Old school: A shoulder dart for nerds


In one of my previous posts I described a shoulder dart calculation method. It is, of course, one of many, and possibly one of the easiest. Today I’d like to tell you about another method, much more complicated and for this reason much more interesting (to me, anyway).

This pattern drafting method was developed by an organisation called “Central Institute of Scientific Research of Apparel Manufacturing” in ex-USSR. The development of this method took 20 years (1959-1979) – that’s right, a team full of professionals had been working on it for two decades. Needless to say, it is complicated. I have drafted a couple of blocks using this method recently and the fit was great, but make one mistake and the whole thing is ruined. Here is how you calculate and draft a shoulder dart using this method.

To start with, you need a few body measurements, plus two special measurements that hardly anyone has heard of. One is called the Torso position, another one is the Shoulder blade separation.

The Torso position measurement determines how round your shoulders are. To take this measurement you have to stand next to a wall (keeping your usual posture), with your back just touching the wall.

Next, get someone to measure the distance between the wall and the nape of your neck. If you are round shouldered, the distance will be 7-9 cm, if you are closer to a standard figure, then 5-7 cm, and if you are overly straight, then 3-5 cm.

Now to the Shoulder blade separation measurement. This one is measured horizontally between the angles of your shoulder blades – the two points that are usually sticking out.

Donatello shoulder sep measurement

Measure carefully, because this one determines the angle of the shoulder dart. So, obviously, according to this method, the shoulder dart is not parallel to the centre back seam.

One more, more familiar measurement you’ll need is Back length I, taken from the seventh vertebra to the waist level.

And on top of that there is a special little thing they call “back armscye easing factor” (I referred to it as “fabric easing” in my previous post). This Easing factor is 0.5 cm for a jacket and 1 cm for a coat.

And so, let’s draft.

First we draw a CB line from the waist level up and mark point A.

Then we find point Y (AY= 0.4*Back length I) and draw a perpendicular, this is your shoulder bade level.  On this perpendicular we find point Y1. Y-Y1 = Shoulder blade separation measurement/2.

Then we find point A1. A-A1= Torso position*0.1. Join points Y and A1. We’ve made the first step to stop the neckline gaping at the CB, but we don’t stop here.

Draw the back neckline and the shoulder slope line. Mark point Q 4 cm away from the neck point, along the shoulder slope.

Join point Q and Y1. Draw a circle with a centre in point Y1 with a radius of 11 cm (a fixed measurement for this draft). Mark the point, where the arc crosses line QY1, call it Y2. Along this arc measure the calculated dart width using this formula: Torso position/4 – Easing factor. Mark point Y3.

Draw a line from point Y1, through Y3 and continue up to the shoulder slope line. Mark point Q1 where the line intersects with the shoulder slope line. Q-Q1 is your shoulder dart width. Now, shorten the dart, so its length equals three dart widths. Dart length = Dart width*3

shoulder dart draft2

And here it is, the shoulder dart. I warned you, this method is full on, and if this is what it takes to calculate the shoulder dart, imagine what the rest looks like.

Although you might not want to do all these calculations, there are still several interesting points that can be learned from this method:

  • The Torso position measurement is a very useful thing. Taken into consideration this early in the draft, it will help you avoid the back neckline and the back armscye “gaposis”. Even if you are not going to measure it, evaluate it visually to decide on your shoulder dart size (see my previous post).
  • The dart points towards the protruding point, just like the bust dart does, and the protruding point position is measured and calculated. Makes sense.
  • Shoulder blade level calculation. This level is where the most of your back width is. A great formula to remember.
  • 1:3 shoulder dart ratio is something that must be remembered to avoid those funny pointy shoulder darts.
  • The “back armscye factor” or “fabric easing” is a small but important thing that makes the back of your armscye follow the curve of your body instead of sticking out. It has been mentioned in two draft methods so far, so it is worth remembering.
Lena Merrin
Lena Merrin

A dressmaker of many years, I enjoy drafting patterns and create custom garments.

7 thoughts on “Old school: A shoulder dart for nerds

  1. Wynn says:

    This is so interesting, Lena. I love this too! This is really ‘lost’ info. So glad you’re putting it in the public ‘forum’.

  2. Vickie says:

    I’m not sure if I missed this in your last post, the calculated adjustment from Y to T. Does this help balance the waist reduction between the center back, darts, and side seams? I’m going to draft this since I have a narrow upper back with very square shoulders and a sway back issue. Not to mention the huge amount of increase for the hip.

    • Lena Merrin
      Lena Merrin says:

      Hi Vickie, no, YT is shoulder blade level only, it is not related to the back darts distribution.

      • Vickie says:

        Thanks for the feedback Lena. I am going to use this draft because I still think it will help on my hunt to find answers, to my fitting issue. Looking forward to the next post!

  3. margk says:

    Lena, you’re so right – there are some very interesting drafting points to take from this. I must admit to being more and more amused as you progressed through each step of this. Love it!

  4. Lesley says:

    This looks really fascinating Lena. I do hope you get to sleeves and armscyes in general. Thanks for the insight.

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