Thursday, November 7, 2013

FBA for garments without darts - tutorial, part 2

The swedish version is found here

This post on FBA is not done only because it's fun, but because I haven't found anything satisfactory out there - and I have searched a lot. I had to develop my own method, and it works!

For FBA introduction I recommend reading part 1. It is found here.

I will now show you how to make a full bust adjustment (FBA) on a garment without darts, such as a t-shirt. The pattern I'll use is 'Rose Top' from the book Sy! Från hood till skjortklänning by Jenny Hellström Ruas. This tee is cut with a slightly A-line.

The first time I made Rose I did the classic mistake, i.e. cut one size larger (size L) to give the boobs enough room. Then I ended up with this amazing (hmm) piece:

You can clearly see that it is very tent-like around the shoulders and waist, but still tight across the bust. This is not what we want, unless taking the family camping - just bring the tent poles and get installed!

Here we go.

#1 Select your size and trace your pattern

If I go by my waist and high bust measures, I end up right in the middle of size M and L according to sizing table (my real bust measurement puts me between L and XL, but that we ignore for now). I will sew my top in a stretchy jersey so I choose to start from a size M.

According to the pattern table I would have to increase my bust width by 8 cm (just over 3 inches) = 4cm(1,5'') /half pattern, but the stretchy fabric makes me doubt that I need that much and I now decide half of that should be sufficient. That is 2cm/half pattern.

Trace your pattern.

Front size M, no alterations. 

#2 Finding apex

If you're sewing in non stretchy fabric then you can "wear" your pattern and mark apex, but for stretchy fabric this is not so simple since it tends to have a life of its own when worn. If you don't belive me, put on a stretchy top and mark with a pin your apex. Remove the top and compare with the mark on the pattern. I bet you they are not in the same spot! For me they are a good 3cm apart, see photo below. 

Yellow points at apex for stiff fabric, blue points at apex for stretchy fabric.

Now I will continue my work from the blue apex.

#3 Do FBA

Time to cut and spread! In common fashion we now mark the FBA lines to be cut, but since we don't have any darts we only have to bother about the apex. 

IMPORTANT! Before you cut - measure the sideline of the pattern carefully. Write it down. If you have any notches (I do) then measure the distance to it from the armpit and write it down. You'll need these measures later.

My sideline is 42,5 cm and the distance to my notch (I only have one) is 14 cm.

Now you can cut, spread and tape your pattern!

Adjusting for my 2cm as planned.

But HOLD YOUR HORSES!! What were you thinking? We didn't want any darts! And if we don't have darts, we are making the waist wider and the sideseam longer, right? RIGHT??

Yup. Pretty much about here most tutorials end, but calm yourself, I won't leave you hanging - now we have some fixing to do! :-)

#4 - Adjustment to avoid altering the waist

Now there are a couple of important steps.

First, grab a tape measure or a ruler and measure on your body the distance between your armpit and your waist. It doesn't need to be super accurate. I measure roughly 30 cm /12''. Mark this on your pattern.

From the waist marking and down to the hem we want to remove the same amount as we added through the cut, 2cm in my case. This is the dotted line.

Now grade the dotted line from the waist to the bust cut - we want the boobs to fit now, don't we. Mark your new pretty sideline all the way up.

Now the garment will get the waist size it was designed for, but have plenty more boob space. LIKE.

#5 - Adjustment to avoid altering the length

If you remember the boob drawing from tutorial part 1, I explained that a bigger bust needs more fabric down the front for the garment to keep its length. So far in this FBA we have made the entire front longer, since we don't have any darts. That would make the front hem look like a sour mouth. We don't like sour mouths, we like indifferent, straight mouths. So now we need to take action.

In step #3 I told you to write down your sideline measures. Now we need it.
Measure the side again along your new sideline.

My original measure: 42,5cm
My new measure: 44,8 cm
Difference = 2,3 cm. (approx 1'')

Now mark, from the bottom along your new sideline, the difference you measured (2,3cm).
Grade towards the waistline cut, see the blue line in the photo (psst, ignore the red line down the bottom. I am blaiming the baby). Now, just to be sure, measure your sideline again, between the armpit and the blue line so that is is identical to your original measure (42,5 cm).

Blue line marks the new hem.

Now that this is done there is only one thing left. Adding your notch to its new location. In step #3 I measured it to be 14 cm below the armpit so I measure and draw it in place.

New notch location.

All you have to do now is cut around your altered pattern or trace it again and you are done!!! You have now constructed a nice pattern that goes together like a dream - the sleeve and the back pattern pieces won't have a clue what you've been up to! Sneaky, sneaky!

Just to prove this alteration visually I've placed my new size M pattern on top of the old one, the unaltered size L. If you look closely you can see that the size M has smaller armholes, slimmer waist but MORE bust allowance!!! That's just perfect! 

#6 - Moment of truth

Results? Strike a pose...

And just a little historic reminder from times when things were suckier:


  • If you have a very large bust you may actually want to sew a bust dart. The fabric will try to form one anyway. It is a matter of how much wrinkles in the side you can tolerate. If you do make a dart then you'll skip step #5.
  • If you have a tummy that fancies a little extra fabric you may be tempted to skip step #4. That's okay BUT you'll have a quite big adjustment to to in step #5 then. If you're sewing a striped fabric, like me, the hemline will show that it is not cut straight off. If you want you can make this less obvious by doing half of the step #5 adjustment and instead make the backpiece longer until they match up. Note that it would make the garment longer.

Good luck!



  1. That's an awesome technique. Too bad that I have a bust far too large to use it though :/

  2. Thank you! Your longer explanation than many books I've read really helped! I had the proverbial AHA moment!

  3. This is awesome. Can't wait to try it. Thank you!

  4. Thank you so much for this and your other FBA tutorial. I've been sewing for years and it's the first time I've really understood. You're right many other tutorials end before the final parts. I now want to remake my wardrobe with FBAs ☺

  5. This is cristal clear thank you very much

  6. I blogged about a jumpsuit I made using your tutorial and used one of the images above linking to this post, hope you don't mind.

  7. Good post but I was wondering if you could write a litte more on this subject? I’d be very thankful if you could elaborate a little bit further. Appreciate it!
    Prom Dresses


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