Get Better Fitting Garments Using Full Bust Adjustment (FBA)

“Making pattern adjustments can seem overwhelming at first. Why isn’t this fitting correctly? How do I fix this? Why doesn’t this pattern fit me? Sewing patterns, like clothing, are drafted to a standard size and most patterns are drafted for someone that is a B or C cup size. However, unlike patterns and clothing our bodies are as individual and unique as our personalities. Most of us aren’t “standard” nor should we ever hope to be. Part of the reason we sew our own clothes is to get that custom fit and build the handmade wardrobe out our dreams. This means that altering patterns goes hand in hand with making clothes. It is all part of the process and a skill to practice on just like you do with your sewing.

Today, I would like to introduce you to the Full Bust Adjustment, or FBA. The majority of women with fuller chests typically pick the pattern size based on their fullest bust measurement. This can lead to the shoulders and neck being too large and having to take in the rest of the garment just to accommodate your chest. I want to first walk you through how you know if you need a Full Bust Adjustment and then I will show you the steps to making a FBA on your pattern piece.

How to Calculate a FBA:

Start by measuring your Upper Chest. This is the measurement that goes from your shoulder blades at the back right up and over your chest at the top.

Next, measure around the fullest part of your chest starting around where your bra strap is at the back and coming around to the front.

TIP: Make sure you are wearing the bra you intend to wear under the garment you are making. Different bras, depending on the compression or padding, will give you different measurements. Undergarments will make a big difference!

Finally, measure around your natural waist.

Next, circle your measurements on the pattern’s measurement chart. Below I will give you Option A and Option B to illustrate how to determine if you need a Full Bust Adjustment.

FULL Bust Adjustment

Option A:

Here you can see that the upper bust is in the large sizing, however the bust and waist are both in the XL. You may notice that the difference between the upper bust and the fullest part of the bust are more than 2” (5cm), however the waist and the bust are in the same sizing. In this
case, I would NOT do a Full Bust Adjustment and instead trace a smaller neck and shoulder and then grade out to the XL for the bust and continue the sizing for the rest of the garment.

Full Bust Adjustment

Option B:

Here you can see that the Upper Bust and Waist are both in the Large sizing, however the Bust is XL. This is an indication that a Full Bust Adjustment is needed. When the bust is the only measurement falling outside your main measurements, this is an indication that you need a FBA.

Full Bust Adjustment

Now for the Math… Once you have determined that you need a FBA you will need to calculate how much of a FBA is needed for your garment.

In this example the waist measurement is 34”. This means that we will trace the LARGE as our
base pattern size. Since our base pattern is a size large we will use the largest measurement from the large bust as our B measurement. (40”)

A. Your Full Bust measurement   ________ –

B. Largest Bust measurement of size you are tracing   ________ =

C. Amount extra needed  ________

For example: 42” – 40” = 2”

D. Take C and divide it in half because   ________ / 2 = _______
we are only altering half of the pattern.

For example: 2”/2 = 1”

So we will be adding a 1” FBA to our pattern.

Adjusting Your Pattern:

For this alteration, you will want to have your pattern piece traced out in the size you measured for you upper bust and waist onto pattern tracing paper. For our example we traced a size Large
to start with. You will also need scissors, tape, ruler and a pen. I will demonstrate marking a Full Bust Adjustment for a bodice with darts, but you can use the same lines and principles to make a FBA alteration on dartless tops and jackets as well.

Start by marking the apex. The apex is the point where the fullest part of your chest is. Typically it is 2-3cm above the bottom dart and in line with the side dart.

Once you’ve found the apex, you will draw a line up through the bottom dart to the apex and label this line A.

Full Bust Adjustment

Next, draw a line from the apex out to the armscye. Typically there is a notch there that you can aim for. If the pattern does not have a notch then you can place a mark approximately 2/3 down and 1/3 up, as shown in the picture. Label this line B.

The next line will be coming from the side seam, directly through the middle of the side dart towards the apex. Label this line C.

Full Bust Adjustment

Your final line will be half way between the apex and waist. Draw a horizontal line and label it D.

Ok, now onto cutting and spreading.

Start cutting from the bottom of A up to the apex. At the apex, pivot and cut out towards B. When you get almost to the end STOP and leave what we call a hinge. Do not cut all the way through B.

Full Bust Adjustment

Next, start from the outside of C and cut in towards the Apex. Leave a hinge at the Apex.


On a seperate piece of tracing paper mark your FBA amount. Ours is 1” (2.5cm)


Take your cut pattern piece and line up the edges of your line A with the 1” marks. Tape into place.

Full Bust Adjustment

Finally, cut across D and drop D so that it lines back up with the waist. Tape into place.

To finish, mark the middle of where the top of the new dart will go half way inbetween
the 1” adjustment area. Use your ruler to connect the dart to the old dart legs. Repeat for the side dart.

You will notice that by doing this the darts are bigger giving more room through the chest area, but we haven’t altered or changed the neck or shoulders, and the waist will go back to the same size once we mark and sew the new darts.

Full Bust Adjustment

Once everything is marked, I recommend retracing your new design onto another piece of tracing paper and testing the bodice before making your new garment. This will allow you to check and make sure your math was correct and you don’t need to move or shift the darts.

Full Bust Adjustment on Patterns Without Darts:

Typically, if you need a FBA for one type of pattern, you will most likely need it for all future patterns. All FBAs are treated relatively the same regardless if there are darts or not. It will be the same four lines (A,B,C, D), the same cuts and hinges and then blending back in the waist or opening up new darts that you can then use to create more shape. This means that you can FBA
a jacket, dress, box top, even something with princess seams. The FBA may take a little bit of practice, but once it’s mastered you will beam with so much pride and love your better fitting garments!”

Leave a Reply