Large-Bust Adjustment: The Gotcha

People new to block making and patternmaking, especially those with little or no sewing experience, often don’t understand the instructions for creating blocks.  They simply just follow along step-by-step.  It is often difficult or impossible to see if and when an assumption is being made within those instructions. Even if you do sometimes understand an assumption – e.g. that the block will be made with a B-bust-cup, you sometimes don’t understand that fully.  For example: when you use your bust measurement to make the Bodice Block – how can it then be too small in the bust?  Most cases it will be, if the instructions are assuming a B-bust cup.  Even if you do realise that you have to do a Large Bust Adjustment to create a bigger dart, you still may be missing part of the picture; that the underarm width will be too big for you. If you don’t really understand the full ramifications of a B-bust-cup, you will make your B-cup block, then do a Large Bust Adjustment (LBA) from that block, and then…. be caught by the Large Bust Adjustment Gotcha.

The Problem

I made a block to my measurements, and I was aware that the result would be a B-bust-cup.  The toile was very ill-fitting.  As well as being tight in the bust, it pulled from the armhole to the bust.  It seemed big in the underarm area also – but that was being complicated by the pulling from the armhole to the bust. It was obvious that there wasn’t enough ease in the bust, and I needed a Large Bust Adjustment.  The issue with the underarm and armhole, according to all the books I read, was due to the small bust dart…  if I did a LBA, that would fix the problem. A few of my textbooks said something along the lines of:  “if a loop forms in the armhole, that what is needed is a Large Bust Adjustment “. Which I did. Then it justbecame more wrong.  It went from being too tight in the bust to enormous everywhere. Of course, I thought I had made a mistake and increased the bust cup too much…. but that wasn’t the problem.

A Clue

There was a clue in one book; I can’t remember what book and exactly what is said, but it was along the lines of:   “if your upper body is smaller, and your bust is much larger in comparison, draft the block for a smaller size and add a large bust adjustment.”  But I couldn’t understand what exactly is “a smaller size”  – which of the measurements of the smaller size did I use?  Those particular instructions I was using at the time didn’t create the front and back separately, and I just didn’t understand what “a smaller size” meant, in real terms. A clue that didn’t help me much then, but eventually led me to realise what creating a block with a B-bust cup really means.

The Answer

The definition of a B-Bust-Cup is the Upper Bust is 2 inches smaller than the bust.  A C-Bust-Cup would be 3 inches smaller in the Upper Bust, and a D-Bust-Cup 4 inches smaller (etc.) So if you make a block using your Bust measurement, and the block is going to create a B-bust-cup.  It is assuming the Upper Bust measurement of the B-cup (2 inches less than the bust), and the amount of ease in the underarm is worked out on that Upper Bust measurement.  If you have a D-bust-cup, you will end up with an extra 2 inches ease on top of whatever amount of ease a B-cup will have.   A  DD-Cup will end up with 3 inches more ease than the B-cup…. etc. The image titled Large Bust Adjustment Gotcha further up this page shows the extra ease I ended up with by creating a block for a B-bust-cup, then doing an LBA. The brown block is my correct block, the purple area is the unnecessary extra. Remember that the block is half the body, so that extra ease is on both sides of the body.

For a correctly fitting block, you need to do the bust shaping from the correct Upper Bust measurement.

Making the Block to your Upper Bust

The problem is that if you draft a block to your bust measurements, and you don’t have a B-bust cup, you need to make adjustments to the Upper Bust (armhole area) as well as the bust. I think it’s more sensible to use the Upper Bust to draft your block. You can then create the correct bust cup dart following on from this.  This is the way I do in my instructions.  See my article: Why Upper Bust rather than Bust?  for details of how this works.

Blog Articles

9 Responses

  1. Hi Maria,

    Thank you for the valuable article. I discovered your website yesterday, and have already learned so much with regards to the rationale behind some of the methods of pattern cutting. One thing I cannot get my head around, though, is choosing a (b cup) pattern based on upper bust measurement. For example:

    My upper bust is 40” and my full bust is 46”. If I were to choose a pattern drafted for a 40” bust, then the upper bust area of said pattern would be drafted for a 38” measurement, making it measure a bit too small. So logic tells me that I should choose a pattern drafted for a 42” bust (So that the upper bust area will fit my 40” measurement), and then carry out a 2” FBA. Is this correct?

  2. Hello Zahra

    Yes, a pattern with a 42″ inch bust will have an Upper Bust of 40″. So buy a 40″ pattern and do an LBA. You will need an extra 4 inches, so spread 2 inches at the Bust Point on the half-pattern.

  3. I’ve never been successful using a FBA (or LBA), no matter which method I used and whether I used a sloper-to-be or a commercial pattern..

    The solution to my problem was surprisingly simple: Draping.
    I wore a knit tank top with negative ease (and a well-fitting bra underneath) and pinned a gingham-like fabric piece to the tank top along CF, at the shoulder, apex, arm pit and waistlne at CF and ca. 10cm/4” towards the side, making sure that 1) CF was perpendicular to the floor, 2) HBLs were at the arm pit and from CF to the bust point and 3) there was adequate length from shoulder to apex to the waistline.

    The dart(s) appeared like magic! I pinned them (one bust and one waist dart because the total angle of one single dart would have been SUPER HUGE), When I was happy with the fit (no wrinkles, no folds, no pulling – yahoo!), I traced the suppose shoulder seam, armhole, side seam and waistline with a sharpie, unpinned the fabric, marked the darts with the sharpie, removed the pins, et voilà!

    All what was left to do was to transfer the contours and the darts to a pattern sheet (I like transparent ones) and label the front piece.

    Happy draping! 🙂

  4. I simply ran out of patience making dozens of blocks with lengthy instructions and explanations. Unless you love digging into formulas and memorizing rules, do yourself a favour – make a body double. I literally spent years making my block. Nothing was working, the block was wrong, the center lines were not in the centre. The revelation came when I picture myself from front, back , and sides and draw gridlines in Photoshop.

    One shoulder longer than the other, uneven shoulder slopes, tiny scoliosis that pulled my right side hips skewing the pattern, different breasts, bulges on sides.

    We are so used to our asymmetry in a mirror over the years, that we don’t notice any flows.. Well , manufacturers create symmetrical patterns that fit the younger population – slim, cup-B , etc.

    make your body double

  5. Hi Tia
    Every person is different and prefer different methods. If you look through my site, you will see I have a ‘body double’. I had a body cast made for myself 15 years ago. Despite this, I did not get a good result with draping, and draping is definitely not my thing. I hate it.

    Having said that, if that’s your thing, I completely understand.

  6. Hello again Tia,

    As I’ve mentioned in my previous answer, draping is not my thing. I have a ‘body double’ (a body cast) , but did not use it for drafting my block.

    I have a block that fits well, and I have worked out the asymmetry in my body, though I don’t actually draft my patterns to take it into account – it isn’t that important to me.

    I prefer to draft my block using my measurements, and I have a perfectly fitting block from it.

    Thank you for giving an alternative option; there are people who prefer using measurements, and there are people who prefer draping.

  7. Hi there.

    Thank you, I appreciate that draping works for you.

    I didn’t have any luck with draping when I tried it years ago, and now it is a moot point as I have a perfect fitting block…. Which I drafted using my system which is quite different to most systems. I have received a huge amount of feedback to show that it works very well.

    I would say that most people find it easier to follow step-by-step instructions than to work out their block by draping.

    But of course there will be some people who prefer the other way.

  8. I have the added problem of being rather short and have to reduce the bodice across the armhole and above the waist, but I’m getting there…

Leave a Reply

Your email address will not be published. Required fields are marked *