Tutorial: How to do a full bust adjustment (FBA) on a dartless pattern

I’m going to be “bringing home” a few of the tutorials that I did over on the Sew the Show blog.  Becca and I have discussed a lot and decided to shut down the STS blog in the near future.  Don’t worry, Sew the Show will still be around, just in the Facebook group, and housed on our individual blogs.  The pressure of trying to maintain yet another blog was getting to be too much for both of us, and it just seemed superfluous.  But these tutorials took me a long time, so I wasn’t about to just let them disappear into cyberspace!


Creative Counselor: How to do an FBA on a dartless pattern

Well, I gave it a good college try, but I just couldn’t get in to The Walking Dead.  But even though not every theme show is fitted to everyone (me included), I still knew there were elements of TWD fashion that I could easily incorporate into my own closet. 

Exhibit A: the flannel shirt.

Creative Counselor: How to do an FBA on a dartless pattern

I’ve had a hankering lately to break out my Grainline Archer pattern and have another go at it.  I made a chambray one last summer and for some reason I just never wore it.  I’ve never been a big button-down person, though I am coming around to them.  And my chambray Archer always felt strangely bulky to me.

Creative Counselor: How to do an FBA on a dartless pattern
See all the extra fabric under my arm? And the shoulder seam sits farther down my shoulder than it’s supposed to.

When I posted this photo on Facebook, Becca commented that it might be a tad too big.  The extra fabric under the arms in the size 6 I made would tend to make the whole shirt feel bulky.  I started looking more closely at it and I realized that there was a lot of fabric under the arms and the shoulder seams were a little too far down on my shoulder.  I went back and looked at the pattern measurements and realized that my measurements actually put me in a size 4 rather than a size 6 and I would need a small full bust adjustment.  (If you’re interested in how I puzzled that out from measurements, check out my earlier post about choosing your size).

I muslined the size 4, and as you can see, I was right — the shoulder seam was in a much better place but I did need an FBA.  If my measurements hadn’t made me pretty positive that I needed the FBA, the funny wrinkling around the bust and armcyce certain did.

Creative Counselor: How to do an FBA on a dartless pattern
You can see all kinds of wrinkling around the arm and bust. The telltale sign for me was that I couldn’t get a good idea of what other changes I needed to make without more room in the bust area.

The only challenge I saw was that the Archer doesn’t have a bust dart and most FBA tutorials I’ve seen are written for patterns with a bust dart. Well, I’m here to remedy that.

Down to business!  This tutorial will work for dartless and darted patterns and both woven and knit, though I’m working off the dartless woven Archer.  If you’re using a darted pattern, your process is a little shorter so you’re getting off easy!

Step 1:  Determine the size of your FBA.

Huh?  What does that mean, the “size” of the FBA?

That means figure out how much room you need to add to the front of your garment.  In my case, the size 4 Archer measurement is for a 34″ full bust, and my full bust is 35″.  That means I need to add a total of 1 inch to the pattern.  Since I’ll cut two front bodice pieces, I need to add 0.5″ to my pattern piece.

Step 2: Find your bust apex.

If you’re using a woven pattern, like the Archer, you can probably find the apex of your bust from the pattern piece.  That’s what I did.  I just put the pattern piece up to my body and marked my bust apex. If you’re using a knit pattern, you’ll probably need to sew a muslin and mark it while on your body.  Because knit fabric stretches, the bust apex will be in a different place than it will be on a woven pattern.

Step 3: Draw your lines.

Pull out the markers!  To do your FBA, you’re going to need to draw 4 different lines, as indicated below:

Creative Counselor: How to do an FBA on a dartless pattern

In the photo above, the black dot is my bust apex.  From the bust apex, first draw a vertical line from the bust apex straight to the hem (the green line).

Next draw a line from the bust apex to the side seam (the blue line).  If you’re using a darted pattern, draw this line straight down the middle of the dart.

Third, draw a line from the bust apex to the armcycle (the red line).

Finally, draw a line from the green line to the center front of the pattern piece (the orange line).  This line can be anywhere along the green line — it really doesn’t matter.

Step 4: Cut and spread.

Creative Counselor: How to do an FBA on a dartless pattern

Now that your lines are drawn, it’s time to cut!

  1. First, cut straight up the green line to the bust apex.
  2. Second, cut along the red line right up to the armcyce, but DO NOT CUT the armcyce.  Leave a tiny amount of paper there joining the armcyce.
  3. Third, cut along the blue line from the side seam right up to the bust apex, but DO NOT CUT all the way through the apex.  Again, leave a tiny amount of paper joining the two pieces.
  4. Finally, cut along the orange line.

Spread the pattern piece the necessary amount.  In the image above, I spread the pattern piece out so that there is an extra 0.5″ inches at the dot marking my bust apex.

Line up the rest of the pieces.  You can see in the photo how the other lines change when I added that extra width in the bust.

Step 5: Fill in with paper.

Now this is where most FBA tutorials stop, even though they really should include the next step, regardless of whether the pattern has a dart.

Creative Counselor: How to do an FBA on a dartless pattern

Step 6:  Adjust the waist circumference.

When you slashed and spread the pattern piece, you added width all the way down, including to the waist and hip.  We needed more width in the bust, not the waist and hip, so now we need to remove that width.

To do that, first figure out where your waist falls on the pattern piece.  To find that, I found my natural waist (side bend and where your torso bends is your natural waist), and measured the distance from that point to my underarm.  The X in the photo marks that point.

In my FBA, I added 0.5″ to the pattern piece, which added that same amount of width all the way down.

From the waist point on your pattern, measure the amount of width you need to remove (here, 0.5″).  Mark that point and draw a straight line from that point to the bottom of the dart that you created by slashing and spreading the pattern.

Continue the line down to the hemline, removing the extra width from the waist through the hip and to the hem.

Trim off the excess.

Creative Counselor: How to do an FBA on a dartless pattern

If you’re using a darted pattern, this is your last step!  You’re done — continue with fitting or sewing, as necessary.

Step 7: Adjust the side seam.

Now that we’ve removed the extra width in the waist and hip, we also need to remove the extra length from the side seam.

If you’re using a darted pattern, this step isn’t necessary.  The extra length is in the bust dart, and it will disappear as soon as you sew the dart.  Without a bust dart, we need to adjust the pattern piece to remove that length from the side seam.

Creative Counselor: How to do an FBA on a dartless pattern

Keep in mind that you’re only removing the width from the side seam.  You actually want to keep the extra length in front — you need it so that the bodice covers the girls and has a straight line at the waist.

To true up my side seam, I took my original Archer pattern piece, laid it on top of my modified piece to determine the correct length of the side seam, and the retraced the hemline to remove the excess from the side seam.

Voila! You’re done!

Congratulations!  You have now successfully added width to the bust of your pattern while leaving the waist and hip measurements unchanged.

Take a look and see how my modified pattern piece differs from the original:

Creative Counselor: How to do an FBA on a dartless pattern
You can see that I have about 0.5″ of extra width in the bust, which will total 1″ when the bodice is sewn together. The armscyce has altered slightly to account for the larger bust width, though the circumference of the armscyce is unchanged. There’s also extra length in the center front to help cover the bust.

But wait, there’s more!

The Archer shirt has a front button placket, so don’t forget to modify that as well!

Creative Counselor: How to do an FBA on a dartless pattern

My FBA added an extra 0.5″ of length to the main bodice pattern piece, so I need to add that same amount to my button placket, otherwise it won’t fit when I go to attach it.

Alright, FBA is done, so it’s the moment of truth.  Muslin #2:

Creative Counselor: How to do an FBA on a dartless pattern

Success!  I still have funny wrinkling in the armscyce area, but there is enough width in the bust now!  Those armcyce wrinkles are typical for me, and will be the subject of my next Archer week post — the sloping shoulder adjustment.  Stay tuned!

Ultimately, I ended up with a really comfortable and well-fitting shirt, and the FBA was the first piece in the puzzle.

Creative Counselor: How to do an FBA on a dartless pattern

0 thoughts on “Tutorial: How to do a full bust adjustment (FBA) on a dartless pattern

  1. This post is full of so much useful information. I’m constantly directing people here when they need guidance regarding FBAs.

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