How to make a full bust adjustment to a sewing pattern

A full bust adjustment to a sewing pattern is simple and easy to do when you require extra room without adding space at the shoulders and armhole.  It is without a doubt the most requested tutorial I have ever gotten.

full bust adjustmentTo be honest with you, I could write a whole book about this, but there are some very good ones out there that are already.  Unfortunately, none of them will answer all your questions.  The reason is that altering a pattern for a better fit depends on your measurements and the style of the pattern.

I will not go into more details, the argument can last many weeks, so it makes the perfect topic for another article.

Before we get started, I think it is important to mention that this is an intermediate to advanced sewing technique.  It's probably not something you want to try on your first garment project. But if you're already comfortable with garment sewing and want to move your sewing skills up to the next level where you can really start to customize patterns to fit perfectly, please read on!

full bust adjustment

Getting started

There are generally considered to be three types of pattern alteration which are listed below:

Where we take a pin and move the patter as a pendulum to increase or decrease it in size without changing the armhole size, normally used when more than one alteration needs to be done, for example, enlarge the bust, waist, and hips without making the shoulder wider.
Where we use darts and specific measurement point to cut the pattern to change it to your measurements.  Use only if you are increasing the size up to two inches.  This is not the first time I talk about this, I have mentioned this rule on the walking shorts sew-along.  It is possible to alter the pattern further than inches but be aware that a bigger amount will result in an increment of the armhole and a change in the shoulder slope.
This is also known as the Advanced Method made on muslin where multiple alterations are necessary.

I'm going to be using our recent pattern and tutorial featuring the Proteus Cardigan Pattern for Many Occasions to demonstrate this technique.  It will form part of the sew-along we're going using this pattern.  However, you can use this pattern on other patterns as well.

cardigan pattern

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Materials for making a full bust adjustment:

  • pattern making paper
  • ruler
  • grading ruler
  • 2B pencil
  • tape measure
  • sticky tape
  • pin or awl

How to make a full bust adjustment

I will show you how to make a full bust adjustment by the Slash and Slide Method, and a combination of the Pivot and Slide Method.   I will not be showing you how to use the Seam Method because that is better demonstrated on a video with a life model.  We'll cover that one at a later time.

full bust adjustment

Step One:  Measure yourself

Use the drawing below to write your measurements.  This FREE template for a full bust alteration can be downloaded from our sister site Sew4Free.  Please remember to join the mailing list while you're over there to get a new list of FREE sewing patterns every Saturday.  That's all we ask!

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Download the Free Template

You can download this Handy Measurement Template from our sister site at Sewing4free.com.

All we ask is that you join our FREE mailing list if you would like to get this template.

For help downloading and printing PDF patterns, please CLICK HERE.

Once you have measured yourself, take the bust measurement and print the pattern closest to your size but towards the smaller size.

Here are the finished measurements of the Proteus Cardigan Pattern.

S M L XL 2XL
Bust 33″ 37″ 41″ 44″ 48″
Waist 39″ 43″ 47″ 51″ 55″
Hem Width 63″ 67″ 71″ 73″ 77″

Step Two: Choose the pattern you will alter

Here are the patterns you can use today, they are free and available on our site with a step-by-step tutorial.

Increasing a pattern without a dart:

Increasing a pattern with a dart:

Making a full bust adjustment is easier when the pattern already has a dart.  For this technique, you can use the following patterns.

Step Three:  How to choose the right size pattern

You will need the Chest (2) Bust (3) and Under Bust measurements (4) to determine what method you will use.  Write your measurements in the spaces provided.

Step Four:  How to choose the right method

As a rule, it is better to use a smaller size than to try to make something smaller from a bigger size.  This is at a pattern level, of course.  The reason has to do with the shoulder length and the armscye length.

If you only require the bust alteration you can use the Slash and Slide Method.

If your measurements are 2″ to 6″ different and you require multiple adjustments, use the Pivot and Slide Method.

Full Bust adjustment using the Slash and Slide Method

For those with a dart who only need to increase by 2″ or less:

  1.  Trace the pattern on a large piece of pattern making paper.  Tape the front line to the pattern paper.
  2.   Located the center of the dart and trace a horizontal line in the middle of the dart to the apex of the bust. (refer to your chart)
  3.   Trace a line from the apex to the shoulder roughly in the middle of your shoulder.
  4.   From the point of the dart trace a straight line to the hem.
  5.   Cut from the hem to the apex to the shoulder but not though, (do not cut the pattern in two)full bust adjustment
  6. Spread the pattern by half of the measurement you need.full bust adjustment7. Trace the new line of the pattern, I have marked the side with the blue dotted line.  Pay special attention to the new shoulder line when the pattern was spread the line was no longer straight. Tape the top of the right-hand side of the pattern then slash the bust dart in the middle to the apex but not through.
    full bust adjustment8. Move the pattern right the amount needed, marked below in red. Trace a vertical line from the front edge to the cutting line in the middle marked by the red small arrow, separating the grey area from the pattern.full bust adjustment9. Slide the grey area to meet the hem(red area) tape the pattern and retrace the new lines.  Move the dart up or down depending on your needs. All that remains to do is to retrace the new pattern.  Noticed how the armscye never changed nor did the width of the shoulders. However, the bust dart area and underbust have increased.full bust adjustment

For those without a dart as in the Proteus Cardigan for an increment of the bust 2″ or less: A and B Cup

This alteration is almost the same as above except we are not concerned with the bust dart. Find the location of the apex of the bust for this wither you pin the pattern to your body or if you have made a mock-up you will drape this on your shoulders. Mark the apex on the pattern and make a cut from the seam allowance

Mark the apex on the pattern and make a cut from the seam allowance stopping 1/2″ from the apex.full bust adjustmentTrace a line from the hem to the apex the from the apex to the armhole and another line to the shoulder, roughly two inches from the shoulder edge. full bust adjustment

Cut from the hem to the armhole but not trough meaning do not break the piece apart.  Then cut from the apex to the shoulder also not breaking the pattern piece apart. Spread the pattern.  Repeat steps 7, 8 and 9, it is the same method from here on.

Full Bust adjustment using the Pivot and Slide Method

This method is for people who have a difference between 2 to 6″ between the chest and the bust and require multiple alterations such as in the case of a par shape woman with a large bust.

Place a large piece of paper on your work table and place your pattern on top of the paper.  Trace the hole pattern and using a tape measurement or ruler mark the amount the pattern needs to be enlarged in relation to your body measurements. full bust adjustmentPlace a pin on the corner of the armhole, and pivot the pattern towards the markings you have previously made. Trace the new seam allowance from the pin, the side and towards the hem.  Where the hemlines intercept, make a small notch.  I am showing you the position with the red arrows on the right. Trace the whole hemline and few inches of the front seam allowance.

full bust adjustment

Return the original pattern to the starting position and slide down the pattern to retrace the front until it meets with the new traced line indicated above by the blue arrow.  You will have to trace the new hemline between the blue arrow and the original traced pattern.

full bust adjustment

The front has gotten longer in the new pattern to accommodate a larger bust, but the side seam, shoulder, and shoulder with has not changed.full bust adjustment

Whichever method you use it will give you a larger size without changing the shape of the garment. Any questions, send them in as a comment below.

As always it would be most helpful if you just snap a pic and attach to your comment if you have something specific to look at.  That always makes it easier to respond.

Until next time!

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22 Responses to How to make a full bust adjustment to a sewing pattern

  1. Pat Burckhardt says:

    I just love your tutorials and read up on them even if I’m not needing it at the time. When I was young (high school) I had no boobs and I always said I had a better shape from the rear because my bones stuck out but what little I had was very high and I started sewing and realized that I had to move the dart point up about an inch to make the blouse or dress look right. These things really do make a big difference. Now I’m old and on the other side of that fence and will have to make adjustments for more in the front. Thank you for this tutorial and if I decide to make something for myself I’ll remember this to refer back to.

    • Mayra at So Sew Easy says:

      Thank you, Pat, I read all the comments because make me feel we are longtime friends and we hang out sewing all sort of things so thank you for taking the time to comment:)

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  3. Wendy Cookson says:

    Help please, I need to do an FBA but not sure which method to use. I have a 38 inch chest (upper bust) and 48 inch full bust. Which method would you suggest? I am an apple shape but don’t need all the extra width at waist and hips.
    Wendy

  4. Brenda says:

    Thank you Myra! I am so glad to have a fix to the gaping neckline and armseye! I always need an enlarged bust box.
    Do you have any tips on altering a ready made article of clothing for a larger bust and waist?

    • Mayra at So Sew Easy says:

      Hi Brenda, I do but I will have to make a full tutorial, it really depends on the fabric, style and what type of neckline, what do you have in mind? A picture would help me a lot. You can load one as a comment or send me one at my email mayra@so-sew-easy.com 🙂

  5. Kathy in W TN says:

    Mayra, Thanks so much for taking the time to write up this tutorial. I understand how to make the changes to the pattern, but am confused about the amount of change to make. Your size chart includes ease (finished measurements) but doesn’t state how much ease is allowed. Also, what do I do with the 3 bust measurements (upper, full, and lower) and the differences between each? There is no ease included with these measurements. Thanks for setting me straight!

    • Mayra at So Sew Easy says:

      Hi, Kathy, take the size closest to your measurements and adjust. If the adjustment is done properly it will not change the design. Ever! so no matter whether you are an S or 2XL the cardigan should look the same. The measurements are there to let you know what type of adjustments is best for your body (Bust and Chest) the underbust is to let you know if the pattern needs adjustment at a waist level. I will be going over the topic of easy (another large topic) in a different tutorial, stay tuned 🙂

  6. Sandra says:

    Thank you, Mayra, as this will be a big help to me.

  7. Didge says:

    Thank you so much for this information. Nancy Zieman has also a great book on the pivot and slide method, which is very easy to understand and do – just like the methods you have shown. It really is brilliant the way you have colour coded each line to show where the adjustments and also the original pattern is. Thank you once again. It is really easy to understand and do.

    • Mayra at So Sew Easy says:

      You are welcome Didge 🙂 Do you happen to know the name of the book? Pivot and slide method was taught to me by an Italian teacher (Jo Terranova) in her 90’s today. The woman dressed impeccably she is the best teacher I ever had!

  8. Cecilio Valiente says:

    Thank you for this info. It really helps me in my sewing adjustments. I love all the info i get from these articles & newsletters…

  9. Liz Murray says:

    Thank you so much for this – I am trying to add 4 inches each side and 9 inches on the length – I just cut up the original nightie that was sent to me then made a paper pattern. Then added the extra inches needed. Your method is much more effective I would imagine as I am worried about the neckline and armhole. I have attached a picture of the pattern I have made. I am not a seamstress I would rather be making quilts but I have four more of these nighties to make. Any further information about altering patters, I look forward to see on your website. Thank you.

    Here's my pic:

  10. Anne says:

    thank you for the patterns and bust dart adjustments. it makes a huge difference to the fit.

  11. Dara says:

    Thanks Myra, makes a lot of sense to me! I will give this a try.

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