How to do FBA on a dartless shirt?

Embarking on the journey of garment sewing can be an exhilarating experience, filled with the promise of creating unique and personalized pieces that perfectly complement your style. However, for those with a fuller bust, the excitement can sometimes be accompanied by the challenge of achieving a flawless fit. In this comprehensive blog, we'll unravel the mysteries of Full Bust Adjustment, breaking down the process into manageable steps that empower you to tailor your garments to fit your body beautifully.

What is a full bust adjustment?

A Full Bust Adjustment (FBA) is a technique used in sewing to alter a pattern so that it accommodates a fuller bust while maintaining the correct fit in other areas of the garment. This adjustment is particularly relevant for those with a significant difference between their upper bust and full bust measurements compared to the standard size sewing patterns.


Do you need FBA?

To determine whether you need an FBA, measure your high bust (your upper chest, just under your armpits) and bust and mark those measurements in the size chart provided in the sewing pattern. Choose the size closest to your measurement based on high bust measurement.

If the pattern size difference between your high bust and bust is more than 1 patterns size, It is recommended to do an FBA.

How to calculate your FBA?

To determine the amount that you will add to the pattern for your FBA, you will need to do a little math.

Step 1. Measure your high bust. Say your high bust measurement is 44” (113 cm). This places you at size 20 in our size chart. This is the size you need to cut out.

Step 2. Measure your bust. Say your bust measurement is 49” (125 cm). However, size 20 bust measurement in our size chart is 46” (117 cm). You need to calculate the difference between your bust measurement and the size chart measurement: 49” (125 cm) - 46” (117 cm) = 3” (8 cm).

You need to add the difference of 3” (8 cm) to increase the bust volume of the pattern. This is your FBA.

Step 3. Considering that the pattern piece is one half of the bodice, you need to add 1.5″ (4 cm) to the bust area.

How to locate your apex?

When you do FBA on a garment with a dart, you stat at the tip of the dart. In the dartless garment you will need to find your bust apex, which will be your starting point.

Measure distance from your shoulder and the fullest part of your breast (as established above – your nipple). Then measure the distance between fullest part of your breasts and divide it by half.

On the front bodice, measure the vertical line from shoulder (equal to measurement of distance between the fullest part of the breast) and horizontal line from centre front (equal to half of distance fullest part of your breasts.

Your apex is where those lines meet!


How to do the FBA?

Step 1 - Draw. Starting from apex, draw a line towards the side seam (line 1 (red)). Draw another line from apex to the armhole and straight down to the hem (line 2 (blue)). Finally, draw another line from line 2 (blue) to centre front (line 3 (green)).

There are no strict requirements where to draw these lines, but make sure you keep the shapes as indicated in the drawing.

Step 2 - Cut. Now you will have to do some cutting!

Cut line 1 (red) from side seam to apex but not completely through.

Cut line 2 (blue) from hem to apex and then to armhole, but not completely through.

Cut the green line all the way through.

Step 3 - Spread. You need to add the required width directly to line 2 (blue) that went from apex to the hem.

Spread your lower bodice (yellow) down & to the right. Keep spreading until the width between the 2 blue lines is half the FBA amount you need. Make sure to keep the green lines parallel to each other. Tape everything down.

When you have your pieces in the right position, fill the gaps with extra pattern paper and tape them down.

Step 4 – Draw new dart. If you want to eliminate the bust dart, you have to redraft it. Draft two lines from the apex towards the side seam (line 4 (purple)). Cut out the dart along these lines.

At this stage, you can decide to keep the dart.

If you want to eliminate the dart, continue to Step 6.

The dart will help you to keep straight side seams. In case you decide to close the side seam, you will have some flare our to the sides.

Step 6 – Close the dart. Cut along line 2 (blue) from the hem to apex, but not all the way through. Cut the top edge of newly drafted dart (line 2 (purple)).
Close the dart by pivoting at the apex.


Step 7 – Trace. Trace the altered front bodice. Make sure to check if the side seam of front and bodice match. Since you added length to the front bodice, you might need to add length to the back bodice as well!

The art of Full Bust Adjustment is not merely a technique; it's a game-changer that allows you to take control of your sewing destiny. No longer confined to ill-fitting patterns, you now possess the skills to tailor garments that not only embrace your curves but do so with grace and precision.

Through understanding your unique body shape, selecting the right patterns, and navigating the intricacies of the FBA process, you've unlocked the secrets to achieving a customized fit that celebrates your individuality. The frustration of tight busts, awkward pulls, and compromised comfort are now relics of the past.

As you venture forth into your future sewing projects, armed with the knowledge gleaned from this guide, remember that the Full Bust Adjustment is not just a technique; it's an embodiment of empowerment and confidence. Every stitch is a testament to your ability to conquer challenges and create garments that are not only well-fitted but also a true reflection of your personal style.

Happy sewing, and may your future projects be a tapestry of perfectly fitted, confidently worn creations!

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