The Ultimate Guide to a Full Bust Adjustment

Bodies come in all shapes and sizes, and if you’re larger busted, chances are you’ll need to become acquainted with an important fitting improvement: the Full Bust Adjustment. Otherwise known as an FBA, this adjustment will allow you to add any additional length and width you may need in the bust area and is really key to getting a beautiful fit for full chests. In this blog post, we will walk you through how to do an FBA in just about every conceivable type of bodice. It's an exhaustive guide to an alteration that a lot of people struggle with – let's dig in!

Cup Sizing and Full Bust Adjustments

Before we get started, make sure you have identified your unique bust point on the pattern, and that all bust darts are pointing toward your apex; you can learn how to do this in our blog post Understanding Where Darts Should Point.

Next, it’s important to understand how cup sizing works for patternmaking since cup sizing determines whether or not you need an FBA. In drafting terms, cup sizing does NOT refer to bra sizing (bra sizing uses a different system altogether, so please don’t assume your cup size is connected to cup sizing for patterns!)

In pattern drafting, cup sizing is based on the difference in inches between your high bust and full bust. In other words, it’s a comparison between your upper chest and the fullest part of your breasts. Every inch difference equals a cup size (1” difference = A cup, 2” difference = B cup, 3” difference = C cup…).

Because pattern companies often share the cup size that they draft for, you can calculate the difference between your upper and full bust measurements and compare it to the pattern. Here are the cup sizes for our brands:

• The CCP 0-20 size range is drafted for a B cup, with a 2” difference between high and full bust.
• The CCP 14-32 size range is drafted for a D cup, with a 4” difference between full and high bust. Here is the CCP size chart.
• The Deer&Doe 34-48 range is drafted for a B cup with a 2" difference between high and full bust.
• The Deer&Doe 46-60 range is drafted for a D cup, with a 4” difference between high and full bust. See the D&D size charts here.

If you have a smaller or a larger cup size than what is drafted, you may want to adjust the pattern with a Small Bust Adjustment (SBA) or a Full Bust Adjustment (FBA) to account for the volume difference. We will discuss Small bust adjustments in an upcoming blog post – for now, we’ll focus on the FBA.

How Much of an FBA Do I Need?

To figure out how big of an alteration you need to make before cutting your fabric, follow these steps:

1. Determine your cup size by calculating the difference between your high bust and full bust. Each inch equals a cup size. If you are a C cup or higher (3” +) in our 0-20 range, or an E cup or higher (5” +) in our 14-32 range, congrats! You could use an FBA.
   
2. Next, choose your pattern size based on the corresponding high bust measurement for that size. The high bust measurement is often found in the pattern size chart, but if it isn’t you can do the following calculation IF you know the cup size:
   
   High bust measurement = Full Bust measurement - Cup size amount (2" for B cup, 3" for C cup, 4" for D cup etc.)
   
3. Now, compare the full bust measurement of the size you selected to your own full bust measurement.
   
   Total Full Bust Adjustment = My Full Bust Measurement - Full Bust Measurement of the Pattern
   
   For example, let’s say you have a 44” high bust and a 50” full bust and want to cut a size from our 14-32 size range. You have a 6” difference between full and high bust, which is 2” more than the D cup we draft for. You will choose a size 20 (which also has a 44” high bust). The full bust measurement for that size is 48” - you will therefore need to make a 2” total FBA to the pattern to get to the 50" you need.
   
4. Divide that difference in two to get the amount your bodice will need to be adjusted (remember: we are only adjusting half the bodice, so the total amount in inches will actually be doubled once you cut our your complete bodice!). Let’s call this number the “Half FBA”.
   
   Half FBA = Total Full Bust Adjustment / 2.
   
   Using the example above, you will need to make a 1" (25 mm) Half FBA.

To figure out the size of your adjustment from your muslin, slash from the armhole to the center front line crossing the apex, and down through the center front line if more width at the waist is required. Measure the extension required along each cut.

Wait - Why am I choosing a size based on my High Bust?

Choosing a base size following your high bust ensures that you choose a size that will fit your upper chest, which means that the neck and the shoulders will be in proportion to your upper body. The FBA will take care of creating enough room around the full bust.

If you just chose a pattern size based on your full bust measurement, you might find that you have enough room through the bust but have excess fabric around the upper chest and shoulders. Symptoms of this are gaping fabric at the front armhole and too wide shoulders.  It feels counter-intuitive, but trust us - for big busts, the high bust measurement is the way to go when it comes to choosing a size!

What symptoms indicate I need an FBA?

It’s pretty easy to tell when you need an FBA. If you’ve made a muslin without doing this adjustment first, or haven’t done a large enough FBA, you’ll notice the following symptoms. All indicate that you don’t have enough circumference or length around and through the bust.

• Tightness around the bust. 
• Horizontal wrinkles form between the breasts. 
• Diagonal wrinkles appear from under the arm towards the bust. 
• Excess gaping fabric at the front armhole. 
• The front waistline and hem hang higher than the back. 
• The side seam bows towards the front. 

Fortunately, it is possible to fix these fitting issues with a Full Bust Adjustment! Let’s dig into this adjustment for different types of bodices. As you read through, you’ll see that the common denominator in all adjustments is that the lower section of the armscye is usually rotated to create room for the bust.

Full Bust Adjustment for a One Dart Bodice

This alteration will work regardless of the position of the dart. Here we will show you how to do the same adjustment for both waist and bust darts.

Bust Dart FBA

Waist Dart FBA

1. Draw the following lines on the front piece. L1 - Starting one third of the way along the armhole, through the apex and across to center front. L2 - From the center of the dart legs to the apex.
   
2. Cut along L1 to the armhole (leaving a small paper hinge at armhole) and along L2 to the apex (leaving a hinge at the apex). Spread the center lower piece to add length and width until the center front lines are parallel the same distance apart as the “Half FBA” (ie. following the example above, the two center front lines will be 1" apart). The lower side piece will rotate accordingly.
   
3. Reorient the dart towards the original apex and lengthen or shorten the dart as needed so the point is 1”-2” from your bust apex. The width of the dart will be increased – if it becomes too wide, consider dividing it. True the dart, the center front, and the armscye.
   
4. Optional: The alteration above increases the front waist measurement, which means adjusting any connecting pieces like a skirt or pants. If you prefer to keep the front waist measurement as drafted, we recommend you do the following:
   • Draw a new line on the front piece from the point where the armhole joins the side seam down to the waist, approx 2” from the side seam.
   • Cut along this line, leaving a hinge at the armscye, and rotate the side piece towards the center front until the waist measurement is the same as originally drafted. True the underarm dart if there was one, and true the waist seam.

FBA for a Multiple-darted Bodice

If the bodice you are working with has multiple darts we recommend you follow the instructions above. You will still be drawing L1 through the bottom third of the armscye; ignore the bust dart for the time being and add the needed width to the center front as outlined above.

Next, reorient all darts towards the apex and reduce the spread of the new wider dart by transferring the excess to the second dart.  To distribute the width between two darts, cut through the center of both darts and pivot the sections at the apex to distribute the spread. Lengthen or shorten the dart as needed so the point is 1”-2” from your bust apex”, and true the darts as shown below.

FBA for a Bodice Without Darts

There are a few ways to add volume around the bust in a bodice without darts, and the way you choose to do this might depend on the type of fabric you are using.

How to Add a Dart

This alteration is generally for woven patterns, but it works for knits as well. See the following alteration to add an FBA to knits without a dart.

Start by marking your bust apex on the pattern.

1. Draw the following lines on the front piece: L1 - Starting one third of the way along the armhole, through the apex and across to center front. L2 - From the apex to the seam where you want the dart to end (in this case, along the side seam).
2. Cut along L1 to the armhole and along L2 to the apex, leaving paper hinges. Spread the center lower piece to add length and width until the center fronts are parallel and matching the “Half FBA” measurment. The lower side piece will rotate as L2 opens to create a dart. 
3. Reorient the dart towards the original apex and lengthen or shorten the dart as needed so the point is 1”-2” from your bust apex. True the dart, the center front, and the armscye.
4. Optional: The alteration above increases the front waist measurement, which means adjusting any connecting pieces like a skirt or pants. If you prefer to keep the front waist measurement as drafted, we recommend you do the following:
   • Draw a new line on the front piece from the point where the armhole joins the side seam down to the waist, approx 2” from the side seam.
   • Cut along this line, leaving a hinge at the armscye, and rotate the side piece towards the center front until the waist measurement is the same as originally drafted. True the underarm dart if there was one, and true the waist seam.

How to Ease the Dart Into the Side Seam

If you are working with a pattern recommended for knits and prefer not to add a dart, you can also gather the dart spread along the side seam around the dart location so the excess room is built into the side seam. This alteration works best for darts no wider than 2”.

1. Draw the following lines on the front piece: L1 - Starting one third of the way along the armhole, through the apex and across to center front. L2 - From the apex to the seam where you want the dart to end (in this case, along the side seam).
2. Cut along L1 to the armhole and along L2 to the apex, leaving paper hinges. Spread the center lower piece to add length and width until the center fronts are parallel and matching the “Half FBA” measurment. The lower side piece will rotate as L2 opens to create a dart. 
3. Measure the dart spread at the base, and add a notch the same distance above the upper dart leg, and another notch below the lower dart leg. 
4. Transfer the notches onto the back side seam. 
5. On the back piece, the distance between the notches should be 2X the dart spread, and on the front piece the distance between the notches should be 3X the dart spread. True the side seams. When sewing, the front piece will be gathered between the notches, and eased onto the notches on the back side seam.
6. Optional: This alteration increases the front waist measurement, which means adjusting any connecting pieces like a skirt or pants. If you prefer to keep the front waist measurement as drafted, we recommend you do the following:
   • Draw a new line on the front piece from the point where the armhole joins the side seam down to cross the hem 2” from the side seam. 
   • Cut along this line, leaving a hinge at the armscye, and rotate the side piece towards the center front until the waist measurement is the same as originally drafted. True the waist seam or hem.

FBA With Pleats or Gathers

There are a few ways to add volume around the bust in a bodice with gathers or pleats. One of them involves adding a dart, and the other one distributes the volume into the gathers and pleats. Let’s take a look!

How to Create a Dart When There are Pleats or Gathers

If you are working with a gathered or pleated bodice, this method will create a dart that is not integrated into the gathered/pleated section. Find the instructions below the diagrams.

Pleats

Gathers

For a bodice where the gathering happens along the waist seam.

1. Draw the following lines on the front piece: L1 - Starting one third of the way along the armhole, through the apex and across to center front. L2 - From the apex to the side seam.
2. Cut along L1 to the armhole and along L2 to the apex, leaving paper hinges. Spread the center lower piece to add length and width until the center fronts are parallel and matching the “Half FBA” measurment. The lower side piece will rotate as L2 opens to create a dart. 
3. Reorient the dart towards the original apex position. True the dart, the center front, and the armscye.
4. Optional: This alteration increases the front waist measurement, which means adjusting any connecting pieces like a skirt or pants. If the width can't be added to the gathering (ie. along a waist seam) and you prefer to keep the front waist measurement as drafted, we recommend you do the following:
   • Draw a new line on the front piece from the point where the armhole joins the side seam down to cross the waist 2” from the side seam. 
   • Cut along this line, leaving a hinge at the armscye, and rotate the side piece towards the center front until the waist measurement is the same as originally drafted. True the underarm dart if there was one, and the waist seam.

How to Integrate New Volume Within Pleats

If you are working with a pleated bodice, this method will integrate width into the pleats.

1. Draw the following lines on the front piece: L1 - Starting one third of the way along the armhole, through the apex and across to center front. L2 + L3 - From the apex through the center of each pleat. 
2. Cut along L1 to the armhole and along L2+L3 to the apex. Spread the center piece down to add length and width until the center fronts are parallel and matching the “Half FBA” measurement. The lower side pieces will rotate as L2+L3 open to widen the pleats. Divide the spread equally between both pleats. 
3. Reorient the pleats towards the original apex position. True the pleats, the center front, and the armscye.
4. Optional: This alteration increases the front waist measurement, which means adjusting any connecting pieces like a skirt or pants. If you prefer to keep the front waist measurement as drafted, we recommend you do the following:
   • Draw a new line on the front piece from the point where the armhole joins the side seam down to cross the waist 2” from the side seam. 
   • Cut along this line, leaving a hinge at the armscye, and rotate the side piece towards the center front until the waist measurement is the same as originally drafted. True the waist seam.

How to Integrate New Volume Within Gathers

If you are working with a gathered bodice, this method will increase the density of the gathers in the gathering section. In this example, we are adding width through a gathered shoulder.

1. Draw the following lines on the front piece: L1 - Starting one third of the way along the armhole, through the apex and across to center front. L2 + L3 - From the apex to the gathering section at two points.
2. Cut along L1 to the armhole and along L2+L3 to the apex. Spread the center piece down to add length and width until the center fronts are parallel and matching the “Half FBA” measurement. The other sections will rotate as L2+L3 open to increase the gathering section.
3. True the seam with the gathers, the center front, and the armscye.
4. Optional: This alteration increases the front waist measurement, which means adjusting any connecting pieces like a skirt or pants. If you prefer to keep the front waist measurement as drafted, we recommend you do the following:
   • Draw a new line on the front piece from the point where the armhole joins the side seam down to cross the waist 2” from the side seam. 
   • Cut along this line, leaving a hinge at the armscye, and rotate the side piece towards the center front until the waist measurement is the same as originally drafted. True the waist seam.

FBA for a Raglan Bodice

1. Draw the following lines on the front piece: L1 - Starting one third of the way along the armhole, through the apex and across to center front. L2 - From the apex to the seam where you want the dart to end.
2. Cut along L1 to the armscye and along L2 to the apex. Spread the center piece down to add length and width until the center fronts are parallel and matching the “Half FBA” measurement. The lower side piece will rotate as L2 opens to create a dart. 
3. Reorient the dart towards the original apex position. True the dart, the center front, and the armscye.
4. Optional: This alteration increases the front waist measurement, which means adjusting any connecting pieces like a skirt or pants. If you prefer to keep the front waist measurement as drafted, we recommend you do the following:
   • Draw a new line on the front piece from the point where the armhole joins the side seam down to cross the waist 2” from the side seam. 
   • Cut along this line, leaving a hinge at the armscye, and rotate the side piece towards the center front until the waist measurement is the same as originally drafted. True the underarm dart if there was one, and true the waist seam.

Full Bust Adjustment for Princess Seams

I’ve been telling you all along how princess seams are super easy to fit, and yet, when it comes to FBAs you will find multiple and seemingly complex variations on how to do this alteration in a princess seamed bodice. Because my brain likes structure, I’m going to share with you the way I prefer to do this alteration. You will see that it’s very similar to what we have done for many of the bodices we have discussed so far.

This alteration assumes that your apex coincides with the pattern apex, in other words, the shoulder to apex measurement on the pattern is the same as your body, and that at the apex, the horizontal width of the center piece is equal to your apex to apex measurement without the seam allowances. Let’s get into how to do this alteration!

The diagrams show a shoulder princess seam and an armscye princess seam, but the same principles apply to other types of princess seams we have discussed. Find the instructions below the diagrams.

Shoulder Princess Seam

Armscye Princess Seam

1. Draw the stitch line of the princess seam in both center and side front pieces, and ensure the apex is clearly marked on the seam line of each piece. On the side front piece draw L1 from one-third of the way up the armhole to the center front across the apex. If you have an armscye princess seam, draw L1 from two thirds of the way up from the bottom of the armscye to the apex. Draw L2 from the apex to the side seam, and L3 from the apex to the waist. On the center front piece draw L4 Horizontally ~1”  above the waist seam.
2. On the side front piece: Cut L3 from the waist to the apex, but not past the seam allowance, and through L1 from the apex to the armscye. Cut L2 from the side seam to the apex. Spread the lower side section until L3 separates into two parallel lines at a distance of the“Half FBA” measurement. The upper side piece will rotate as L2 opens to create a dart. 
3. On the side front piece: Reorient the dart point towards the apex by drawing  the legs of the dart connecting the base of the dart with the apex. Extend the princess seam and the waist seam down so they meet perpendicularly. Measure the extension along the princess seam. 
4. Cut one of the dart legs to the apex, and through the princess seam allowance. Close the dart and fill out that tiny clip in the seam allowance. True the side seam. 
5. Trace a new grainline joining the tips of the previous grainline. True the waist seam and the princess seam. 
6. Center front piece:
   • Cut through L4 and spread the upper and lower sections by the amount you extended the princess seam on the side piece. 
   • Draw a smooth curve joining the two sections, and true the princess seam between the center and side pieces.
7. Optional: This alteration increases the front waist measurement, which means adjusting any connecting pieces like a skirt or pants. If you prefer to keep the front waist measurement as drafted, we recommend you do the following:
   • Draw a new line on the side front piece from the point where the armhole joins the side seam down to cross the waist 2” from the side seam. 
   • Cut along this line, leaving a hinge at the armscye, and rotate the side piece towards the front until the waist measurement is the same as originally drafted. True the underarm dart if there was one, and true the waist seam.

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Many tiny pattern pieces were cut and much reflection went into writing this blog post. My takeaway is that darts are magical 💫!! Regardless of whether you are doing an FBA with our patterns or not, save this blog post for future reference.

And remember that if you are working with one of our patterns, chances are that we have an alteration blog post for it on the CCP or DD blogs – just search posts by pattern to see what applicable blog posts there are. You got this!