Enter the probing depth (mm) and the gingival margin level (mm) into the Clinical Attachment Loss Calculator. The calculator will evaluate the Clinical Attachment Loss. 

Clinical Attachment Loss Formula

The following two example problems outline the steps and information needed to calculate the Clinical Attachment Loss.



  • CAL is the Clinical Attachment Loss (mm)
  • PD is the probing depth (mm) 
  • GM is the gingival margin level (mm) 

To calculate the clinical attachment loss, subtract the gingival margin level from the probing depth.

How to Calculate Clinical Attachment Loss?

The following steps outline how to calculate the Clinical Attachment Loss.

  1. First, determine the probing depth (mm). 
  2. Next, determine the gingival margin level (mm). 
  3. Next, gather the formula from above = CAL = PD – GM.
  4. Finally, calculate the Clinical Attachment Loss.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

probing depth (mm) = 9

gingival margin level (mm) = 3

CAL = PD – GM = ?