I invite you to dive into the wonderful world of ... seam allowances. I've been thinking about writing this article for a while because my beginner students often tell me "it's still practical that the seam allowances are included"... So yes, that's true but... I still have to tell you a few things to moderate this "practical" aspect at the beginning of learning to sew and often a bit less practical afterwards. 

So, let's dive in together! 

1. Definition 

As usual, let's start by defining what we are going to talk about... because basically, what is a seam allowance?

The seam allowance, also called sewing value, is defined as the fabric space between the seam line and the raw edge of the fabric. It is the space between the two lines drawn on your patterns: the seam line (the one you stitch on) and the cutting line (the one you cut the fabric on).

Seam allowance values

As you may have noticed, the value of seam allowances can vary. They are generally 1 cm but you can find patterns with allowances of 0.8 cm, 1.5 cm and sometimes these are expressed in inches for American patterns. 

To ensure you always sew at the right distance, use the markers on the needle plate of your sewing machine. 

Don't have markers on the cutting mat? You can use washi tape (repositionable Japanese masking tape) which you will stick at the right distance on your mat. Then you just have to align with the edge of the washi tape.

What should you pay attention to when buying a pattern?

When you buy a pattern whether it is printed or in a magazine, it is important to check whether they include the seam allowances or not. 

Option 1: the seam allowances are included 

Often on these patterns, the seam line is not drawn, you will only see the cutting line. This means that you will cut your pieces on the drawn line and you will have to assemble your fabric pieces by stitching at the distance recommended in the instructions. 

Option 2: the seam allowances are not included

If the seam allowances are not included, you will have to add them yourself and you can follow the pattern's recommendations or choose the seam allowance values yourself. The important thing is to be consistent when sewing. 

For my part, to add seam allowances I use a Japanese ruler. It is a tool that has become indispensable to me (to the point that I wondered how I managed before 😅) after my pattern making training. We also sell them in the shop because they are not always easy to find. 

Why having seam allowances in the pattern can be practical or, on the contrary, annoying?

As my beginner students say, it is practical to have the allowances included... indeed, you just have to cut your pieces without adding seam allowances... but this also means that the seam allowance value is imposed and if you want to change it, you will have to modify the pattern. 

Sometimes, you prefer a 1.5cm seam allowance rather than 1cm or you want to make a flat-felled seam which will require about 1.5cm whereas the included value is 1cm... I admit that in this case it annoys me that the sewing lines are not drawn on patterns with included seam allowances.... 

When you have a pattern without included seam allowances, we have the sewing lines drawn. This is very advantageous when you want to:

• grade the pattern, that is to say increase the pattern. For example, you would need a size 50 but the pattern goes up to 48. Having the sewing lines makes it easier to increase the pattern.
• transform the pattern. For example, you have a sweatshirt with classic sleeves and you would like to transform it into raglan sleeves, it is perfectly possible if you work with the sewing lines. 
• choose the seam allowance values depending on the pieces. For example, it is not uncommon when I sew a men's shirt to add different seam allowances depending on the pieces. 
• ...

Okay, but what do I choose now? With or without seam allowances?

It all depends on your level, your tastes, and personal preferences.

If you are a beginner, it is unlikely that you will start by grading or transforming your patterns... So included seam allowances are really very practical. 

When you progress in sewing, you might want to add your creative touch, make pattern modifications, choose your seam allowance values... and for that, nothing beats having the sewing lines and therefore a pattern without included seam allowances! 

Personally, as you have understood, I prefer a pattern without seam allowance but this is largely due to my sewing experience as well as my love for pattern making and beautiful finishes (I like being able to choose the seam allowances depending on the type of sewing I am going to do and even more so when I sew lingerie)... so I would say it's really a matter of personal taste but also expectations towards this wonderful creative hobby that is sewing!  

So get your pencils, Japanese ruler, needles, and washi tape ready! 

Happy sewing!