A note on the FBA

Some time ago I wrote about adding fabric wedges below the waist, especially so there’s enough fabric to cover a large front or back.

The best known reason for adding a fabric wedge above the waist is the Full Bust Alteration. (Lots of possibilities on the upper back and sleeves too, but I’m not going to talk about them here.)

I don’t need an FBA myself, so have no practical experience. It’s a bit silly for me to comment. But I am intrigued by it as an alteration so have been noticing information. Here’s some of what I’ve found, in case it’s of use to anyone.

There’s a list of links about the FBA by Debbie Cook at Pattern Review.

Adding enough fabric for larger cup sizes is not just a matter of adding length and width to the front pattern piece. A good FBA adds a wedge starting from the armhole, so the added fabric is in the middle of the pattern.

Here’s an example of the wedge in position, and it’s relation to the added length and width.
Before – left, after – right.

(wedge about 2 inches)

The photo shows the usual FBA, described in detail in Palmer and Alto ‘Fit For Real People’ p.140 onwards, and also in many McCall’s Palmer-Pletsch patterns. Palmer-Pletsch also have a DVD : ‘Full Busted ? Sew Clothes that Fit !’‘.

Basically, slit up from waist to bust point.
Then angle across to the armhole stitching line at the notch.
Armhole not shoulder, as you may not want to increase the width of the upper pattern. Some people with larger cup sizes may like to open up a wedge to the shoulder as well.
Spread horizontally by the amount needed to go round the bust.

There’s no way of knowing beforehand exactly how large a change to make. It depends on your shape and your personal preferences – how much ease you think looks and feels right for you.

Also slash across to the centre front, and lower the separated section until the waistlines are level. This adds needed length to the front.

(Red lines are new dart stitching lines. Larger cup sizes may look better with the ends of the darts further from the bust point.)

I’m getting more comfortable with the idea of slashing up muslins – it’s the reason we use the cheapest possible fabric ! Write on them, cut them up, keep them for reference. And I’m more patient with not getting fit right at first try.

Bigger darts put more curve in the flat fabric. You’ve added fabric at the centre of the pattern piece, but don’t want the side and waist seams to be longer. The added wedge of fabric also changes the shape of the armhole and the angle of the side seam.

McCall’s fitting pattern 2718 has different front patterns for 5 cup sizes. To make the armhole difference clear, here’s a tracing of the stitching lines for A cup (black) and DD cup (red). (Size 14, the shoulders and necklines are the same.)


The DD front pattern is wider, and the bust dart deeper. But also the armhole shape has changed, and the angle of the side seam. Notice the ‘scoop’ of the armhole – the lower edge of the armhole isn’t horizontal. The changed armhole shape introduces a wedge of fabric from the armhole where more fabric is not needed, to the centre of the pattern, where it is.

– – –

Some people who need a larger front pattern also need a larger armhole and sleeve head, or wider shoulders. But not everyone does. So those are separate adjustments.

If your cup size is larger than B (the size commercial patterns are made for), but your shoulders are not large, the pattern shoulders may fit you better if you buy patterns according to your upper chest/ high bust measurement, not your bust. Vogue size charts for Misses include the upper chest measure, but the Women’s chart doesn’t. I e-mailed them to ask about this, but they didn’t reply.

Debbie Cook’s list of links mentioned before includes several links about choosing pattern size by high bust or full bust measurement.

Ann Rowley prefers to buy her patterns by bust size and do a narrow shoulder adjustment, rather than buying by chest/ high bust size and doing an FBA. Here is her tutorial on the narrow shoulder adjustment.

Ann explains her choice by relating it to her own measurements. You only need to do an FBA or narrow shoulders if your shoulders are small relative to your bust. From Ann’s post, it looks as if the best method depends on :
– if your hips are smaller, like your shoulders – buy pattern by chest/ high bust and do an FBA,
– if your hips are larger, like your bust – buy by bust size and do a narrow shoulder adjustment.
If you’re interested in this, it’s best to read Ann’s comments about why her approach is best for her measurements, and her suggestions for other body shapes. This may be another area where you need to try both to see which is best for you !

– – –

The standard FBA method works for tops with fitted armholes and front shaping darts. Debbie Cook has written tutorials for doing FBAs on different styes of tops, which are here.

And there are many other special cases. Do a web search to get over 3,000 links with examples and suggestions to explore !

I hope you don’t have much difficulty with getting a good fit 😀

– – –

P.S. Here’s Imogen Lamport’s advice for people with large cup sizes on how to look good.
And here’s a post from her on layering tops with a large bust.

P.P.S. More resources :

Silhouette patterns are for B, C, D cup sizes.

Butterick patterns (A to D).
Vogue Custom Fit patterns (A to D).
Simplicity patterns for cup sizes A to D

McCall’s 2718 fitting pattern has front pattern pieces for A, B, C, D, DD cup sizes. (Buy by above-bust chest measure, which is on the Butterick and Vogue fitting charts though not the McCall’s one).

Here is blogger Shams’ fitting advice for people she calls the ‘uber busty’ (larger than D).
And here’s her resources for the busty.
The Curvy Sewing Collective has a series of posts about big darts starting here.

Connie Crawford has a series of master patterns for cup sizes from A to I :
basic bodice sloper with darts
shoulder princess
armhole princess
Video intro to these patterns on fitting for cup size.
Plus a video intro on
using these patterns as a starting point for making your own designs.
The videos refer to the basic sloper with darts (CS1201), but apply to the other master patterns as well.

Step-by-step detail about doing an FBA or an SBA on an existing pattern, from Colette Patterns here.

– – –

Links available February 2011

Explore posts in the same categories: fit of clothes

4 Comments on “A note on the FBA”

  1. alison Says:

    When I first started to do pattern alterations, I found the fact that the pattern pieces looked different from what I recognised to be very worrisome. Though it looks as if the armhole that you end up with after doing an FBA is very different from a “standard” armhole, once the dart is actually sewn shut they will have an identical configuration, which will allow whatever sleeve you use to be stitched in without problems.

  2. Saz Says:

    Hi, thanks for this, it’s by far the most useful resource I’ve found on this subject so far. I’m new to pattern-making, and the only reason I want to get into it at all is to master this particular adjustment. This is going to be a really dumb question for anyone who knows anything about pattern making but here goes! Where you have adjusted the pattern to add the wedge, is the idea to retrace onto a new pattern (ie the gaps are filled in with fabric) or are the gaps darts (to be sewn up)? Or is it a combination of the two? Thanks 🙂

    • sewingplums Says:

      Good question Saz – I hadn’t made that at all clear.

      Look at my first photo, on the right with the wedge added.

      There are two possible darts :
      – the bust dart from the side seam – yes you’ve added extra height to the pattern piece to cover the larger bust, but you want the side seam length to be unchanged, so the dart is deeper.
      – the waist dart if you want one : sew the dart the new width at the waist but tapering to the bust point (well about 1.5 – 2 inches, 3.5 – 5 cm from the bust point), not right up to the armhole. The new dart is wider, as you’ve added more fabric across the pattern piece to accommodate the larger bust. But you want to get the waist seam back to the original length.

      Please ask again if that isn’t clear.

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