Hey y’all, today we’re going to talk about busts and how to adjust the bust apex on a sewing pattern to match your own measurements. One of the reasons I hear often that women don’t want to sew for themselves is that fit is hard when you have curves. Which is why my goal is to build up a series of posts on how to fit sewing patterns to your body – because it’s really not scary or hard once you get some basic concepts.
One of those concepts is where the bust apex is on a pattern. The bust apex is the most prominent point of the bust on each side of the body, and corresponds roughly with where the nipple is, though depending on individual shape/bra/etc, ie may be slightly higher, lower, or to the side of the nipple. The bust apex is also sometimes referred to as the bust point.
Timeout here for an important message – sewing patterns SHOULD be changed to fit your body, not the other way around. There is nothing wrong with your body when a pattern doesn’t fit you out of the gate, because drafting is done based on sets of average measurements, and almost no one fits the averages for every measurement.
To measure your bust apex height, it helps to have on a shirt with a shoulder seam that sits centered on your shoulder. Then – wearing the bra you would wear with the pattern you are sewing – measure from the shoulder seam to your bust point. Your bra is important here, because some bras (push up bras, I’m looking at you)will raise your bust apex, and wearing no bra is likely to give a measurement that is lower. Gravity and all. So think about what you’re sewing and what bra you would likely wear with it.
It should also be noted here that many bodies require width adjustments to the bust apex on a pattern as well. So once you’ve got your bust point located, take a horizontal measurement from center front to your bust point – that will help with width adjustments.
So now that we know what the bust apex is and how to measure it, how do we find it on a pattern?
If your pattern has multiple darts, you can extend the line through the centers of the darts, and where they cross is where the pattern bust apex is. If your pattern has princess seams, the deepest part of the curve on both the side front and the center front corresponds to the bust apex.
If your pattern only has one dart, and you happen to know what cup size it is drafted for, you can draw a circle with the following diameters and then align the the edge of the circle on the dart tip and the center of the circle on the extended line to find the apex. This is a rule of thumb kind of way to do this, but it generally works.
Once you have an idea of where the bust apex on the pattern is, you can compare that to your own bust apex. And you may find you need to raise or lower it, or lengthen or shorten it, so here’s how to do that.
To raise or lower a side seam or armscye dart
Trace the original dart onto another piece of paper (Tip: use a dark marker that will show up if you place your paper under the pattern). Then measure from the shoulder of the pattern and from the center front to mark where your bust apex is (remember to measure from the seam allowance on the shoulder, and to measure from the same place on the shoulder of the pattern as you did on your own shoulder). Next, move your traced dart up or down until it points at your apex. Retrace the new dart and redraw the seams as needed to align with the new dart.
Now, some methods recommend keeping the dart leg points where they are and then just redrawing the legs so that they point at the new bust apex. I don’t recommend this unless you want to change the angle of the dart.
To raise or lower bust apex on princess seams
Draw a horizontal line and a vertical line in an upside down L shape. Line the pattern up with the top of the shoulder touching the horizontal line and the bust curve touching the vertical line. Measure from the horizontal line down the amount of your bust apex height plus the seam allowance for the pattern. Make a mark along the vertical line to show where you need the fullness to hit.
Trace around the top of your pattern piece, then shift the piece up or down so that the fullest part of the curve matches your mark for the fullness point. Trace the area around the curve, then blend back to the original pattern shape at the bottom of the pattern. Make sure you do this both for the side front and center front. The diagrams above show the bust point being lowered; simply reverse the shifting to raise the bust apex.
To shorten or lengthen a side dart (apex to apex width adjustment)
If your bust points are further apart or closer together than the pattern, you’ll need to redraw the darts so that they point to where your apex is widthwise. To do that, first make any dart height adjustment. Then mark on the pattern where your bust apex is. Use the bust circle table above (in the section about finding the apex on a single dart pattern) to determine about how far the dart point should be from your bust apex based on your cup size and draw a circle with your apex as the center, then redraw the dart legs so that the point of the dart hits the outer edge of your circle while still pointing at your apex.
To adjust apex width if there are shoulder or waist darts
Trace the original dart(s) onto another piece of paper (Tip: use a dark marker that will show up if you place your paper under the pattern). Then measure from the shoulder of the pattern and from the center front to mark where your bust apex is (remember to measure from the seam allowance on the shoulder, and to measure from the same place on the shoulder of the pattern as you did on your own shoulder). Next, move your traced dart(s) left or right until the point(s) is (are) pointing at your apex. Retrace the new dart(s) and redraw the seams as needed to align with the new dart(s).
To adjust apex width with princess seams
This is trickier, as it actually means you need to move seamlines. The seam of a a princess seamed bodice should pass either right through or at the edge of your bust apex depending on the style lines. Start by measuring from the center front of the pattern to mark where your bust apex is. Then you’ll either need to slash and spread the center front (for a wider apex to apex measurement) or overlap it (for a narrower apex to apex measurement) and redraw the curve. Whatever you do to the center front, you need to do the OPPOSITE to the side front, so that you keep the overall circumference of the pattern the same. So if you spread the center front, slash and overlap the side front. And if you overlapped the center front, slash and spread the side front.
When in the fitting process to do a Bust Apex Adjustment
Generally, when fitting you need to first make sure that a pattern will fit around you then fit from the top down, so shoulder before bust before waist on a bodice. Which means that I generally do any full or small bust adjustments first, then raise or lower the apex. HOWEVER, it’s a good idea to mark out where the apex is on the pattern before any slashing/spreading/overlapping for bust adjustments, because if you try to do it after those adjustments you’ll have a harder time finding where the pattern apex was to begin with.
And remember – always make a muslin to check pattern alterations before cutting your good fabric!