The calculation formula for the indexing plate (also called the division angle) can be determined based on the required division accuracy and the type of indexing plate used. Some common indexing plate calculation formulas are listed below:

1. Equally divided scale lines arranged in a straight line:

Graduation angle = 360 degrees ÷ total number of scale lines

2. Scale lines that are equally divided into arcs (such as arithmetic arc scale lines):

Graduation angle = 360 degrees ÷ total number of scale lines

3. Non-uniformly divided scale lines arranged in a circular arc:

Graduation angle = (360 degrees × scale spacing) ÷ circumference

Among them, the scale spacing refers to the angular difference between adjacent scale lines, and the circumference is the length of the circle covered by the scale lines on the dividing disk.

It should be noted that the effective number of digits and precision of the indexing disk will also affect the accuracy of the indexing result. Therefore, in actual use, it is best to confirm the specific specifications and calculation formula of the indexing disk with the manufacturer of the indexing disk.

In addition, when using the indexing disk for precise division, it can also be combined with an indexer or a digital display device to more accurately control the division angle.