Binoculars' magnification is determined by the length of the eyepiece divided by the central distance of the object. For example, if magnification is five times' normal, the image appears five times closer than it really is. Most hand-held binoculars use less than this.

Binoculars are categorized based upon the magnification they produce times the objective diameter, which is expressed in millimeters.

The field of view is the distance in width visible at 1000 yards or the number of degrees able to be viewed. The optical design used in a particular binocular determines what the field of view is.

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