The Custom Zoom control on the Zoom toolbar displays the current zoom percentage (where 100% means Actual Size).
The Custom Zoom control
You can change the current zoom percentage by typing a number in this box or by selecting a percentage from the drop-down list. If "Page" is selected in the Custom Zoom control, the document window always displays the entire page regardless of the size of the application window.
You can quickly Zoom In, Zoom Out and Zoom Full Page using the other buttons on the Zoom toolbar.
Note: The current zoom percentage is also used when printing the picture. For more information, see Print.