Customize menu > Viewport Configuration > Viewport Configuration dialog > Statistics tab
Right-click a viewport label. > Configure > Viewport Configuration dialog > Statistics tab
Use these controls to display statistics in the viewports concerning the number of vertices, polygons, etc., in the scene and/or the active selection, as well as a real-time count of the number of frames per second displayed. To toggle display of the statistics in a viewport on the fly, right-click the viewport label (for example, Perspective) and choose Show Statistics.
Polygon Count—Enables the polygon count display.
Triangle Count—Enables the triangle count display.
Edge Count—Enables the edge count display.
Vertex Count—Enables the vertex count display.
Frames Per Second—Enables the FPS count display.
Total—Displays only the statistics for the entire scene.
Selection—Displays only the statistics for the current selection.
Total + Selection—Displays the statistics for the entire scene and current selection.