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How to do a FBA...

...Full Bust Adjustment

Blocks and dressmaking patterns traditionally cater up to a bra cup size of B or C. If your cup size is larger than the standard measurement, achieving a fit that is comfortable and flattering, is not as difficult as you may first imagine.  Continue reading to find out what you should do if you’re a D, DD, E or larger cup size. 

What is a Full Bust Adjustment (FBA)

An FBA will create more space around the front of the block in the bust area only and this is done by increasing the size of the bust dart.

Our block has been drafted to accommodate up to a C cup. Work out your cup size, below, to determine whether you need a FBA.

Work out your cup size

Your cup size in the block will not necessarily correspond to your bra size.

You will need two measurements to determine this:

The high bust measurement: This is the area of your chest just below your underarms.

  1. The full bust measurement: This is the area around your ribcage and over your bust apex.
  2. undefined

If the difference between these two measurements is more than 5 cm (2”) then an adjustment is required.

Use the following chart as a guide

Select the correct block size

Base your size selection on your high bust measurement + 5 cm. This is your bust measurement for up to a C cup so select the correct size on the block size chart above.

For example, let’s assume that your upper bust measurement is 88 cm. Add 5 cm to it to work out your bust measurement on the chart - and the size you would be if you had C cup size breasts.

88 cm + 5 cm = 93 cm corresponds to a size 12. Your full bust measurement, however, is 98 cm though - 5 cm larger than the cup size of the block. This means that you will need to do a FBA and add this 5 cm (bust differential) to the front of the block.

As the block front is on the half you must divide the 5 cm bust differential by two and add the 2.5 cm to the half block. 

If you’re using the digital size layered block, print and tape the A4 sheets together and cut out or trace the front. If using a hard copy block trace the front in the correct size.

A. Take your high bust measurement and your bust measurement

B. Using a red marker. Draw line A through the centre of the waist dart. Extend it through the dart point towards the bust point

C. Draw line B through the centre of the bust dart. Extend it through the dart point towards the bust point. The intersection of A and B is called the bust apex

D. Draw line C from the bust apex to the mid armhole

E. Cut through line A starting at the waist and continue cutting through line C just short of the armhole

F. Cut through line B, starting at the side seam just short of the bust point

G. Cut a piece of paper, large enough to accommodate the alterations, and place it underneath the slashed block.

H. The measurement between the slashed line A should measure half of the bust differential measurement (BDM)

I. Tape to secure

J. Adjust the difference in the waist height by cutting through the centre front section and aligning it to the longer section

K. Fill the gap at the waist with a piece of paper

L. Draw a line through the centre of the widened darts and form an apex where the two lines intersect

M. Draw in the new wider bust and fisheye darts

N. Trace the new block front

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