Adding A Dart on the Wonder Boy Vest

In this tutorial I will show you how to add a bust dart to a man’s vest pattern

The Wonder Boy vest pattern fits a 36″ chest with a 30″ waist on a male body.  But what if you are neither a male or have a 36″ bust line?  The pattern can be adapted to fit a bust by adding circumference at the bust while creating darts to fit the waist.  Let me show you how.

First you will need these supplies:

  • tape measure
  • ruler
  • colored pencils
  • a fashion ruler
  • tape
  • tissue, or pattern paper of some nature.
  • scissors

You will also need to know your bust and waist measurement.  For the purpose of this tutorial I am using a 40″ bust with a 30″ waist.  Thanks to a client who did a shout out:)

Let’s start with the math – You need to find the difference between the pattern measurement at the bust and waist line and your actual measurements.  My bust measurement is 40″ the pattern is 36″ which gives us a difference of 4″ and the waist is the same so no change there. Because the bust represents the bulk of this difference we need to slash and spread the pattern to accommodate the bust fulness.  If you just add to the side seam, it will fit, but not well, it will look awkward and be uncomfortable.  If you are a C cup you will want to spread the dart 1″, if you’re a B cup -1/2″ Spreading the dart by 1″ will add 2″ to our overall bust measurement- That leaves us with another 2″ to add which will be divided by the 4 side seams.  2 divided by 4 leaves us with 1/2″ that we will add to each side seam(front and back)

We will also need to know where your bust point is.

measuring bust point

Finding that is simple.  Just measure from your shoulder go the apex of your bust.  On my form it is 9″

I am afraid that I cannot in the context of this tutorial give you a varaity of measurement.  But this will give you a more than basic understanding of the process which you can adapt to your measurements.  I highly recommend you make the vest in muslin first to see how your changes worked.  Lets get on with those changes…

robin traced front

click on picture for improved image quality

Start by tracing the front vest pattern piece onto tissue along the stitching line(trust me it’s easier when making multiple changes)

Be sure to mark the grainline.

We are going to spread the dart 1″ at the apex which means we need to lengthen the center front by 1″ as indicated by the red pencil line. This provides the necessary fabric to round over your bust.

Draw a vertical line thru the center of the waist dart extending it a few inches above its point. Take your bust point measurement, ours was 9″ and measure from the shoulder to that line you drew thru the waist dart.

Draw a horizontal line perpendicular to your vertical line that is level with your bust point mark.

Now for the scary part…

robin ladies dart spread


Cut along that vertical and horizontal line you just drew and spread the pattern by 1″ in each direction.

Place a dot 1″ below your apex on the vertical line and place another dot 1″ to the right along the horizontal line.ladies robin draw dart

My apex is marked by the star.  You will now draw in new dart lines as indicated in the above picture.

The waist dart needs to be divided equally between your center vertical line.  We spread the pattern 1″ but there was already a small dart there which originally measured 5/8″.  Dividing 1-5/8″ in half gives you a fat 3/4″ on either side of that center line.  Draw the new dart lines in and extend them beyond the waist seam.

Place a mark(shown in red) 1/2″ beyond the side seam at the armhole.

ladies robin front ss draw

Pin the darts closed.  Folding the excess towards the center on the wasit dart and downwards on the bust dart.

Voila! A bust appears:)

Using your fashion ruler draw a new side seam.

ladies robin add sa


Repeat that for your new waist seam.

Add your 1/2″  seam allowance back all the way around and cut out with the darts still pinned.

That was the tough part, and it wasn’t to bad now was it.  Lets move onto the front lining, back and back lining.

ladies robin transfer darts to lining

If you cut around your pattern pieces leaving plenty of room you should have no problem making the rest of the changes directly on the pattern pieces.  If you want to leave them pristine by all means trace them onto fresh tissue.  As you can see I have placed the original front facing pattern piece directly on top of the front pattern we just added the darts to.  Match up the shoulder and armholes and trace the new side seam, waist seam and darts.

ladies robin back ss

On the back and back lining we just need to add that 1/2 to side seam blending it to nothing at the waist.


There you have it.  Please feel free to ask questions in the comments sections and I will do my best to answer them.  Hope this helps you become a fabulous Wonder Girl Sidekick.


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