"Binocular overlap refers to the visible overlapping portion between the two eyes of a stereoscopic vision system. In other words, it describes how much of the viewed scene can be seen by both eyes as opposed to by just one of the eyes.
Binocular overlap.
Source: David Johnson, University of Utah
The visual field varies from person to person, but typically extends 60 inward (toward the nose) and 100 degrees outwards, and typically 60 degrees above and 75 below the horizontal meridian. As such, the binocular overlap region is 120 degrees horizontally (-60 to +60 degrees for each eye). Since each eye can see about 160 degrees, the binocular overlap is 120/160 = 75%."
http://sensics.com/what-is-binocular-overlap-and-why-should-you-care/#:~:text=Binocular%20overlap%20refers,120/160%20%3D%2075%25.