Womenswear Measurements - Some Thumb Rules

1. Relationship between Across Front, Across Back and Across Shoulder

Here Across front is taken at mid armhole. The three measurement taken together are used to draft and gauge armhole shape.

For woven fabric Across front should be 1.5" less than Across shoulder and Across Back should be 0.5 inches less than the Across shoulder.

2. Back and Front Armhole

The Back Armhole should be 1/2 to 5 1/8" bigger than the front Arm Hole

3. Front and Back Neck Width

Back Neck width is 1/2 inches bigger than the front neck width.

Read the full article here and here