What Is an ICNS File?

Apple Preview is the easiest way to view an icon file on macOS. Use XnView MP on Windows

By
Tim Fisher
Photo of Tim Fisher, Lifewire GM and Writer
Tim Fisher
Senior Vice President & Group General Manager, Tech & Sustainability
  • Emporia State University
Tim Fisher has more than 30 years' of professional technology experience. He's been writing about tech for more than two decades and serves as the SVP and General Manager of Lifewire.
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Updated on August 9, 2023

What to Know

  • An ICNS file is a macOS icon resource file.
  • Open one on macOS with Apple Preview, or on Windows with XnView MP or Inkscape.
  • Convert to PNG online with CloudConvert or CoolUtils.

This article explains what an ICNS file is and how to open one on your computer, plus how to convert one to a different image format like PNG, ICO, etc.

What Is an ICNS File?

A file with the ICNS file extension is a macOS icon resource file (often referred to as the Apple icon image format) that macOS applications use to customize how their icons appear in Finder and in the OS X dock. They're equivalent in most ways to the ICO files used in Windows.

An application package typically stores the ICNS files in its /Contents/Resources/ folder and references the files within the application's Mac OS X Property List (.PLIST) file.

One or more images can be stored within the same icon file, and are normally created from a PNG file. The format supports the following sizes: 16x16, 32x32, 48x48, 128x128, 256x256, 512x512, and 1024x1024 pixels.

ICNS files in Windows 10

How to Open an ICNS File

ICNS files can be opened with Apple Preview in macOS. Adobe Photoshop can open and build these files, too, but only if the IconBuilder plugin is installed.

Windows can open ICNS files with Inkscape or XnView MP (both also work on a Mac). IconWorkshop should support the Apple icon image format on Windows, too.

Considering that this is an image format, and several programs support opening it, it's possible you'll find that one program on your computer is configured by default to open ICNS files, but you'd prefer a different one do the job. If you're using Windows, and you'd like to change which program opens it by default, learn how to change file associations.

How to Convert an ICNS File

Windows users can use Inkscape or XnView MP to convert the ICNS file to basically any other image format. If you're on a Mac, Snap Converter can save the file as something else.

Regardless of the operating system you're on, you can also convert an ICNS file with an online converter, like CloudConvert or CoolUtils, the latter of which supports output formats like JPG, BMP, GIF, ICO, PNG, and PDF.

Alternatively, if you want to create an ICNS file from a PNG file, you can do so quickly on any OS with the MiConv website. Otherwise, I recommend using the Icon Composer tool that's part of the Apple Developer Tools software suite.

Still Can't Open It?

If your file isn't opening properly with the programs mentioned above, look at the file's extension again to confirm that you're reading it correctly. Some files might at first appear to use this extension, when really it's just spelled similarly.

ICS, INC (Total Commander settings file), and LCN (license file) are some examples. They are very similar looking, but have nothing to do with Apple icon files.

Your file might instead be a document preset file that uses the ICST file extension. If so, you need Adobe InCopy on your computer to view it.

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