Sewing Blog

Find Your Fit: How to Make a Full Bust Adjustment

When it comes to using commercial patterns, it is important to remember they are drafted based on a bust that is a B-cup size. Since these companies must market their patterns to the majority of consumers, and the B-cup is the most common size, this makes good sense. But, certainly not all women have a B-sized bustline, which means the commercial pattern must be adjusted before any fabric is cut. Learning how to make this adjustment can make all the difference in constructing garments that not only mimic ready-to-wear, but in fact surpass boutique pieces. Why? Because your handmade garment will fit you perfectly.

Let's go step-by-step through the process of a full bust adjustment!

How to Make a Full Bust Adjustment

Full bust adjustments can be done in a variety of ways. Most depend on the position or type of on the bodice pattern or if no darts exist at all. Since side bust darts are the most typical way garments are shaped to conform to the contours of the breasts the method taught here is based on this and is the easiest adjustment to make. Learning how to modify these darts is an important technique every garment sewer should know.

Not only for general fitting purposes, but since many original designs are based on basic slopers which contain the side bust dart, adjusting the fit of this dart must be done first before any other design changes are made.

Measuring your bustline

Full bust measurement + high bust measurement

The process of adjusting for a fuller bust begins by measuring your bustline in two ways. First measure the fullest part of your bust. This is the typical measurement you use to determine pattern sizing. Now measure your high bust. This is the circumference measurement just under your armpits and just above your bustline. Note the difference of these two measurements as it will determine your new pattern cup size and the amount that needs to be added to the pattern:

●      Around 2": B cup
●      Around 3": C cup
●      Around 4": D cup
●      Around 5": DD cup

Next, gather the following supplies:

●      The bodice front pattern with a side bust dart
●      A sharp pencil for marking the pattern
●      A ruler
●      Clear tape
●      Scissors for paper cutting

Here are the steps for the FBA:

1. Select the pattern size based on the high bust measurement and use the bodice piece based on that size. Using this measurement to dictate size instead of the full bust measurement will ensure the shoulders and waist fit better.

Basic bodice front with side bust dart
2. Hold up the pattern to your body lining up the center front and shoulder seam. Make sure it is positioned as accurately as possible to your body. Now mark a dot to indicate your bust point.

the bust point
3. Draw three lines on the pattern:

●      From the bust point down to the waist, or hem, that is parallel to the center front grainline.
●      From the bust point to the side seam perpendicular to the center front grainline.
●      From the bust point to the center of the armhole curve.

Cutting your pattern
4. Using the marked lines as your guide, cut the vertical line starting from the waist, or hem, up to the bust point, pivot and continue cutting to the armhole stopping just short enough to make a small hinge. Next, starting at the side seam cut to the bust point, again stopping short to leave a hinge at the bust point. Lastly, because when the new darts are formed the waist or hemline will be skewed, cut a horizontal line from the center front to the vertical line.

5. Using the following chart as your guide separate the vertical lines by the amounts detailed below:

●      For a C cup, separate the lines by ½"
●      For a D cup, by ¾"
●      For a DD cup, by 1"
●      For a E cup, 1 ¼"
●      Etcetera

6. As you separate the vertical lines new dart formations are created at the side and armhole. Place paper under these openings and tape in place. Also tape the bottom portion of the center front piece to align with the new waist or hemline.

Bust point + new dart apex
Measuring dart points
7. Next, draw in the new side bust dart, or the FBA. Mark a line from the bust point (the one that never moved) to the side seam so it is perpendicular to the center front grainline. Measure 1 to 1 /2” (less for small adjustments, more for larger adjustments) from the bust point towards the side seam to mark the new dart’s apex. Now measure the distance at the widest point of the opening that was created where the side cut was made and use that to determine the width of the new dart. Using that measurement draw in the bottom dart leg.

8. Lastly, true up the side seam. Fold the line of the bottom dart leg up to the top leg and crease in place. While holding the dart in place and using a thumbtack or pin, poke a line that will serve as the new side seam cutting line. The pattern is now ready to use.

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What's your most common fit problem when working with commercial patterns?

14 Comments

Miriam Wood

I am amazed. I am a beginner and this is so good to remember how to make full bust adjustments. Thank you.

Reply
Miriam Wood

I am amazed. I am a beginner and this is so good to remember how to make full bust adjustments. Thank you.

Reply
Joy

I can never buy patterns off the shelf which fit, having a short waist, high DD bustline and apple shape middle. I need all the help I can get. I love to sew and believe with high hopes you can instruct me!

Reply
Jan

I do this time and time again and every time it ends up in total failure. Try as I can I cannot, I repeat cannot get the length to drop down enough to provide coverage over the bust. I end up with folds, about two or three between arm and bust – this must be the fabric that should be dropping over the bustline. I do not tally with the dart as on the pattern, I am much much lower. I am I have to admit at my wits end. If I lower the dart before doing this I end up with the dart too low down. Any solutions – surely I am not alone in needing this adjustment?

Reply
Linda Reynolds

I don’t understand where the folds are occurring – where between the arm and bust? – at the underarm? armhole? I can’t visualize where ‘between the arm and bust’ is. Usually when a LBA is needed other bodice adjustments are needed as well. Before you begin to locate your bust point and start the LBA, make sure the neckline on the pattern is where you want it and that the shoulder line and armhole are correct as well. If not make those adjustments first, than try making the LBA .If the folds you are referring to are at the armhole the LBA will not resolve or cause this – this is a totally separate adjustment. As far the LBA not covering the bust enough then try making the adjustment even larger. I hope this helps.

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Hannah

I’ve measured my high bust which is 36″, and my full bust is 38″, as the difference is 2″ this would mean I was a B-cup, but in the shops I tend to buy C-D cup. Do you know why this is by any chance please?

Reply
Stephanie

Bra cup sizes and pattern cup sizes are different measurements. 🙂

Reply
Sarah Turnbull

The high bust / full bust ratio doesn’t work for some figures (eg those with muscular shoulder blades). I am in the same situation with a 35″ high bust and a 36″ full bust, wearing a D cup bra.

You might need to look at your full bust vs underbust. In my case, 36″ full bust vs 30″ underbust clearly shows I am on the busty side.

It’s tricky – I’m sticking to skirts for now!

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Donna

I am confused. I have a 40″ high bust and 43″ full bust so i can see that i must have a C cup. Now if i choose a pattern based on my high bust and do a FBA for a C cup it says to widen the the vertical cut by 1/2″. Doesn’t that mean that my pattern would only increase by 1″ to fit a 41″ bust leaving me 2″ short? Or should i be widening the vertical cut by 1 1/2″ to provide the additional 3″ ?

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Kim Bankton

Thank you for your post. Why do you move the apex in the adjustment?. I would think the apex location should not change. To keep the apex in the same measurement from CF, I can not use the original waist dart legs but have to move them toward CF to line up with my apex. For example, my apex to apex measurement is 9″, or 4 1/2 from CF. When I add a one inch adjustment, my waist dart center line moves away from the apex by 1″, so I have to move it back to maintain my apex distance of 4 1/2. Please advise, and thanks very much.

Reply
Andrea Nangle

This is a helpful explanation of a FBA however I think Step 7 is not clearly enough explained or demonstrated in the accompanying picture:
“Now measure the distance at the widest point of the opening that was created where the side cut was made and use that to determine the width of the new dart. Using that measurement draw in the bottom dart leg.”
This is where I come unstuck.

Reply

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