Monday, February 15, 2016

Doing an FBA (Full Bust Adjustment)

What the heck is an FBA,  I hear you say?

Well, today I'm going to teach you what it is and how to do it.

What is an FBA?

FBA - short for Full Bust Adjustment - is an adjustment done to the front bodice pattern so that your bodice will fit around your boobs without pulling, creeping, flattening your boobs when you wear your bodice/dress.  

It's a way of adding cm's/inches to your pattern - just at the front where you need it and not at the back where you don't need it.

And an FBA is done to a big bust.  Most patterns are made for a B-C cup so if you are a D, E, F, G etc. you'll need to do an FBA to your pattern.

How do you do an FBA?

For this tutorial I've chosen my MiSS FOX DRESS pattern.  It has a bodice and skirt and the bodice is made for a C cup.  So if you are over a C cup then you'll need to do an FBA.

Let's get started:

Step 1 - You'll need to take an Upper Bust Measurement (B) and Full Bust Measurement (A).  The UBM will go around you above your bust and up under your armholes.  The FBM - you'll measure around the fullest part of your bust.

Step 2 - Let's say your UBM (B) is 40" and your FBM (A) is 44".  That is a difference of 4".  So, you'll need to add 4" to your front bodice pattern.

Step 3 - Find the size you'll be starting with by using your UBM which is 40".

Step 4 - The above image shows that Size 14/10 has a bust of 40".  So you'll be using Size 14 and not a Size 18.....that is good news!

Step 5 - Trace out your Size 14 pattern and let's begin the FBA.
Step 6 - Rule a line - parallel to the CF (Centre Front) - that goes from the shoulder to the waist through the waist bust dart point.
Step 7 - Rule a line from your first line out to the middle of the bust dart through the side bust dart point.

Step 8 - Now rule a line from the bust dart point up to the armhole nick.
Step 9 - Finally rule a line at a 90 degree angle to the CF, half way between the waist bust dart point and waist line.
Step 10 - Ok, now you've got your lines ruled up you'll now be cutting these lines.  Note:  you won't be needing the line from the shoulder to the bust point.

Step 11 - Place some extra paper under your pattern.  
  • Now cut the line from the waist to the bust point and out to the armhole - don't cut right to the end.  Leave about .5cm attached.
  • Now cut the line of the bust dart but don't cut right through.  Leave about .5cm attached. 
  • Keep the CF stationary and open the waist to armhole line out the measurement you need.  In this case the UBM is 40" and the FBM is 44".  So that's a difference of 4".  As you only need to add the 4" to the front and the pattern piece is half of the whole front you would divide the 4" by 2 which will give you 2".  So you'll need to spread the pattern pieces 2".  That will then open out the side bust dart.

Step 12 - Lastly, cut the line from the CF to the waist bust dart and move it down so that the bottom edges are level.

Step 13 - To Redraw the Darts - at the waist bust dart point find the half way point.  In this case it's 2.5cm/1".  Mark a dot and then draw in the new dart from the waist up to the dart point and then down to the waist.  Sticky tape or glue pattern pieces in place.

Step 14 - To Redraw the Side Bust Dart, you'll need to do a measurement from your shoulder to nipple to find out where you need to start your dart from.  
  • So take that measurement and rule a line down from the shoulder to the bust point parallel to the CF.  Mark a dot for the bust point measurement. This dot should be in line with the dot your marked for the waist bust dart.
  • Now rule a line out at a 90 degree angle to approx. where the side bust dart point begins and mark a dot.
  • Rule a line from the side seam notch of the dart to the dot at the bust and then back out again to other side seam notch of the dart.

Step 15 - All you need to do now is true up the waist and side bust darts.  So, fold the waist dart toward the CF and redraw the waist line with a tracing wheel and fold your side bust dart up and redraw the side seam with a tracing wheel.

Tahah!  You've now done an FBA to your bodice pattern.  Well done!

I hope this has answered all your questions regarding an FBA.  If you enjoyed this tutorial why not pop over to my fb group and get more help to your questions.

Till next time - Happy Sewing!

Ann Martin is the owner/designer of 1 Puddle Lane - Pattern Studio.
With over 30 years experience in the Fashion Industry she brings a wealth of knowledge on everything from Patternmaking and Sewing to Design.
Ann currently lives in Australia and is always working on new pattern designs to create.


  1. Thanks for the tutorial. Hopefully this will help with my bodice fitting issues!

  2. This really helps explain the fitting, Thanks.

  3. When adding the shoulder-to-nipple measurement do you not take into account the shoulder seam allowance? Also, that measurement for me is 11 or 11-3/8" (even with my most supportive bra) and puts the bust dart point almost at the same latitude as the waist dart point. Will that be a problem? Thanks!