Fitting The Larger & Smaller Bust – Professional & Technically Accurate Methods – FBA – SBA

As you may know, I make and sell basic blocks for pattern cutters, fully graded in wide size ranges. This has been a bit of a hobby for me over the past 30 years, and something I started doing when I worked as a Senior Fashion Lecturer at the world-renowned Manchester ‘Hollings Faculty’ at MMU. It was a bit of a side hustle for me at the time and since retiring and moving to France I have now made my love of drafting and grading into a full-time job! In this series of articles I am looking closely at fitting at the bust – if you want to learn a professional and technically sound method then you are in the right place!

Did you know that most commercial pattern companies make their patterns to fit a B cup size? If your cup size is larger or smaller than this, then you begin to realise that the garments you are making from these patterns will never fit you perfectly. Most basic blocks that you can buy out there are also drafted to a B cup. I have adapted my basic bodice block, and my new torso blocks to cater for a larger cup size. I re-balanced my front blocks to be wider than the back, this allows for larger cups C/D and easier Full Bust Adjustments (FBA) for larger cup sizes. Of course, Small Bust Adjustments (SBA) are also possible.

Many commercial patterns and regular basic blocks leave the full busted lady, and there are many, with no choice but to select a pattern size to fit her bust size. This results in a garment that fits poorly everywhere else. The smaller busted lady is also faced with the same problem but in reverse. 

I encounter this problem myself as I am an F cup and have a very small skeletal frame. As a pattern cutter and pattern grader I am acutely aware of how the changes I make to a pattern in one area impact the fit of the garment in other areas. In certain areas a change of a millimetre (a tiny fraction of an inch) can have an impact. In other areas centimetres (fractions of an inch or more) are required. If you simply add on extra (or subtract) all around the pattern you are creating even more fitting problems!

If you google FBA (Full Bust Adjustment) or SBA (Small Bust Adjustment) you can find many articles and blog posts on the subject. As with any information you discover on the internet there are some good articles out there and some shockingly bad ones! Some of the methods suggested will lead to more fit problems than you started with. I truly have seen some shocking ones!

If you are an AA or A cup, then you may get away without making any pattern adjustments. It also depends on the style of the garment and your fit preferences. If you are a C or perhaps a D cup, then you may also be fine.

HOW DO I KNOW IF I NEED TO MAKE A BUST ADJUSTMENT ON MY PATTERN?

Do your blouses gape or fail to sit properly at the centre front?

Is there a bump or folds of fabric above the fullness of your bust?

Do the shoulders of your garments never sit correctly?

Does the fullness of the bust shaping or the location of the darts not match your own bust shape?

Does the front hem of your garment not sit level with the rest of the hem line?

Do the darts of the garments you are sewing fail to ‘aim’ towards the fullest part of your bust?

If the fit issues mentioned above sound familiar to you then it’s likely that you would benefit from adjusting the bust area of your patterns. Once you have solved these problems you will never look back!

The goal of an FBA or SBA is to adjust the bust without altering the fit in all other areas of your garment. When making changes around the bust area we must also consider where our bust sits. I can certainly say that my bust level (and bust points) are much lower now than they were when I was a student. This is a detailed topic on its own and I have a useful blog post on raising or lowering the bust level of a pattern if you want to delve into this area in more detail. I suggest you make sure your bust point and bust level are correct first before continuing with a FBA or SBA.

Please head over to this post first – Adjusting the fit at the bust -part 1 – bust level and bust point apex.

 

Raising or lowering the bust level is quite straightforward in theory – knowing how much you need to adjust it by is more difficult to work out. This is where making a toile is essential. I covered the importance of making a toile in a previous article if you would like to know more about that.

If you want to forge ahead and don’t want to go down a rabbit hole, you can also take an educated guess by placing the pattern piece or block to your body and marking on where your bust level and bust points are. I know for myself, I will always need to lower the bust level on a commercial pattern or a basic block if I haven’t drated to my own personal measurements. You can make an ‘estimated’ adjustment first and make a trial garment, then perfect the fit of the bust level and bust points as required.

You can find much more information on how to find a bust point on any commercial pattern by looking at this post on my blog page.

Let’s look at how to locate the bust point and bust level on a pattern that has no darts in this post This will help you to understand the bust area and illustrate how to relocate a dart to the new bust level. In the next article in this series I will go into more detail, but for now lets look at a straight style.

This method will work well for adding more fullness over the bust with my straight top block and dartless blouse block.

You will need the following equipment:

Some pattern cutting paper

A pair of scissors

A sharp pencil (2H is best)

Some sticky tape

The pattern or basic block you would like to adapt.

A ruler and a tape measure.

Take your pattern piece front and place accurately to your body. Make a mark where your bust point lies – remember this is the fullest part of your bust. To do this accurately you must be wearing a good supportive bra. When working with a finished pattern remember it will have seam allowance added so please allow for this.

Your bust point may be higher or lower than the pattern. The technique below can be used as a solution to both.

If you have no darts on the pattern then simply make a mark to identify your bust point and your bust level. You now have the location marked for the next step of making and FBA or SBA.

If you have a dart or darts on your pattern, you will need to find the centre of each existing dart. Connect this central point to your own marked bust point – then continue to mark in new dart legs, connecting both legs to the new bust point. Darts need to be shortened by at least 2.5 cm (1 inch) for sewing. If you sew a dart right to the bust point it will look very unsightly!

I am aware that I am using some technical language here – if you are asking yourself, what on earth are dart legs! Here is a little help. If you would like to know a little more about this then you can find much more info on my blog page!

Don’t forget to fold in any darts that are already on your pattern, as they would sit when they sewn, this gives you the correct shaping if you are placing the pattern piece to your body. If you have made a ‘toile’ then the darts will be sewn in.

You now have the correct bust level and your darts are aiming towards your bust points. This is a great achievement and will vastly improve fit. If you need to make an FBA or SBA you are now ready to go ahead and make the adaptations.

Let’s look at making an FBA (SBA is just the reverse of an FBA) to a pattern that has no dart at all, for example a t-shirt pattern. Larger busts look much better in garments with bust darts, so we will also introduce a dart into this basic pattern shape to perfect the fit. Larger busts also benefit from a side seam dart, this technique can also be used to add darts to any of your existing swim suit, or jersey based patterns where you would like a better fit over the bust.

PATTERN PREPARATION – Lets look at a FBA on a straight top pattern with no darts to begin with.

If your pattern has seam allowance, most commercial patterns have 1.5 cm (9/16″) seam allowance, then mark this seam allowance with a pencil inside the pattern piece.

 

1. 1. Place your pattern to your body and mark the bust point if you haven’t already done so.

Place your pattern on the table. Drop a perpendicular line from your bust point mark to the hem of your pattern piece.

Mark a line on your pattern where you would like the extra fullness to form, the shoulder is best for a very full bust that has a lot of volume above the bust points. You can also select a position under the armhole or use both if you want to fit a very large bust

Now you need your scissors – slash up the vertical line (from the hem) right up to your marked bust point. Continue up the line (or lines) you marked for your extra fullness. STOP at the point where the seam allowance starts.

Keeping the pattern piece slightly attached at the pivot point open the pattern piece up. If the garment is being made with stretch fabric you don’t need to open the pattern up as much as a garment made with woven fabric, half of the extra you would like to add is enough.

How much will you need to open the pattern? This all depends on the shape of your bust and how many cup sizes you want to increase the pattern by. There is a 2 cm bust girth difference per cup size so try 1 cm (as you have 2 sides to the garment) as a starting point. You can then adjust again to perfect the fit. The illustration below shows you where you need to measure.

You will need to introduce some extra length at the centre front. This allows for the extra fabric you need to travel over the larger bust and prevents the front hem from dipping upwards. It’s a bit like the difference between walking over a small hill and a large mountain range, and the walk if from the Center Front Neck Point – to the CF hem point. I have seen methods where there is no extra added to the cf length and while you can get away with this with a tiny adjustment on a small size, the fitting implications for using this method are horrific for any substantial adjustment.

Cut along the bust level from the CF to the BP and drop the centre front by the quantity you require, try 2 cm ( 13/16″)  per cup increase and adjust as needed.

Now let’s introduce the new dart. Let’s put a french dart in at a position radiating from the waist level. Plan a dotted line where you would like this new dart to be. Cut up the dotted line, keeping it attached by a couple of mm (1/16″) right at the end. Pivot the side panel back to the hemline. If you already have a side seam dart then this planned line will be through the center of the dart you already have.

Draw in the new dart, connect the opening of the dart mouth to the bust point. . Find the centre line of the dart and draw this in. Take the dart apex back at least 2.5 cm for a small adjustment. The larger the bust the further away the dart tip needs to be from the bust point. This is also a matter of personal preference. (If you have an existing dart then plan this line through the center of the dart and this will simply make that dart larger)

It’s worth noting here that you have only made changes to the pattern where you need them. The hem circumference remains the same as does the side seam length, once the dart is sewn in. There are no changes to the armhole or the shoulder or the neck. This means that the back of your pattern piece is cut as normal. The center front is also still nice and straight which is very important.

Also please keep your eye on the bust point and bust level while making the changes, this is often lost in all the methods I have seen so be sure to keep to your original measurements and check.

I can’t promise that you will achieve the perfect fit on your first attempt. By making small adjustments to the fit using the methods explained you will certainly get there.

Here are a couple of alternative options for you to try – the first is the same method but with the extra fullness added for a bust that is voluminous above the bust point, the second is the same method applied to a pattern with an existing side seam dart.

 

This subject area is vast and it’s impossible to cover all aspect of bust adjustment here. If you would like more information, for example how to make a SBA ( the exact opposite of the steps we took above) then continue reading at my blog page www.modelistecreative.com. I am also happy to answer any questions you may have. Keep a look out on my YouTube channel for useful pattern adaptation videos too.

www.youtube.com/modelistecreative

Join me in the next article in this series where I will show you how to make a FBA and SBA on my basic bodice blocks.

If you would like to learn professional pattern cutting from an industry professional with over 30 years industry experience and a highly qualified Senior Fashion Lecturer, then please take a look at my online courses. All details on my blog

Happy Pattern Making & Sewing,

Nicola