the process of sewing.
If you start off with the correct seam allowance, then there would be nothing to trim away. Eliminating a step that is undeniably prone to irreversible damage. I mean how many of us have cut into the bodice/skirt/main section by accident because we just didn't check or more likely, the frigging thing sneaked under the scissors?

4. Advanced dressmakers can easily modify the pattern and seam type.
Maybe you want to replace the butterfly seam with a French Seam. Or maybe you just have that much cloth and can't include the giant seam. Maybe you want to omit the set-in sleeve and draw in a cut-on cap sleeve. Or maybe you want to add an in-seam pocket to the skirt. Without a built in seam allowance, you can quickly 'see' how to add to the pattern or to take something away.

5. Pattern matching is that much easier.
By pattern matching, I mean aligning the paper pattern to strategic parts of the cloth where you want to match stripes or design prints on the cloth. Prints must match on the stitch line, not the cut line. So match up first, then add the seam allowance directly onto the cloth.

I've considered drawing stitch lines on the pattern to show the widths of each seam allowance but that makes stacking multiple sizes in one printout a nightmare to behold. There would be stitch lines crossing over cut lines and guide lines, which will not in any way improve user experience.

Another benefit to adding your own seam allowance is really that you can't help but learn about their technical aspects when you have to add them in yourself. I'm one of those students who must know why I'm doing a thing this way or that. And as a primary school teacher in the past, I tended to tell the kids why as well as how and found them to be much more willing to try it out. It also enabled them to experiment with other ways because they had a better understanding of the processes. 

In my patterns, I include recommended seam allowances and provide instructions on how to sew them. I encourage you to try your own methods and see what really works for you. There is no real prescription to creativity, but in order to start somewhere, it helps to have a launch pad of some sort. So use my recommendations if you need them, or else do as you will. I will continue to leave out seam allowances in the final patterns, unless something happens to convince me otherwise.

As always, happy sewing 😉

*except Marilyn's LBD as it is a stretch dress pattern and the ¼" seam allowance was included with consideration to the stretch factor that has to be calculated when modifying the pattern for fit. Detailed explanations are given in the pattern instructions.


  1. Brava! I also omit SA in all my templates, and not just for garments. In stuffed toys, for instance, having no SA makes it easier to enlarge and reduce the templates. Imagine the nightmare if one enlarged a template-with-1/4"SA and forgot to NOT use 1/4" SA when actually working with the cut pieces? Also, it is just so much easier to cut around a template when you're cutting entirely on the fabric and not trying to hug the edge of a paper pattern. That border of fabric around the paper pattern after you've cut out the piece is such a good visual reminder of what and where to sew later.

    But the main thing, the MAIN THING, has to do with the idea of "matching (or aligning) SA" that is a very common sewing instruction. I wish I could help the world unlearn the idea of aligning SA and instead learn the concept of aligning stitching lines. I see the unfortunate (and avoidable) effects of this when attaching a straight edge to a curved edge, e.g. in a bucket tote where the straight bottom edge of a cylinder has to be attached to the circumference of the circular base. Stitching line -to-stitching line, those two edges match perfectly, down to the mm. But aligning the edge of the SA will throw everything off by entire cms, and people typically report bunching and unsightly gathers and such. So easily avoided in reality!

    OK, getting off my soapbox now. I'll concede that as I, too, grew up in Singapore, you're preaching to the choir, as it were. That said, you've made a compelling argument to those of us who still love our added-SA in templates. I hope we're willing to try something outside our comfort zones and see if it might actually improve our game some. Love this post!

    1. Yes, indeed! 'Walking the seams/pattern' is a term used in pattern-making referring to the process where each seam (on the pattern) is matched against its corresponding other to see if they align. The stitch line is what must match, not the cut edge, or the SA edge as you say.


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