Hello everyone! In preparation for my new pattern I wanted to include notes on how to do a Full Bust Adjustment and a Small Bust Adjustment. I found a great FBA tutorial over on Curvy Sewing Collective but couldn’t find an independent tutorial I liked on SBAs for a 2-dart bodice. So I’m making my own!
I’m using the bodice piece from my upcoming pattern (which is why it looks like a big triangle is cut out of the bottom left corner) but this will work on any bodice with a side and a waist dart.
How to figure out if you need a Small Bust Adjustment?
- Do you know that you have a small bust? Like, smaller than a B-cup?
- If you make a muslin of your bodice does it fit well in the shoulders but bag out in the bust?
- Or does your muslin fit well in the bust but is too tight in the shoulders and arms?
- Does the waistline bag out in the front and the side seams angle backward (too much length and width in front)?
- On pattern size charts does your bust measurement usually fall under a smaller size than your waist measurement?
You will need:
- Tracing paper
- Clear ruler
- Tape measure
Start by measuring the fullest part of your bust in whatever undergarments you will wear with your dress. Make note of this number.
Select which size bodice piece to work with based on your waist measurement. The bust size will likely be larger than your bust measurement.
Now for some math: Say your measurements are 32″ bust and 27″ waist, and the pattern piece you cut out is sized for 34″ bust and 27″ waist.
Subtract your bust measurement from the pattern’s bust size: 34″ – 32″ = 2″
2″ is how much you need to remove from the front bodice piece total. But because most patterns use half-pieces either cut out twice or cut once on the fold you need to divide your 2″ in half, or 1″ reduction per side of the front bodice.
(Alternately, if you’ve already made a muslin that fits well in the shoulders and waist but is baggy in the bust, you could pinch out the extra fabric from the center front, measure that, divide it in half, and use that number for this tutorial.)
Adjusting the Front Bodice Piece:
Trace your bodice piece on another sheet of paper. Be sure to label any notches, darts, grainlines, etc.
Pink Line: With your ruler and pen draw a straight line from the center of the waist dart up to the point of the dart and extending a few inches up beyond the dart point.
Blue Line: Draw another straight line from the center of the side dart through the point of the dart and extending out a few inches beyond the dart point.
The point where these two lines intersect is the bust apex (fullest part of the bust). Mark the apex with a dot.
Purple Line: Starting from the apex dot draw a straight line extending to about 1/3 of the armhole curve from the side seam. Mark a dot where this line intersects with the seam line (in this case 5/8″ in from the edge of the pattern piece)
Orange Line: Lastly, draw a horizontal perpendicular to the Pink Line, extending from about the halfway point of the Pink Line over to the center front.
(these four sections of the pattern are labeled 1, 2, 3, and 4 in the illustrations)
With your scissors cut along the Pink Line starting from the waist to the bust apex point, pivot, and continue cutting along the Purple Line, stopping at the seam line dot.
Next, beginning from the side seam cut along the blue line stopping just before reaching the apex point. DO NOT cut pieces 1 and 2 apart. They should be hanging on just barely to each other at the apex point.
Remember that 1″ number we came up with earlier? Draw a vertical line parallel to the Pink Line, 1″ to the right (solid Green Line).
Slide pieces 1 and 2 over so that the Pink line on piece 1 matches up to the Green Line. This will cause the bust apex point to shift up and over so the waistline of piece 1 will be higher than it originally was. This also makes that side dart narrower because piece 2 slides slightly on top of piece 1.
From here we need to cut along the Orange line and shift piece 4 upward, slightly overlapping piece 3 so that the waistline will be level.
Tape all the pieces together.
Redraw the darts from the seam lines up to the original dart points (in red). True up the edges of your darts by folding them together like you would if you were sewing, fold them down or to the side, and cut off any excess paper.
If necessary, smooth out the armhole curve line (also in red).
Trace your new pattern piece and add all darts, notches, labels, etc.
So what changed when we did this SBA? Well, the darts are thinner. The center front line is slightly shorter but the side and waist seams remained the same length. We also reduced width in the pattern piece without altering the neckline or shoulders. The armhole curve looks a bit different than when we started but should be the nearly same overall length.
And you’re done! Doing a SBA won’t necessarily fix all your fitting woes but it’s a good place to start.
I hope this tutorial helps some of the slimmer busted gals out there. SBAs probably aren’t as common as FBAs but everyone deserves to get the best fit they can no matter their shape.