Convert ICO to ICNS

Windows ships icons as ICO; macOS uses ICNS. IconWorkshop reads both and converts in either direction from the same Windows workstation, so one set of artwork can cover both platforms.

How to convert an ICO to ICNS

Open the ICO in IconWorkshop - directly or from the built-in File Explorer.
Save or export it as a macOS icon. IconWorkshop maps the sizes into the ICNS family, up to 1024x1024.
Check the large 512 and 1024 sizes - macOS shows icons big in Finder and the Dock, so a missing large size is obvious.
Save the ICNS. The RSC and BIN macOS formats are available from the same export.

Either direction, one file or a folder

Converting a single asset? Open it and save for the other platform.
Moving a whole library? Use the File Explorer batch convert commands.
ICNS to ICO works exactly the same way - IconWorkshop reads macOS icons too.
You never leave Windows; only the size ceilings differ (1024 for macOS, 768 for Windows).

Common questions

Do I need a Mac to make ICNS files?

No. IconWorkshop is a Windows application that authors macOS icons. You convert ICO to ICNS, RSC, or BIN entirely on a Windows workstation.

What is the largest macOS icon size?

macOS icon containers go up to 1024x1024, which is larger than the 768x768 maximum Windows uses. IconWorkshop maps your sizes into the macOS family on export.

Can I convert a whole folder at once?

Yes. The File Explorer batch tools convert folders in either direction - ICO to ICNS or ICNS to ICO - in a single run.

Other conversions

SVG to ICO Vector master to a multi-size Windows icon. PNG to ICO Transparent PNG artwork to a Windows icon family. ICO to PNG Extract clean PNG sizes from an existing icon.

Build Cross-Platform Icons with IconWorkshop 6.97

Download the fully functional 30-day trial for Windows, or go straight to the perpetual license checkout.

Download 64-bit Download 32-bit Buy License

Windows 7, 8/8.1, 10, and 11. One license per developer, lifetime support, one year of updates included.