Pattern adjustment for a large bust – FBA tutorial

A pattern adjustment for a large bust is also called an FBA (Full Bust Adjustment) and helps ensure that self-sewn fashion fits well even with a larger chest.

The most important things at a glance

• In this post, we give you an overview of pattern adjustments for a large bust
• We explain what an FBA (Full Bust Adjustment) is, why it is needed, and how it works
• Blogger and DIY fashion expert Anne Burmester provides you with the best tips and tricks for pattern adjustments for large cups in this guide
• To ensure your pattern adjustment is a success, this post includes an FBA tutorial where we explain everything step by step

Full Bust Adjustment: Pattern Adjustment Guide

What is an FBA (Full Bust Adjustment)?

An FBA/Full Bust Adjustment is an adjustment for a full, i.e., large, bust. We are adjusting the pattern to our own figure to create a garment that fits us better and looks more flattering.

Who needs an FBA?

Sewing patterns—just like ready-to-wear clothing—are mass-produced and therefore cannot fit everyone perfectly. Most sewing patterns are designed for a B cup size; consequently, anyone who does not have a B cup actually needs to make an adjustment.

Depending on the garment, however, other cup sizes might still fit well, making the effort unnecessary—for example, if the top is very loosely cut, if gathers allow for more room, or if the fabric is stretchy.

Can beginners also manage a pattern adjustment for a large bust?

Absolutely! The most important thing about an FBA is to dare to try it! You should take enough time and use enough fabric, and be open to experimenting and testing. Adjustments rarely succeed on the first try; you have to feel your way through, but it is worth it!

Why is an FBA important?

Adjusting for a large bust is important so that the garment fits the wearer in the end. If no adjustment is made despite having a large bust, the garment will fit poorly and pull or wrinkle at the end.

Women with a large bust will recognize this: the top is too big overall, especially at the shoulders; wrinkles form at the armhole and from the hem diagonally upward, and the front hem pulls up. An FBA avoids all this by creating space exactly where it is needed!

From which cup size does a pattern adjustment in the chest area make sense?

You should definitely perform an FBA from a D cup size—or even a C cup size if you are making fitted garments or if the top does not fit properly.

Which sewing patterns are suitable for an FBA?

Basically, any pattern is suitable. Depending on the pattern, however, different approaches may be required. For beginners, tops with classic bust darts coming from the side seam or patterns with longitudinal seam lines are best.

Where can I find a suitable sewing pattern for an FBA?

You should sew what you like and what you want to wear—that is precisely when it is worth adjusting the pattern and perhaps sewing it again.

For your first FBA, for example, the Maris Dress is a very good choice, as the woven fabric is somewhat easier to work with when it comes to darts. Jersey or elastic fabrics are not recommended for your first FBA, because you cannot see exactly what happens to the fit when your fabric stretches.

How do I determine the bust point?

The bust point is the highest point of the breast—it is the pivot point of the FBA and almost always corresponds to the nipple. Depending on the size and shape of the breast, this point is in a different place for every woman.

The best way to find the bust point is to hold the paper pattern up against yourself in front of a mirror, align the center front and shoulder seam, and mark the bust point with a pen.

How do you choose the right starting size for an FBA?

Generally, the size of a top is determined by the bust measurement. If you have a large bust, however, this measurement does not match the rest of the upper body. Therefore, instead of the full bust circumference, we measure the high bust circumference.

To do this, do not measure over the fullest part of the bust; instead, guide the tape measure so that it sits above the bust. This measurement roughly corresponds to the bust circumference of a B cup and is therefore a good starting point—other measurements, such as waist and hip circumference, can also provide information about the correct size.

How do I perform a pattern adjustment on tops without bust darts?

For patterns without bust darts, the dart must be added later. Anne describes how to do this in her step-by-step FBA guide further down in this post.

My pattern already has bust darts—do I still have to do an FBA?

Yes, because darts are used wherever the garment is meant to be fitted. However, darts do not dictate the cup size.

I am sewing a top out of jersey—is an FBA still necessary?

Jersey or other stretchy/elastic fabrics adapt better to the figure than firm fabrics. Nevertheless, an FBA is recommended; otherwise, the top may be too large overall due to the bust measurement, or the fabric will be stretched too tightly across the chest, causing wrinkles.

Can I add bust darts later?

Unfortunately, an FBA can hardly be done after the fact. A large bust needs not only width but also more length, because the path over a large bust is longer, and this length cannot usually be added effectively later.

Sometimes wrinkles form from the armhole that already seem to form a dart themselves. You can sew this dart, but keep in mind that your armhole will become smaller, so you should re-cut the armhole afterwards so that sleeve and armhole still match and your arm has sufficient space and freedom of movement.

What helps if it fits at the bust but is too wide at the waist?

The extra width added at the bust should be removed at the waist if the pattern is not loosely cut and the fabric is not intended to just fall straight down from the bust point. To do this, we use darts placed below the bust point to bring the fabric back to the figure.

What you need for an FBA (Full Bust Adjustment)

You should have a few tools ready before you start:

• the pattern you want to adjust
• measuring tape
• Scissors^*
• Marking pen^*
• Pins^*

How does pattern adjustment work with seam lines?

If your top is not one piece but has seam lines, such as princess seams, you can also perform an FBA. Instead of using darts, the extra width is achieved through the seams.

You can read how to do this in Anne's Full Bust Adjustment post; there you will also find instructions for cut-on sleeves or if the pattern already has darts.

Moving, correcting, or splitting darts

An FBA requires darts that take away fabric where it is not needed. Darts point to the bust point because that is where the most room is required. If a dart is not placed correctly or if you want to move it, you can change it; Anne shows you how in her dart guide.

Where should the bust dart be placed?

Darts point to the bust point because that is where the most width is needed.

Classically, a bust dart is constructed under the arm, which removes the length that the side seam does not need, but which is required for the path over the breast. Because the dart is under the arm, it is hardly noticeable.

Another dart is located under the bust, because it removes the width needed for the roundness of the breast with precision.

Can you leave out bust darts?

No, if a dart is simply left out, the fabric that would normally disappear into the dart will wrinkle, and the seams will no longer fit together.

When to sew an FBA?

Ideally, as soon as your own cup size is larger than the one provided in the sewing pattern (usually a B cup). In exceptional cases, an FBA can be omitted if the deviation is only minor and the pattern is very loosely cut or the fabric is stretchy.

Are darts cut open?

Darts are usually not cut open, as the seam needs sufficient support in the fabric.

In exceptional cases, with very thick fabrics, you can (after sewing) cut the dart open to within 1.5 cm of the tip and press the fabric apart so that it does not show through.

Why darts?

Darts take fabric away where it is not needed and thus ensure a smooth fit and good freedom of movement for the garment.

For example, the fabric needs more length across a large bust, but the length at the side seam does not change due to the large bust. The dart ensures that the length in the side seam fits again!

In which direction are darts pressed?

Darts should be pressed properly so that the seam lies flat. When pressing, you can place a piece of folded fabric next to the dart so that the dart does not show through.

Vertical darts are pressed towards the front/back center; in other words, the dart allowance on the left side of the fabric points towards the center.

Horizontal darts are usually pressed downwards; this follows gravity and is therefore particularly durable.

However, it can make sense to press bust darts upwards, because the seam then lies in the shade and is invisible to an observer meeting us at eye level. However, the dart should only be pressed upwards if it does not then sit in the armhole—why not just give it a try!

Happy simple sewing, Anne & Sabine