Navigate to the official Apple Support Download Matrix and click the hyperlink.

: For specific updates or older versions, Apple Support provides individual update packages. System Requirements

Since Apple provides the installer as an .app file, you may need to convert it to a DMG for backup or transfer purposes.

Once you have downloaded the InstallMacOS.dmg or Install macOS High Sierra.app , you should create a bootable USB drive (at least 16GB) for a clean install.

Before installing, ensure that your target machine meets the necessary hardware criteria: Requirement 10.13.6 (Security Update 2020-006) Required Memory (RAM) Minimum 2 GB (4 GB recommended) Storage Capacity At least 14.3 GB of available space File System Shift Automatically transitions eligible SSDs to APFS Supported Mac Models MacBook: Late 2009 or newer MacBook Air / Pro: 2010 or newer Mac mini / iMac: Late 2009 or newer Mac Pro: 2010 or newer Creating a Bootable USB from the DMG File

You can still find High Sierra on the Mac App Store using a direct link, as it is often hidden from standard search results.

Set the format to and the scheme to GUID Partition Map . Create a Bootable USB : Open Terminal .

The link will trigger the to open a hidden preview page.

| Requirement | Details | |---|---| | | See list above | | Minimum OS | OS X 10.8 or newer | | RAM | At least 2 GB | | Free Storage for Upgrade | 14.3 GB | | USB Drive for Bootable Installer | 16 GB (formatted as Mac OS Extended) |

The .dmg (Disk Image) file is the complete, bootable installer for macOS. It functions as a "digital Swiss Army knife"—a portable, mountable container that packages the full operating system. It is essential if you want to:

If the official links are unavailable, the Internet Archive hosts a verified copy of the DMG for historical preservation. This is a legal and safe fallback if you are a genuine Mac owner.