See the November 2014 addendum at the end if your version is missing this feature
Photoshop has many tricks, but automatically adjusting for the actual screen ppi (pixels per inch) to display accurate print dimensions is not one of them. You need to train the old dog for this new trick. It is quite straightforward and from that point on, when you choose “View/Print Size” it will display the actual size. Of course, large print sizes may not fit the screen but you will get a good sense of proportion.
This discrepancy has two sources. The first one is Adobe settings for units which uses 72 ppi for the screen resolution although most screens today provide higher resolution than that; not by much but higher nevertheless. The second source of the problem is that different monitors show different “actual” resolution than the nominal reported one. So, the crucial thing to do is to measure the pixels/inch for your specific monitor. Here is how.
- Create a blank document that has 300 dpi print resolution, 9″ x 9″ in dimensions. This will create a blank document 2700×2700 in pixel dimensions
- Fill it with white if it is not already filled
- From the menu choose “View/Print Size”
- With an accurate ruler and using great care not to damage your screen measure the displayed dimensions in inches. In all likelihood, it will be a good deal smaller than 9 inches
- Divide 9 inches by the actual measurement you obtain from the screen which will provide the correction factor. I am not using an example since this number may vary from one screen to another.
- Now, go to “Edit/Preferences/Units & Rulers” and find the screen resolution. Most likely it is set to 72 pixels/inch
- Multiply the current ppi, 72, by the correction factor you calculated above and enter that in the screen resolution field. Click OK.
The resulting screen resolution may have a decimal fraction, that’s OK and it will not necessarily be 96 ppi either. My screen’s actual resolution turns out to be 94.299. Your number will likely be different from this
From now on, when you choose “View/Print Size” your screen will display the actual dimensions of the print. I told you it was simple, but I wish Adobe could find a way to automate this.
Note March 16, 2013: Ole Nielsen reports that Photoshop 13.0.4 Creative Cloud-version does not support “View/Print Size” option. I do not have first hand experience but am reporting what I learned.
Note November 2014: I have realized during a workshop I was running that Adobe pulled out this feature from Photoshop CS6 on the ground that it was difficult to implement and support on retina displays. Interestingly, it found its way to Photoshop CC and living there happily thereafter! The solution they officially recommend (the help forum where they made this suggestion has disappeared, 12/21/2016), if your updated Photoshop CS6 has lost this capability, is to upgrade to CC. I will be cynical here and say “how surprisingly insightful!” There is another solution which involves downloading a script from their site. It simply calculates the necessary zoom ratio and tells the user. You can probably, with some patience, can do the same with trial and error and note the zoom percentage and use that in the future when you want to view the image in actual print size on the screen. You will see many participants in various forums, from Adobe heavyweights to welterweight fanboys, all arguing that Adobe had no choice but to remove it. I am glad at least the CC users got it and I have learned to live with alternate solutions. I wish all would be a little more frank, just a little!