I’ve heard from a lot of people that they find the idea of doing a bust adjustment on princess seams horrifying. Honestly, it’s actually not that different than doing a bust adjustment on a darted bodice – but personally, i feel like you get a smoother end fit with princess seams. With the release of my new Karri dress, I knew many of you would be wondering how to tackle this adjustment, and also whether in fact you actually need one. But never fear! You can do it, i promise.
Here’s the deal. Most patterns are drafted for a B cup. I know that’s probably upsetting those of you who aren’t B cups, but the unfortunate truth is that patterns need to be drafted to some sort of base standard, and most pattern companies (like mine) draft for a B cup. What does this mean for people who aren’t B cups? Well, you’ll probably need to alter your pattern to get the right fit over your bust.
So how do you know if you need to do an FBA on your pattern? There are a couple of ways you can tackle this, but here is my easy method. You know that size chart you get on the back of your pattern envelope? If you find that your bust measurement falls in a larger size column than the rest of your body – then you’ll probably need to do an adjustment. If you’ve already made a muslin, you might notice you need to do an FBA because things just aren’t quite sitting right in that area. Some symptoms may include:
- the waistline being higher at the front than the back of your bodice
- the fabric pulling around your arm syce
- an inability to close the bodice of your dress around your bust, even though you can over the rest of your body
- the apex hitting you too high
// CALCULATE //
Calculating the size of your adjustment is really easy if you use this simple method. Just figure out what size you would be if you used your bust measurement – then compared it to what size you would be if you used your other measurements to determine your size. The difference between these two measurements is the size of your FBA.DRAW SLASH LINES
- First note the notch on the CF of the Side Bodice pattern. On Karri this conveniently corresponds to the bust apex. Mark a point 5/8″ (1.5cm) in from this point, as we don’t want to adjust in the seam allowance.
- Next draw a line from this point to your armsyce, about 1/3 of the way in. Conveniently, the notch on the armsyce are pretty much 1/3 of the way up. Make sure that you mark 5/8″ (1.5cm) in from the armsyce edge.
- Draw a line down from your centre bust straight down – alone the grainline. This line should be parallel to the grainline marking on the pattern. Unfortunately this line has ended up in the seam
- Draw a short line perpendicular to line 3 . This line should hit the Line 3 and edge of the pattern
CUT & SPREAD
Cut Line 3 from the bottom to the centre bust, then along Line 2 till you reach the dot you marked near the armsyce, making sure not to cut completely through the pattern paper at the armsyce. Also cut the seam allowance towards the seamline dot. We need to leave a little bit so that we can use it as a hinge.
Next cut Line 1 from the side seam towards the centre bust. Do not cut completely through the pattern paper at the center bust. Once again, we want to leave a bit of paper to use as a hinge.
Spread the centre slash line (line 3) by the size of your bust adjustment. Make sure you keep the slash lines parallel (ie keep the distance the same all the way down). For this example i’m going to use an adjustment of 1″ (2.5cm) as calculated above.
Now we need to fix the waistline. The centre front is now slightly shorter. Cut along line 4, cutting completely through – then move it down till it is in line with the new waistline. I like to use my ruler to keep it straight.
Put some pattern paper underneath, and tape everything together!!
Now we have made our adjustment, but we’ve added a dart at the side seam, which we don’t want. So we need to eliminate it, but keep the extra ease.
Extend line 1 all the way to the centre front of the pattern.
Cut open the dart, and also cut along the new line we have created at the centre front, being careful to leave a small amount of paper to act as a hinge.
Close the side seam dart and tape together. You’ve now moved the dart excess to the centre front!
Having a look at our adjusted pattern piece you can see that we have made the side front pattern piece longer. This means we will also need to lengthen the centre front pattern pieces. On a standard princess seam dress, the adjustment would look like this. Measure the additional length you added to the side front panel, and transfer these to the centre front pattern piece. First mark your cut lines, then spread them by the appropriate amounts, tape extra paper in the gaps, and cut out your new pattern.
//KARRI SPECIFIC ADJUSTMENT//
For Karri the Front of the bodice is made of 3 panels. The easiest way to extend the front of the bodice, is to adjust the front pattern piece, labeled number 1 only. Since all of our adjustments happened below the bust notch on pattern piece 4, we can essentially ignore pattern piece 2, the front top. However please keep in mind that though this is the simplest way to adjust the pattern, it will mean that the horizontal bust seamline in the pattern will sit higher than the bust apex. In the original pattern this line goes directly through the bust apex. You may like this look with the style line higher, but if you prefer the seam to hit across the bust apex as in the original pattern, than i would suggest a further adjustment.
Choose a new notch location on pattern piece 4, that corresponds with the bust apex. You will need to test this on yourself, but for this example I’m using the top leg of the adjustment dart.
Cut off the seam allowance at the notch on pattern piece 2. Discard the seam allowance, and tape pattern piece 2 on top of pattern piece 1 so that the notch lines up. Draw the new notch location on pattern piece 1, in this example it will be the top cut line.
Cut along this line. These are your new pattern piece 1 and 2. Don’t forget to add seam allowance to the top of pattern piece 1, and bottom of pattern piece 2.
//FINAL NOTE//
Now one last note.In this tutorial I didn’t want to complicate things, so I have shown the standard method for an FBA. This standard approach will always result in making the waistline wider in addition to the bust. This means that you will more than likely need to remove some width from the side seams of pattern piece 4 to maintain your correct size. My personal method for this differs very slightly. Instead of maintaining the entire bust adjustment for the full length of bodice, i keep the bottom edge of cut line 3 hinged, to remain the waistline, and only expand the bust apex by the FBA amount.
Don’t have the Karri sewing pattern yet? Get it in store here! We absolutely love seeing what you make, so don’t forget to tag your creations with #MNkarri and @megannielsenpatterns if sharing on social media.
Happy sewing!
[…] Megan Nielsen demonstrates a full bust adjustment on princess seams. […]
Would I need to do a SBA for an A cup? If so…how??!!
[…] How to do a Full Bust Adjustment on princess seams […]
[…] How to do a Full Bust Adjustment on princess seams […]
As you mention, this tutorial leaves you with lots of room added to the waist. As described, it also won’t match up to the waistline of the skirt. I’d love to see the way you actually do your FBA to fix this. I’ve looked at these two tutorials (http://byhandlondon.com/blogs/sew-alongs/11628649-elisalex-dress-sewalong-2-full-bust-adjustment-for-princess-seams-fba and http://www.idlefancy.com/2014/01/sewing-curve-fba-for-princess-seams.html) that address the waist measurement by slanting the side-seam in. Does that affect the grain line? Is that a problem? How is your way different? I think you are saying that you slant it in along the princess line. Cool, this would make sense since you can see right there exactly how much to take out of the waist. Is that better for the grain line? I’m very interested in FBA information, having a rather FB myself. Thanks, Megan, for all your expertise! This pattern is super cute.