When fitting a sewing pattern, you typically check standard measurements such as the bust, waist and hip — all measurements of circumference. But there’s another that’s critical to getting the perfect fit: vertical dimension. This measurement isn’t usually marked on most patterns, but you should measure and adjust your patterns for it (in both dimensions, actually) to get the fit you need — especially if you’re plus-size or full-busted.
The two dress forms pictured above show the potential need for vertical adjustment on sewing patterns. The light pink form shows how bust depth, which is the distance from the top of the shoulder to the bust apex, is considerably longer with a plus-size or full-busted figure. The horizontal line marks the bust apex on both dress forms, and that’s the point on your pattern where you want the maximum fullness to accommodate the curves.
Imagine a pattern with bust darts that finish near that apex — clearly, they need to be closer for the less full bust and further away for the more full bust. Which means the full-busted form needs more length in the front of the garment to reach the waist. Here’s how to get that extra length.
Good to Know: Often, wrap-style dresses or tops don’t include a side dart, so the below tutorial is a way to adjust the pattern front to create extra length when needed.
How to Make a Vertical Adjustment
What You Need
1. Evaluate the Pattern
Above is a front bodice pattern piece of a mock wrap front with shoulder darts. The bust apex is indicated on the pattern as the small circle with the +. The center front is also marked, and that should be transferred to your pattern so the wrap overlaps properly. There is no side bust dart, but that will be added to create shape and allow for the longer front measurement from shoulder to waist.
2. Make a Muslin
The test muslin of the pattern shows the circumference seems to fit around the body and be where you want it. But the issue with the bodice’s length is clear: the yellow dots represent the bust apex on the pattern, and they are about 2″ higher than the actual apex of the form shown by the upper ribbon.
The bodice is also pulling upward under the bust, so the garment waist will not be in the right place. To fix this, measure the distance between the pattern mark of the apex and the actual apex. This will be the distance the pattern will be lengthened over the bust.
Then, measure the distance between the bottom of the bodice and the waist. If that’s more than the difference you’ll be adding at the bust, you may want to add a little more at the bottom edge as well, or deepen your seam allowance to permit some adjustment when you sew the top and bottom together.
3. Split the Pattern Piece
Draw a horizontal line across the pattern, either through the apex or just under as shown. Make sure that line is perpendicular to the grainline. Add a few vertical lines across this horizontal line — these will be used to connect the pattern piece after you split it.
Cut the pattern piece in half using this line.
4. Lengthen the Pattern Piece
Insert a strip of paper between the split pattern pieces. In the example above, we added 2″ across the bodice front. Line up the vertical lines to keep everything even, including the grainline.
5. Adjust the Front Cutting Line
By adding the 2″ in the middle of the bodice, the long front edge will become a bit jagged. Smooth this edge by redrawing the cutting line, splitting the difference above and below the inserted piece. Trim off the excess.
6. Add a Dart
With the added length, the front bodice is now 2″ longer than the back bodice piece at the side seam. To take up that difference, add a side bust dart . This kind of dart is really helpful to get a good fit on a full bust, so don’t be afraid to add one where none exists.
The dart point should be about 1½” to 2″ away from the bust apex. To make it more pleasing to the eye, slant your dart upward instead of making it completely horizontal.
Pro Tip: Pin your paper pieces together and test on your body. You can pinch out the extra to see just where the side dart should go.
Make sure the front and back bodice seams are trued up, then you are ready to try a second muslin.
7. Test the Adjustments
Before you begin sewing, test your adjustments on a new muslin to see if they work. The one pictured above has the the bodice length adjustment and a side seam bust dart added. The bottom of the bodice hits at the waist and retains the ease and blousing of the pattern design. The new dart creates fullness where it’s needed over the bust, and allows the fabric to drape instead of pulling the waist seam upward.
With these adjustments, the bodice drapes nicely and will be much more comfortable than it would have been without the front length adjustment. Then you know the bodice pattern piece is ready to use with your fashion fabric!