Status bar > Grid Setting Display
The grid setting display shows the size of one grid square. This value is constant in the active viewport. It does not change if you zoom in very close or zoom out very far.
Procedure
To change the size of one grid square, do one of the following:
Right-click the 3D snap toggle directly below the Grid Settings Display.
On the Home Grid tab, change the Grid Spacing values.
That value is displayed.