Show pixel dimensions of an image without opening it, on a Mac

Updated October 3rd, 2020.

When working with images it’s important to know their dimensions (how many pixels horizontally and how many pixels vertically, 640 x 480 for example).

Sometimes you want an image with many pixels, either because you want it to take up a lot of screen space or because you want it to print well, and sometimes you want an image with not very many pixels, because you want the image to load quickly on a web page or to be transferable via email. This leads to a need for multiple copies of some images- one saved at high resolution, another saved at low resolution (and maybe others in between).

Of course you can open up an image in Preview, or Pixelmator, or Photoshop, and find the image size via the app’s menus. But that takes a bit of time and all that opening and closing becomes tedious, especially if you don’t find what you want on the first try.

What you really need is a way to look at an image’s icon in a Finder window and know what its dimensions are without opening it.

There are two ways to do it.

Show the pixel dimensions of images in the Finder’s Icon View

The picture below shows the results of a search for image files with the word “calendar” in their names. This is List View, and it’s not very helpful when it comes to showing actual dimensions, although the “Size” column does give us an idea of which image files might be the higher-resolution ones and which might be the lower-res ones.

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Image files with the word "calendar" in their names, "Size" column gives some indication of relative size but not actual dimension.
Image files with the word “calendar” in their names, “Size” column gives some indication of relative size but not actual dimension.

(It’s too bad that there’s not a column for “Image Dimensions” but that’s the way it goes. We will work around it.)

A better view for image files is the Icon View, which one can easily switch to (on a window-by-window basis) in any of three ways:

  1. From the menu: View/as Icons
  2. From the keyboard: Command-1
  3. By clicking a button (see below)

Now we’re in icon view. The icons might be previews of what’s inside each file, and they might not; it depends on a setting which we look at shortly. The important thing is, we still don’t know how big each file is.

In the Finder, go to the View menu, choose “Show View Options,” and then check the box for “Show item info” in the panel that appears.

Voilá! You now see (in tiny blue type) the dimensions of the images below each icon!

(If the box for “Show icon preview” is not checked in the View Options, check it. Unchecked, the window displays a little faster but you get generic icons. Checked, you see preview icons and the window displays a tiny bit slower. I vote for checking the box that shows the icon preview.)

The settings in the View Options panel are specific to the window you are looking at. You can “Show Item Info” for some windows, and not for others, same as you can show some Finder windows in Icon View and others in List View, etc.

(“Show Item Info” does more than show dimensions of images- for folders, it shows the number of items contained, and for movies, it shows how long the movie is. See below.)

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I like showing images in Icon View, with preview icons, and with item info showing. It’s the easiest way to see dimension information for a lot of images at once. But there is another way to get the dimensions of an image without opening it, and that way involves a simple Get Info.

Show an image’s dimensions via Get Info

The Finder’s “Get Info” command opens up a small box with a lot of info. You can trigger Get Info by clicking on an icon (just once- to select it) and then going to File/Get Info, or by clicking on an icon (just once- to select it) and then Command-I. It’s an easy keyboard shortcut to remember.

Built into the Finder’s Get Info box is a section showing an image file’s dimensions. It’s in the Get Info box’s “More info” section. That section may be closed up and that might be why you’ve never noticed it before. But, if you click the little triangle next to “More info” in a Get Info box, you’ll see it.

The “Get Info” method is easy, but you have to do it on a file-by-file basis, which can become almost as tedious as opening files and checking their dimensions within Preview or Pixelmator or Photoshop. Personally, I vote for showing a window in Icon View, previews on, and item info checked. Be sure you make the icons big enough to be useful- you can do that in the View Options box with the Icon Size slider, or in the Finder window itself (but only if the Toolbar and Status Bar are showing- see the View menu for those).

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Any questions?

Copyright 2008-2023 Christian Boyce. All rights reserved.