Bust Adjustments

In today’s post, we will cover full bust and small bust adjustment. This tutorial is close to my heart (literally), as I have to execute a full bust adjustment on every pattern I make. I like to make this pattern adjustment before sewing my muslin. This allows me to take a more accurate look at any fit issues I might encounter in my mock-up.

DO I NEED A BUST ADJUSTMENT?

Most pattern companies draft patterns based on a B cup. Colette patterns drafted for a C cup for sizes 0-16, and a DD for sizes 18-26.

If you are using a size between 0-16 and have an A or B cup, you will need a small bust adjustment (or SBA). If you have a D cup or larger, you will need a full bust adjustment (or FBA).


For sizes 18-26, if you have a D cup or smaller, you will need a small bust adjustment (or SBA), and if you have a DDD cup or larger, you will need a full bust adjustment (or FBA).

Remember that your sewing cup size can be different than your bra cup size. Commercial sizing—as you know—has become totally convoluted due to vanity sizing. This means that even though you wear a 36DD with one bra brand, you might wear a 34G with another. Luckily, sewing cup sizes are a bit more uniform!

DETERMINE YOUR SEWING CUP SIZE

1) Measure your full bust. This should be around your ribcage and over your bust apex, parallel to the ground.

2) Measure your upper bust. This is the area of your chest right below your underarm.

3) A difference of 1″ means you are an A cup, 2″ is a B cup, 3″ is a C cup, and so on. Again, don’t worry if this is very different from your actual bra cup size!

WHAT SIZE SHOULD I CUT?

Now that you know your sewing cup size, it is time to determine what size to start with.

When you require an FBA or SBA, picking a size isn’t always as straightforward. Here is the technique I like to use:

1) If you are in the 0-16 size range, take your upper bust measurement, then add 3″. This will determine what size you would make if you were a C cup.


2) If you are in the 18-26 size range, add 5 inches to your upper bust measurement. This will determine what size you would make if you were a DD cup.


3) The difference between your actual bust measurement and the size you are cutting is the amount your pattern will need to be adjusted. This is your bust differential measurement.

I know this all can be a bit confusing, so here are some examples:

Example 1


Your upper bust measures at 33″ and your full bust measures at 38″.


33 + 3= 36. This means you would cut a size 6.


38 (your actual bust measurement) – 36 (the pattern bust measurement) = 2 (your bust differential)

Meaning, you would add 2″ to your Sorbetto with an FBA.

Example 2

Your upper bust measures at 41″ and your full bust measures at 44″.


41+5= 46. This means you would cut a size 18.


44 (your actual bust measurement) – 46 (the pattern bust measurement) = -2 (your bust differential)

Meaning, you would subtract 2″ from your Sorbetto with an SBA.

THE PROCESS: FBA

1) Prepare your pattern by tracing the front bodice, transferring all darts, notches, and markings. Also, mark the stitch line at the armscye.

2) Draw a line through the center of the bust dart, extending through the dart point to the bust point (1 1/2″ beyond the dart apex). We will call this line A.

3) Draw a line from the bust point to the hem. This line should be parallel to the grainline. We will call this line B.

4) Draw a third line from the bust point to the armscye sewing line (at roughly the center point). This is line C. You will now have three lines drawn on your pattern.

5) Using your paper shears, cut through line B, starting at the hem. Pivot at the bust point and continue cutting through line C, stopping at the armscye sewing line. Cut a small notch through the seam allowance at line C, leaving a small paper hinge at the stitch line.

6) Next, cut through line A, starting at the side seam, leaving a small paper hinge at the bust point.

7) Now the pattern is slashed and ready to be opened up by the desired amount (bust differential). Divide your bust differential by 2. This is the amount that will need to be added to your pattern piece. On your spare piece of pattern paper, draw two parallel lines that are that distance apart.

8) Very carefully lay your slashed pattern on top of the pattern paper. The hinge that you created at the side dart should allow you to maneuver your B lines so that they lay on your parallel guidelines. Carefully tape down your pattern to your pattern paper, leaving the center front portion free below the lengthen/shorten line.

9) You will notice that the hem of your pattern is now two different lengths. A full bust requires additional length. Use the lengthen/shorten line on the center front to lengthen the center front so that the hem aligns with the side front.

10) Redraw the dart legs by extending the existing dart lines to meet.

11) Finish by trimming away any extra pattern paper and taping as needed.

No additional adjustments need to be made to the rest of the pattern, as only the dart uptake and the center front length have changed.

THE PROCESS: SBA

1) Prepare your pattern by tracing the front bodice, transferring all darts, notches, and markings. Also, mark the sewing line at the armscye.

2) Draw a line through the center of the side dart extending through the dart point to the bust point (1 1/2″ beyond the dart apex) This is line A.

3) Draw a line from the bust point to the hem, parallel to the grainline. This is line B.

4) Draw a third line from the bust point to the center point of the armscye sewing line. This is line C.

5) You now have three lines drawn on your pattern, so you can manipulate the bodice to create less room in the bust. Using your paper shears, cut through line B, starting at the hem. Pivot at the bust point and continue cutting through line C, stopping at the armscye sewing line. Cut a small notch through the seam allowance at line C, leaving a small paper hinge at the sewing line.

6) Next, cut through line A, starting at the side seam, and leaving a small paper hinge at the bust point.

7) Now the pattern is slashed and ready to be minimized at the bust by the desired amount (bust differential). Divide your bust differential by 2. This is the amount that you will need to reduce. Draw a line this distance away and parallel to the center front portion of line B. In this example, I am reducing this pattern by 2″ total, so I have drawn a line 1″ away.

8) Maneuver your pattern so that line B is on your reduction line. Tape line B above the lengthen/shorten line.

9) The center front of your pattern will be longer than the side piece. To even up the hem line, cut along the center front lengthen/shorten line and shorten.

10) Retrace the original dart legs creating a new dart point.

11) Trim the excess dart uptake.

No additional adjustments need to be made to the rest of the pattern, as only the dart uptake and the center front length have changed.

Congratulations! You have conquered bust adjustments. Give yourself a pat on the back and cut yourself a big slice of cake.

NEXT UP…

On Monday we will discuss making a muslin.

Did this lesson help you?

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The Sorbetto Sewalong

  1. Welcome to the Sorbetto Sewalong (25 Comments)
  2. Gather Fabric and Supplies (24 Comments)
  3. Basic Fit Adjustments (17 Comments)
  4. Bust Adjustments (41 Comments)
  5. Making a Muslin (35 Comments)
  6. Shoulder and Sleeve Adjustments (12 Comments)
  7. Front Bodice Adjustments (12 Comments)
  8. Cutting and Prep (2 Comments)
  9. Assemble Bodice (5 Comments)
  10. Sleeves and Bias Finishing (10 Comments)
  11. Hems (11 Comments)
  12. Your Sorbettos! (5 Comments)

Comments

Beth @ Thrifted and Sewn | thriftedandsewn.wordpress.com

How does the sizing from the old Sorbetto version relate to the new Sorbetto version? I’ve been making a size 6 in the old version and quite happy with the fit. According to these measurements, I should make a size 12 with a small bust adjustment and grade down to a size 8 a the hips (I have an inverted triangle, athletic body shape…no waist).
Can’t wait to try the new version but wondering where to start!
Thanks!

Haley Glenn

Hi Beth! I would start with a small bust adjustment on a size 12. I would hold off on grading down in the hips until you make a muslin, as grading down two whole sizes might make it hard to pull over your upper body. Hope this helps!

Emm NLee

Is it worth it to do a small bust adjustment of only .75″? (Following your calculations). That seems very insignificant to me – is it worth it? And if I do it, will I lose space in the waist and hip as well?

Haley Glenn

If this was a more fitted style I would suggest an SBA, but considering the relaxed fit, I think you would be fine skipping it. For pull over garments with no waist darts, bust adjustments do change the waist and hip.This is why I like to sew a muslin after doing bust adjustments it helps you to determine where to add or take away, if needed.

Tanya Gonzalez

Hi. I am confused. I thought one should pick the upper bust measurement for the the cut size so that it will fit the upper chest shoulder area. I am a 33 upper bust and 36 in full bust. If I were to add 3 to the upper bust it would put me in size 6 .. 36 . The bust will fit but the upper chest and shoulder will be too big.

Haley Glenn

Hi Tanya, it sounds like you are a straight size six with a sewing cup size C. I would sew a straight size 6 muslin. I will be covering narrow shoulder adjustments next week which might help!

Tanya Gonzalez

Thank you. I will give it a try .

Laura Cragun

Do you measure your bust with a bra on or without?

Amanda

I had the same question. I thought maybe I should measure while wearing a bra I would typically wear with this top? (Also, I currently nursing so I’m bigger than normal. Oi)

Haley Glenn

I would measure with a bra on if you are planning on wearing one with your finished Sorbetto. This will give you more accurate results.

Lynda

Thanks heaps for the info re determining sewing cup size. According to the pattern size measurements I’m a size 0 so I’ve cut out a muslin that size. I haven’t sewn for about 6mths. I was making a Hayden muslin when the Rue fit issue arose and I lost my just burgeoning garment confidence (plus other blah stuff happening) so I’m keen to finally get back on my sewing ‘horse’ and try out the new blocks. I’ve only made Colette skirts so far. I made a size 4 for the Hayden muslin which fit ok -ish (sleeves bit uncomfortable) so it will be interesting to see how a ‘new’ size 0 goes. I appreciate these tutorials heaps. I don’t think I would have made it through Selene without the photos :)

Lois

I am not getting emails anymore, I have not gotten them for the last two steps but I did get the first two. Do I need to sign up again?

Haley Glenn

Hi Lois, I just double checked on my end and it looks like you are still subscribed. Try checking your spam folder, it might be hiding in there.

Penny

Thank you for this really helpful sewalong. I have a 37″ bust & have made a muslin for version 2 in a size 8, but the bust darts are sitting quite a way below my bust. Does this mean that I need to make a bust adjustment or should I be making a smaller sized garment please? Thank you.

Haley Glenn

Hi Penny, it sounds like you just need to raise the dart. I will be covering that adjustment on Friday so stay tuned!

Penny

Thank you!

Giulia

Hi!!
According to these measurements, I should make a size 4 with a small bust adjustment. But, according to the pattern size measurements I’m a size 0 (I have a 25″ waist and 34″ hips). So, if I pick the size 4, I think the waist and hips will be too big..
What should I do? I’m a bit confused
Thank you!!

Haley Glenn

Hi Giulia, I am happy to help! I would recommend making the 4 with a small bust adjustment. The bust adjustment will also decrease the width in the waist in hips on a pullover garment like Sorbetto.

I really like the explanation about the bust differential and how to helps to determine what size to make and the correction to apply.

I’d like to suggest that any time you make a bust adjustment you should fold out the dart and re-draw the side seam. That folded dart intake will not automatically be the correct length if you snip it off as in this tutorial.

Renee

Hi, the first step says to prepare the bodice by tracing the pattern and transferring all markings. Tracing the pattern and transferring to what? It looks like the photos are just using the printed pattern. Thanks!

Haley Glenn

Hi Renee, I can see how that could cause confusion, to be more clear I should have used a traced pattern in the images. I recommend tracing the pattern because it is a good habit to have. Anytime I am making a big change to a pattern—like a small or full bust adjustment—I like to keep my original pattern intact just in case I decide after a muslin to try a different alteration. You can use pattern paper, trace paper, or any other paper you have on hand to do this.

Stephanie

this is why I like the digital patterns. If I mess up I can print it again without having to buy it again, when I inevitably mess up.

Renee

One more, step 10. Can you elaborate? I tried placing my traced piece over the original pattern and retraced the original dart lines but it seemed way off my new dart. Looking at your photo, it looks like you just snip off the overlaps tips and the new point is where they intersect at the new bust point. How does the original dart come into play? Thanks!

Haley Glenn

Hi Renee, I am happy to help. When executing a small bust adjustment your dart will become narrower and shorter. On your altered pattern piece, the two dart legs are correct, they simply intersect at a new point. Additionally, you may now have a paper “flap” obscuring the lower dart leg. This step is telling you to redraw this line so it is more visible. Once the dart legs are drawn, you can fold out the dart and true the side seam at the dart.

I’m really confused about what size to cut. Upper bust 40″, full bust 42″, waist 36″. I have somewhat narrow shoulders. I forget what my hips are, LOL, but they are about my bust (large belly, no butt!). I seem to have shrunk my bust somehow since the last time I did my measurements, but I take a 36DD bra usually. Help!

Stephanie

I’m in the same boat. My measurements are close to yours in preparation, but I’m a bit bigger. I decided to cut an 18 so I might not have to do a FBA this time. I think you would be more like a 14 right? You will probably still have to do an FBA.

Haley Glenn

Hi Tracy, I am happy to help! I would recommend a size 16 with a 2″ SBA. This should give you a good fit in the bust and the waist.

Hi, I have made the SBA adjustment and that’s worked fine for me but when I try to baste my sleeve onto my top, the sleeve is far bigger than the armhole. I am not sure what I have done wrong or how to make it fit. Any idea why there is an issue, I have at least an extra inch on the sleeve…

Haley Glenn

That is puzzling. The only case I could think of that would reduce the armscye, is if you slashed through instead of to the armscye stitch line in step 5. Otherwise, this could be a result of your fabric stretching.

Emily

I need a FBA of 1″ as well as to move the bust dart up (about 1.5″). Which adjustment do I do first?

Haley Glenn

Hi Emily, I recommend moving the dart after the FBA.

Nicole

I just found the sew a long after making a muslin for Sorbetto. I did a SBA on a size 8 (34 upper bust, 29 waist, and 39 hip) reducing .75 for a total 1.5″ reduction. After making the muslin, the point of the dart was an inch below by bust apex. Fit was pretty good besides the dart issue. What fit do I need to adjust the dart up an inch?

Haley Glenn

Hi Nicole, I am happy to help. I covered moving the dart in this sewalong post. Hope that helps!

Sona

what do the pull lines from the bust apex diagonal to bottom side hem mean?

[…] Small Bust Adjustment. Tutorials for bust adjustments abound online, but I went ahead and used the one offered by Colette on the Sewalongs […]

Claudia

Hello, I finished my first muslin last night and realized I need to do a SBA and move the dart up. But I have a question about the length of the front piece. You said after doing the SBA we will have a front piece with a longer center part, so we need to shorten that part to make it match the side part. However, if we are happy with the length of the top, can we make the side part match the center length instead? or will that mess up the pattern? The Sorbetto is my second sewing project so this might me a stupid question :)…. Also, do we need to modified anything on the back piece?
Thank you so much!

Haley Glenn

Hi Claudia, you can definitely lengthen at the side instead. Just make sure you lengthen the back bodice to match.

Claudia

Thank you Haley!

Johanna van der Heul

Hello, I am following this sewalong at the moment. I hope you will still have time to answer my questions. My upper bust is 91 cm and my full bust is 94 cm. I had to make a SBA of 4,5 cm :2 = 2,25 cm following your instructions. I managed to do this but you mention nothing has changed on the pattern regarding the width. But my front pattern piece is 2,25 cm more narrow now. Which is logical because I had to move line B for 2,25 cm? Where did it go wrong? Another question: I chose size 10 and I decided to make a muslin without changes to see how that would be. The size is quite good, the only thing is that the bust dartpoint is 2,5 cm too low. I raised the dartpoint and now it looks good. I want to make a second muslin with the SBA to see the difference and to experience to make a SBA. Please can you help me? Thank you.

Haley Glenn

Hi Joana! It sounds like you have followed instructions correctly. The width of your front pattern piece does change with an SBA on pullover-style tops. This is completely normal. The measurement that stays the same is the side seam and armscye length, meaning you don’t have to alter your back pattern piece or your sleeve. Hope this helps!

Johanna

Hello Haley,
Thank you very much for your help. I did the SBA and I raised the bustdart. I made another muslin and I saw I had to shorten the bustdart. The dartpoint was on the bustpoint. I shortened the dart with 1,5″, made another muslin and whoopee, it is a very nice fit now. Worth the effort. Thanks again!

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