Ever notice that when you view a Photoshop file at 100%, it’s not actually 100%. It’s almost always larger, depending on your Mac. That’s because when Adobe coded 100% view, it was based on all screens being 72 dpi. Unfortunately that hasn’t been the case in many years. Try it out. Create an 8.5 x 11 inch document in Photoshop, set the view to 100% and hold up a Letter size piece of paper and you’ll notice the difference.

The problem is that modern computers/screens are much higher resolution than 72 dpi. The key to seeing things actual size in Photoshop is to make Photoshop and your screen the same resolution. It’s a simple process.

Determining your actual screen DPI:

  1. First, go to your System Preference and click the Displays icon. Make note of your monitor’s resolution (you may have to click the Scaled radio button on modern Macs). My iMac is set to the maximum resolution of 2560×1440.
  2. PXCALC

  3. Next, visit PXCALC and enter that screen size resolution from the step above if it doesn’t automatically populate this info for you, and in the Diagonal Size box enter the physical dimensions of your screen and hit enter. In my case it’s 27 inches. (see image above)
  4. On the little screen info area to the right, you’ll see stats about your screen, the first of which is the actual dpi of your screen. In the case of my iMac it’s 108.79. (see image above)

Setting Photoshop’s screen DPI

  1. Open Photoshop’s Preferences (Command + K) and click the Rulers & Units item from the list on the left. In the dialog window, you’ll see New Document Preset Resolutions in the top right corner.
  2. Photoshop screen resolution settings

  3. In the Screen Resolution box (just below the Print Resolution box) enter the DPI you got from step 3 above. Leave the Print Resolution setting at 300, as that is the typical resolution for commercial printing. (see image above)
  4. Hit OK in the dialog box and you should be good to go.

Now when you view your Photoshop document at 100%, it should actually be an accurate 100%. Try the Letter sized paper test I mentioned at the start to see if it worked for you.

There’s one caveat though. This is for SCREEN RESOLUTION ONLY. If you want to view your 300 dpi print resolution images at actual size, you don’t set your view settings at 100%. Instead, under the View menu choose Print Size instead of 100%.