June 21, 2022
Smaller Bust Adjustment (SBA) for a Top with a  Bust Dart - Scenic, Vista, Plains

Here are simple, step-by-step instructions for adjusting a top shaped with darts to fit a smaller bust.  We're demonstrating the adjustment using the Scenic Top - the adjustment is the same for the Vista Top and the Plains Dress

If you find that tops tend to sag over the bust, but fit well elsewhere, then this adjustment will help you to tailor the fit exactly where you need it.  We also discuss changing the position of the bust apex based on your specific measurements - sometimes the adjustment may be as simple as moving the dart up or down so that it sits at the right position for your body.  

Making pattern adjustments may seem a bit daunting at first, but the effort is completely worth it to achieve a beautiful, handmade garment with a custom fit.

Materials

Gather some basic materials to adjust the pattern pieces:

  • Top Front pattern piece (we're using the Scenic Top)
  • measuring tape
  • scrap paper
  • tape
  • ruler
  • pen/pencil
  • scissors

Measure

To determine the size of adjustment necessary, measure your upper bust and full bust. 

The upper bust measurement is taken around the body, with the tape snugged up to the underarms, and above the breasts. 

The full bust measurement is taken around the fullest part of the breasts.  

Diagram demonstrating how to measure upper bust and full bust for sewing

Compare your body measurements to the size chart in the pattern tutorial.  

For example:
  Size H Your body measurement
Upper Bust measurement 34" (86cm) 34" (86cm)
Full Bust measurement 36" (91cm) 35" (89cm)

In this example, the full bust is 1" (2.5cm) smaller than the size chart, so an SBA is needed.  

Pattern adjustments will be made to half of the garment (because the pattern piece is cut on fold), so you will remove half of the 1" (2.5cm) difference = 1/2" (1.25 cm). 



Bust Apex

The dart is intended to “point” to the fullest part of the bust or the bust apex when the top is worn.

The bust apex is marked on the pattern. It is a good idea to measure your own bust apex to make sure the bust dart ends up in the correct position for your body. 

To find your personal bust apex, measure from the outside corner of the body on the shoulder bone (the position where a shoulder seam line would sit) to the centre of your bust - this is the part that points out the most. Note that the bust apex is not necessarily the same as your nipple position. We recommend taking this measurement while wearing underwear similar to what you would wear under the garment you are making. 

When taking a comparison measurement on the pattern it is taken from the stitching line on the outside corner of the shoulder seam to the bust apex point marked on the pattern.

Diagram demonstrating how to measure bust apex position for sewing

Check your measurement against the pattern.

Diagram demonstrating how to measure bust apex position on a sewing pattern

Keep a note of the difference between your bust position versus the pattern.  For example:
 Pattern = 9.8" (25cm)
Your Bust Position = 8.8" (22.5cm)
Difference = 1" (2.5cm)

Small Bust Adjustment

Adjust pattern pieces

1.  Begin by drawing cut lines on the Front pattern piece:

a. Line parallel to Centre Front (CF) from the hem to the end of the dart (line a on diagram below).
b. Line at right angles to CF from the dart end to CF line (line b on diagram).
c. Line through centre of dart to dart point (line c on diagram).
d. Line from dart end to stitch line of armhole seam (line d on diagram). 

Diagram demonstrating how to do an SBA (Small Bust Adjustment) on a sewing pattern with a bust dart

2.  Cut the pattern along these lines, keeping the pivot points intact at dart end and armhole seam (see diagram above for location of pivot points).  If you accidentally snip through the pivot point, use some tape to create a hinge.  

Be sure to mark the original dart end so you don't lose it in the changes. This is VERY important. 

Diagram demonstrating how to do an SBA (Small Bust Adjustment) on a sewing pattern with a bust dart

For the following steps, it is a good idea to position your pattern piece over a larger piece of paper, so that once the adjustments are made, you can cut around the entire finished piece.  This prevents things from shifting around so much.  

3.  Secure the top section of the pattern piece with tape, then draw a line extending the CF edge below the pattern piece. 

Diagram demonstrating how to do an SBA (Small Bust Adjustment) on a sewing pattern with a bust dart

Now, apply your full bust difference to the pattern.  In our example, the full bust difference is 1" (2.5cm).  Divide the difference in half: for example 1" (2.5cm) / 2 = 1/2" (1.25cm) because we are working on half of the front piece.

Slide the side section in by your calculated difference: our example is 1/2" (1.25cm).  Let the dart and armhole pivot - the side will move up and the dart will close.

Diagram demonstrating how to do an SBA (Small Bust Adjustment) on a sewing pattern with a bust dart

4. Slide the centre section up by half the amount the side section slid in on the previous step, so 1/4" (6mm), along the CF line you drew earlier.  

Diagram demonstrating how to do an SBA (Small Bust Adjustment) on a sewing pattern with a bust dart

5. Redraw the dart stitching lines so that they meet at the point of the original dart end (note that for a Small Bust Adjustment, the dart end may slide underneath the pattern piece).

Diagram demonstrating how to do an SBA (Small Bust Adjustment) on a sewing pattern with a bust dart

6. Blend the hem and smooth the armhole if needed. 

Diagram demonstrating how to do an SBA (Small Bust Adjustment) on a sewing pattern with a bust dart

 

7. The adjustment is complete, however, if the location of your Bust Apex is different than the pattern, we'll continue below with a few more steps.  

Diagram demonstrating how to do an SBA (Small Bust Adjustment) on a sewing pattern with a bust dart

 

 

Bust Apex Position Adjustment

The dart should be positioned so that it points directly towards the Bust Apex.  It may be necessary to move the dart up or down so that it is positioned correctly.  This adjustment may be all that is needed to improve the fit of a top with dart shaping.  

1.  Cut two lines at right angles to the Centre Front Line, above and below the dart. 

Diagram demonstrating how to adjust the bust apex position on a sewing pattern with a bust dart

2.  Slide the darted section down or up by the difference.  In the example above, we calculated the difference as 1" (2.5cm) higher, so we will slide the piece up by that amount.

Diagram demonstrating how to adjust the bust apex position on a sewing pattern with a bust dart

3.  Blend the side seam on both sections.

Diagram demonstrating how to adjust the bust apex position on a sewing pattern with a bust dart

 

4.  Your pattern piece is now ready to use!

Remember, we always recommend sewing a muslin to test out your pattern adjustment before cutting into your fancy fabric.  

If you have any questions about sewing or making adjustments to the Scenic Top, please feel free to join us in the Twig + Tale Treehouse Community or the Twig + Tale Chat Facebook group.

Smaller Bust Adjustment (SBA) for a Top with a Bust Dart by Twig + Tale

Read more pattern adjustment tutorials here: