Ease in Bodice: Joseph-Armstrong

In the article Why Upper Bust rather than Bust?  the conclusions I come to are based what I see in other block making instructions.  In that article, I state how much ease Aldrich & Armstrong’s block send up with at the level of the Bust and the Upper Bust, and therefore this article is showing (proving) how I came up with those figures.  The other related article is: Ease in Bodice: General.


When making a block using Joseph-Armstrong’s directions, you will end up with:

  • Approx 5.25 inches (13.25 cm) ease in the underarm
  • Approx 3.25 inches (8.25 cm) ease in the bust

Read below for how I came up with these measurements.

Firstly… A Misconception

For quite a while I thought Aldrich’s bodice block had only 2 inches ease in the bust. The width of the Bodice Front is the Bust Arc plus .25 cm ease, and the Bodice Back is the Back Arc plus .75 inches ease.

My mistake was thinking that the Bust Arc plus the Back Arc equaled the Bust Measurement.  (Totally my mistake, nothing to do with the Joseph-Armstrong’s directions.  I am just flagging this in case there are others out there making the same mistake I did).

Back Arc & Bust Arc ≠ Bust Measurement

Joseph-Armstrong’s directions for taking the Bust Arc and Back Arc measurements are as follows:

Bust Arc: “Center Front, over bust point, ending two inches below arm-plate on side seam”.

Back Arc: “Center Back to bottom of arm-plate.”

Even though I did read these directions in the Taking Measurements pages, it just didn’t sink in.  I kept thinking that the Bust Arc & Back Arc were just a redistribution of the normal bust measurements; e.g. the front was a larger proportion of the total bust measurement than the back.  I thought it was the bust measurement divided unevenly.

According to Armstrong’s Measurement Chart (Fourth Edition), the Bust Arc + the Back Arc are consistently 1.5 inches more than the bust measurement.

Here I’m using two sizes as examples:

Size 6: Bust = 34 inches.  Bust Arc = 9.25 inches, Back Arc = 8.5 inches.  Therefore Back + Front Arcs = 17.75 inches x 2 = 35.5 inches.

Size 10: Bust = 36 inches.  Bust Arc = 9.75 inches, Back Arc = 9 inches. Total Front + Back Arcs = 18.75 inches x 2 = 37.5 inches.

This means that the width of the Bodice Front and the Bodice Back are 1.5 inches more than the bust, and in the instructions another 2 inches ease are added.  Therefore there are 3.5 inches ease in the width of the block.

Note: In the Fifth Edition of Armstrong’s book, the difference between the Bust Arcs are reduced to 1.25 inches, therefore the total ease is reduced from 3.5 inches to 3.25 inches.


The Back Arc + Front Arc come total 1.5 inches more than the Bust. Added together to the 2 inches ease added in the instructions (see above image for details), the width of the block at underarm level is 3.5 inches more than the bust measurement.  (Note that this was for the book I was using at the time: the Fourth Edition.  In the Fifth Edition, the Back Arc/Bust Arc & Bust measurement difference is 1.25 inches, therefore the block width is 3.25 inches more than the bust measurement).

Ease in Bodice Block: Underarm & Bust

See the image below for the details of these measurements:

  • Approx 5.25 inches (13.25 cm) ease in the underarm
  • Approx 3.25 inches (8.25 cm) ease in the bust

Green = Upper Bust, Red = Bust

  • The green measurements are the underarm measurements.  Added together then multiplied by two (since the block is half the body) gives a total of 39.22 inches. Less the actual underarm measurement, 34 inches, results in approx 5.25 inches (13.25 cm) ease at the underarm level.
  • The red measurements are the bust measurements.  Added together then multiplied by two gives a total of 39.26 inches.  Less the actual bust measurement results in approx 3.26 inches (8.28 cm) ease.

Go back to the >> Analyzing Other Bodice Block Making Instructions Menu

3 Responses

  1. I just wanted to say a massive thank you for your blog. I cannot tell you how many years I have been using Armstrong’s blocks and have been making this mistake for years! until I finally decided to google it and found you. I now understand!
    Thank you !!!!

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