Sewing Blog

How to Make a FBA (Full Bust Adjustment) on Princess Seams

To get the best possible fit on your handmade garment, you often have to make some adjustments to the pattern: lengthen or shorten some seams, add a little width to the hips, take the waist seam in…

Making a full bust adjustment on a pattern bodice

One of the most feared, but most efficient, adjustments is the full bust adjustment, “FBA,” along with its twin, the small bust adjustment. Just looking at the diagrams for these fixes might give you a headache. Truth be told, that’s what I thought too before looking at it for real. That’s when I realized that these charts could make sense and weren’t so terrifying after all!

Follow along with this a step-by-step photo tutorial to learn how to make a full bust adjustment on a princess seam, so you too can conquer the adjustment beast!

What is a full bust adjustment?

A full bust adjustment is the most common way to make a bodice sewing pattern larger at the bust. By cutting the pattern pieces and slightly moving them, you can easily add inches to the finished garment.

Before you begin…

Jenny Rushmore measuring bust

Jenny Rushmore in her Full Bust Adjustment for Any Pattern class

If you haven’t already, take your measurements. For this adjustment, the two most essential measurements are your bust and your waist.

Then, it’s a good idea to make a muslin of the bodice for your pattern to know how much you need to increase the bust area. If your bust size is one or two sizes higher than your waist size, you might need a FBA. Another good indication is to look for the cup size on the pattern, as most patterns are designed for a B or C cup.

For a pattern similar to one in the picture above, you would choose your size according to your waist measurements. Let’s say that, for example, your waist is 29″ (size 40) and your bust is 38″ (size 42). The bust measurement for size 40 is 36,” so there is a 2″ difference. You’ll cut the pattern in size 40 and add 1″ (at each bust seam) to make the full bust adjustment — without ever increasing the waistline or the neckline.

Step 1:

drawing lines for full bust adjustment

Cut out your pattern bodice front and side-front pieces. Draw the seam allowances and all the marks (notches, grainline, etc.).

On the bodice side-front piece, draw 3 lines:

  1. A straight line from the waistline to the fullest part of the bust.
  2. A diagonal line from 1/3 of the way up the armhole (remember that the armhole is made of the the front and side-front bodice pieces) to the fullest part of the bust.
  3. A diagonal line from the fullest part of the bust toward the side seam allowance, like a dart.

Step 2:

Cutting lines for full bust adjustment

Place your pattern piece over tracing paper. Cut lines 1 and 2, leaving the armhole seam allowance intact.

Step 3:

Cutting seam allowance for full bust adjustment

Carefully cut the seam allowance, but make sure it’s still attached (see above).

Step 4:

Cut third line for full bust adjustment

Cut line 3, stoping just before you reach the fullest part of the bust. You want the the three pieces to be connected but individually movable.

Step 5:

measuring addition for bust pattern piece

Tape the princess seam to a piece of paper and pivot the pattern along lines 1, 2 and 3, so that the opening at line 1 measures 1″ (or however large your increase needs to be). Make sure the increase is even all the way down line 1. Tape the pattern in place on the paper.

Step 6:

difference in waistlines after bust adjustment

As you can see above, the waistline (bottom edge) on the princess seam piece is not even with the waistline on the side front piece. Draw a line parallel to the waistline on the princess seam part.

Aligning waistline edge on adjustment

Cut along the line. Move the cut piece down until it aligns with the waistline of the side front piece. Make sure it is also aligned with the rightmost edge of the princess seam piece. Tape in place.

Step 7:

Full bust adjustment on pattern paper

With all the pieces taped in place, cut roughly around the new pattern piece.

Step 8:

Draw Line from armhole to princess seam

Draw a line to extend line 3 all the way through princess seam.

Step 9:

cut along drawn line to pivot pattern piece

Cut along line 3 (the horizontal line) from the outer edge until  you reach the fullest part of the bust (line 1).

Step 10:

aligned pattern pieces

Pivot the “dart”  closed, so that the bottom side front piece meets the armhole piece. Tape in place.

Step 11:

adding width to sewing pattern seam allowance

Cut the line 3 from the outside edge of the princess seam to the fullest part of the bust, but don’t cut all the way through. Spread the “dart” open until the bottom edge aligns with the bottom edge of the side front piece. Place a piece of paper under the spread “dart” and tape in place.

Now is a good time to trim away the excess pattern paper around the paper pattern piece.s

Step 12:

adjusted pattern piece

To keep the waistline the original width, we need to remove the width we added to the bust (1″ in this case). Draw a new side seam starting from the rightmost edge of line 3 and ending 1″ from the waistline edge.

Step 13:

Making full bust adjustment on two pattern pieces

Next, you’ll need to add the increases you made to the side front piece to the front piece. Trace 2 lines at the same level you made the two increases on the princess seam pieces. Cut along these lines.

Step 14:

Measuring increase in pattern adjustment

Measure how much you added at each increase on the side-front piece, then add the same measurement to the front piece at the corresponding places. For the bust, measure the seam allowance line, not the cutting line.

Finished pattern pieces for full bust adjustment

There you go: Your new pattern pieces are complete! We have “magically” increased the bust area without touching to the waistline, armhole or neckline.

Full Bust Adjustment Class

Confidently Adjust Any Pattern!

Embrace your shape! Adjust any pattern to fit and flatter your figure with step-by-step guidance from instructor Jenny Rushmore.Get the Class

Editor’s Note: This post was originally published in July 2014 and was updated in March 2018.

23 Comments

Lani Rowell

This makes so much sense explained this way, thank you!

Reply
Sarah Haitch

I tried using this tutorial last night and while I’ve got something that looks like a FBA’d princess seam bodice (I have yet to sew a muslin) there were parts of these steps that weren’t clear at all – garbled sentences, typos, and unclear instructions.
Step 9 has you “Draw a line extending to line 3 of the princess seam.” Which I think should be “Draw a line extending line 3 to the princess seam.”. Now that’s better, but we’ve just cut along line 3 so it’s in two different places and you don’t specify which to use in the text. Then we have to do things in relation to “the fullest point of the bust” which after halfway through stops meaning the point where the fullest point was (which we’ve also cut in half) – if this was labelled as say point A at the start it would be much easier to follow.
There’s also a repeated typo of report for repeat.
It’s a shame that a site whose main function is tutorials could publish something that clearly hasn’t been properly proof read. I don’t mean to blame the original author as it’s very difficult to see your own work through the eyes of a fresh reader.

Reply
Paula White

–> Sarah, please read through the instructions again. They do make sense. You are correct that the word “to” in Step 9 needed to be removed. However, I’m not sure that you understood that the bust point along line 3 is actually a PIVIT POINT. They probably should have explained that part more clearly.

Reply
Sarah Haitch

I tried using this tutorial last night and while I’ve got something that looks like a FBA’d princess seam bodice (I have yet to sew a muslin) there were parts of these steps that weren’t clear at all – garbled sentences, typos, and unclear instructions.
Step 9 has you “Draw a line extending to line 3 of the princess seam.” Which I think should be “Draw a line extending line 3 to the princess seam.”. Now that’s better, but we’ve just cut along line 3 so it’s in two different places and you don’t specify which to use in the text. Then we have to do things in relation to “the fullest point of the bust” which after halfway through stops meaning the point where the fullest point was (which we’ve also cut in half) – if this was labelled as say point A at the start it would be much easier to follow.
There’s also a repeated typo of report for repeat.
It’s a shame that a site whose main function is tutorials could publish something that clearly hasn’t been properly proof read. I don’t mean to blame the original author as it’s very difficult to see your own work through the eyes of a fresh reader.

Reply
Sarah Haitch

I tried using this tutorial last night and while I’ve got something that looks like a FBA’d princess seam bodice (I have yet to sew a muslin) there were parts of these steps that weren’t clear at all – garbled sentences, typos, and unclear instructions.
Step 9 has you “Draw a line extending to line 3 of the princess seam.” Which I think should be “Draw a line extending line 3 to the princess seam.”. Now that’s better, but we’ve just cut along line 3 so it’s in two different places and you don’t specify which to use in the text. Then we have to do things in relation to “the fullest point of the bust” which after halfway through stops meaning the point where the fullest point was (which we’ve also cut in half) – if this was labelled as say point A at the start it would be much easier to follow.
There’s also a repeated typo of report for repeat.
It’s a shame that a site whose main function is tutorials could publish something that clearly hasn’t been properly proof read. I don’t mean to blame the original author as it’s very difficult to see your own work through the eyes of a fresh reader.

Reply
Amy F

Do you have to lengthen the back patterns? To me it seems like the front pieces wouldn’t match up after doing this adjustment, but that may be because I haven’t tried this on hands yet. Any help would be appreciated.

Reply
Paula White

No. You do not readjust the length of the back. Please notice that the front SIDE SEAM remains the same length. But that was a good question.
The front needed to have more width AND length because of the full bust, but the back needed no changes.

Reply
Paula White

I have to disagree with the instructions to select the pattern size by the WAIST measurement and then adjust the bust size. Altering the waist is a relatively easy process. Most important is to select a pattern size that will fit the upper body and shoulders. The whole garment hangs from the shoulders and if the shoulders are not correctly fitted the rest of the garment will not fit right either.
many ladies who have full busts also have even fuller waist-lines, but yet they also need full bust alterations on their patterns.
Patterns should be selected by the upper bust measurement and then the shoulder width and the upper back width need to be checked to see if they are correct. The upper back width is measured at 2/3’s of the way down the armhole, and measured on the body where there is a fold in the skin above the underarm

Reply
Cheryl

I am in complete agreement here. While I did not have a real problem following the directions, I too believe that the pattern size should be chosen based on the upper bust measurement. I have done a few FBA’s on patterns that did not have princess seams and choosing according to the upper bust works !! The shoulders and underarms are always a good fit. My upper bust measurement is 42″ which usually puts me in a size 20 pattern. My full bust measures 48″ and my waist is 41″. If I went with the waist measurement, I’d be cutting a size 24 or 26 which are waaayyyyyyy too big everywhere else ! What I usually do is look at the garment’s finished waist measurements and determine from there whether or not I need to remove or adjust the width I added by doing the FBA.

Reply
Susan Celotto

I have not tried this yet, but I selected a pattern to fit the bust and not the waist (yes, the waist is easier to adjust). However, what I found was that by choosing the pattern size to fit the bust, it caused other fit problems. I needed to take the shoulders up, there was too much bagginess in the garment above the bust next to the sleeve, and the sleeve was set to low (because of the shoulder seams) so that I could not raise my arms higher than shoulder height. I am thinking that choosing the right size of pattern for the rest of the body and just increasing the bust area only will solve all of the other problems that were caused by having a pattern selected by bust size only.

Reply
Emma

Thank you for all the illustrated directions! Now I can make a button down shirt that actually fits. Next to build up the courage to slice into my pattern pieces…

Reply
Susan Celotto

I just discovered Swedish Tracing paper. I was making a wedding dress and needed to make some alterations to the vintage pattern the bride selected. It is very easy to use, you can mark everything with a #2 pencil, and you can even sew it. I have read that you can also use Pellon 830 “easy Pattern,” but neither of the fabric stores near me carries it. I use parchment paper for cooking all of the time, but it didn’t work very well for me when I tried it for pattern making. Swedish Tracing Paper is now my #1 favorite. I copy all of my patterns onto it before cutting so I don’t ruin a pattern by cutting a smaller size from a multiple size pattern (I personally don’t care for the carbon paper & tracing wheel method). Just a thought about something you might try next time you need to alter a pattern.

Reply
fiona

Emma
I never cut an original pattern, trace out onto parchment paper and use the copy, this way you never ruin the original and always have it to go back to.

Reply
JB Camp

This is interesting and looks very doable (in spite of typos and odd phrasing), but I just bought a Vogue pattern that includes individual cup size pieces for the princess bodice up to D. I need to do DD, so I put the D cup piece over the C cup piece and the only difference is the length of the front bodice piece (the same side bodice peices are used for all cup sizes. There is a tiny difference on the other side of the bodice, but not on the curved part where you are showing the changes.

Now I’m confused. It seems that Vogue is simply making the front bodice longer so that there is more to ease into the side bodice piece, thus making a fuller bust. I’m not sure what to do now, but I think I’ll repeat the Vogue enlargement once more for the DD and make a muslin to see how it turns out before I go through all the tracing, slashing, marking, etc.

Reply
Cheryl

Don’t be fooled into thinking those extra pieces are correct ! Just like the original pattern piece, they never are !! Just do your FBA on the average size pattern piece and forget those extra “helps” are even in the envelope !!

Reply
yvonne

I have tried this alteration but by taking the extra width added to the waist off again the side seam is no longer at right angles to the waist seam so when I sew it to the back peice the front centre line drops and angles the waist line downwards along the front of the garment.

Reply
Midori Wilkinson

I think I will have the same issue, and even more accentuated, as I have had to make a 2-inch adjustment and just looking at the angle now it’s pretty out from the 90 that the pattern started out with

Hoping it won’t matter too much in the finished piece, but I am a bit worried now, I have to say!

The mock-up will tell…

Reply
Candice

Hi!

Juste wondering if anyone has tried to do an FBA on the Xeria dress (by Pauline Alice)? It is a princess dress, but with a tiny dart and a front yoke. Looks like a chose a challenge for my first ever FBA! If anyone has any tips!

Reply
Tania Cernezel

Hi, I am hoping you can help me with a bust adjustment for a commercial princess seam pattern. I have read many websites and have found none that cover this fitting issue. My bust is a B cup and my bust, waist and hip circumference match a size 12 commercial pattern identically. My bust apex is higher and closer to the centre of my body than any size 12 pattern I have found. It lands on the centre panel.

How do I adjust for this?

Thank you in advance.

Tania

Reply
CW

Tania,
For bust point that is closer together and higher:
on you–measure the distance between apexes and divide by 2. Let’s call the resulting number “N” for reference.
On paper pattern for darted garments: draw a line “N” inches in from center front parallel to the center front line. Figure out where along that newly drawn line your bus point resides and mark it. Measure the horizontal and vertical distances between your actual bust point and the pattern’s bust point. Then you pick them up and move them and extend. So if your dart is coming from the side, move the dart up the vertical distance and then extend it the horizontal distance.
For princess seam, the “line” is determined by the center front piece and the “fit” is determined by the side front piece. So to move the bust point up, just redraw the side piece so that the fullest point of the piece is higher. If drawing a new curve on your own makes you nervous, you can tape the side seam part of the pattern down, draw a box around the bust area that needs to shift up (don’t draw the box into the armhole–you don’t want to mess with that). Then draw a line perpendicular to the waistline and through the box. Cut the box out. Set a ruler along the vertical line and shif the box up however high you need it to go.
Draw a line to close up the gap in the seamline and cutting lines you created by shifting the box up. In the upper bust area, redraw the upper bust line to a nice slope towards the apex to blend out the jag that was created by the shift.

If you want your princess seam to move closer to center front, you can do this by redrawing the princess seam from the upper bust area all the way down to the waist seam. Once you get past the underbust area you are going to want to keep that redrawn line parallel to the old one otherwise the final seam will look a little weird. Now you are going to transfer all that stuff between the old seamline on the center front piece and the new seamline on the center front piece and transfer it over to the front side piece. Take your scissors and cut that long skinny wedge out and tape the two original princess seamlines together (you will probably need to do little slashes into the skinny piece to make it fit and sit flat. That’s ok.) Redraw your princess seamline on your side front piece so that it is smooth. Draw in your seam allowance. On your center front piece, either redraw your seam allowance line or bring in the existing seam allowance to close up the gap created earlier and tape it down–either way it amounts to the same thing. That’s it.

Reply
Wendy

Why wouldn’t it work to measure that extra inch or whatever needed, but then instead of doing all that complicated cutting and swivelling of the pattern, simply draw freehand a fuller bust line on the pattern, using the original waist, then simply measure the seam line of the new side bust pattern piece, measure the seam line of the original pattern, and subtract that from the length of the new one, then that resulting length is the length you need to add to the middle pattern piece, and I personally would make several cuts at the bust height and spread that extra length between them.

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Marcella A Rich

I have a customer who has a 50″ bust which is 5″ larger than the pattern she bought me (she is a LARGE woman). I measured her bust from the apex to her armcye/side seam which is 9.5″. The pattern in the same place measures 6″. What is the increment used for each inch larger than the pattern ? I’m doing a full-length princess seamed Pirate Coat in an expensive brocade tapestry.

Reply
Liz

This method also adds room at the waist. How do go about removing the extra width at the waist? I’m constantly altering clothing because I need bust and hips but not the extra room in the waist.

Reply

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