Here's a quick tip where you can set the magnification of "View > Print Size" to reflect the actual physical size of your document.
1. Measure the horizontal viewable size of your monitor or laptop screen. For example: 13.75 inches.
2. Note your horizontal resolution. 1366 pixels for instance.
3. Divide pixels into inches to get your screen resolution per inch. 1366/13.75 = 99.3 pixels/in
4 In Photoshop's Preferences > Units & Rulers, enter this value under New Document Preset Resolutions shown in the screenshot. Save and close.
After that,when you select Print Size,the document and even the onscreen rulers will reflect actual size. Now with Open GL graphics cards being fairly common,the odd magnification needed for those results won't appear jagged.
Alternative method, courtesy of the late, lamented John Slate:
Courtesy of the late John Slate:
John Slate - 3:08pm Jul 15, 05 PST (#7 of 10)
If you want to get exact about displaying print size:
Open a new 500 pixel x 500 pixel file in Photoshop, and set it to 100% (view actual pixels) if it does not come up that way.
Get out a ruler and measure the image on screen in inches.
Divide 500 by the measurement.
This is the resolution of your screen.
Move the decimal point 2 places to the right in that number, and write it down somewhere. Call it your monitor factor.
For InDesign or Illustrator viewing actual size assumes a monitor of 72ppi, so to fine tune actual size in those apps, divide your monitor factor by 72 to get the % view you need for those apps to see same size.
For Photoshop, divide your monitor factor by the resolution (in ppi) of whatever image you are working on to determine the right zoom percentage for that image.
Enter that figure in Photoshop > Preferences > Units & Rulers > New Document Preset Resolutions > Screen > Resolution >. Then you can just select the Zoom tool and click on the "Print Size" button to have your image automatically show at actual print size on your screen.
(You can also enter that figure when you create a new Photoshop document, and that will set the correct print size on all your files, including existing ones.)
This has been the case since CS2.