You have three options once the is ready:
: You can download the disk image directly from the Apple Support page .
A USB flash drive with at least 16GB of storage (Note: This will be erased). The Install macOS Sierra.app in your Applications folder. Open Disk Utility . Select your USB drive. Click Erase . Format: Mac OS Extended (Journaled) . Scheme: GUID Partition Map . Name it: SierraInstaller . Use Terminal to Create the Bootable Drive: Open Terminal (Applications > Utilities). download macos 1012 sierra full
Tell me if you need help to confirm compatibility. macOS Sierra (10.12.6) Download - Apple Support Community
With the full installation file downloaded or your bootable USB created, you can choose between a standard upgrade or a fresh installation. Option A: Standard Direct Upgrade You have three options once the is ready:
The installation file is approximately 4.88GB .
Here is a detailed breakdown of the operating system. Open Disk Utility
Select your primary internal startup disk (usually Macintosh HD) as the destination.
If you'd like to create a for a clean install: Tell me if you need the Terminal command for macOS Sierra.
: You can find various version updates (like 10.12.6) on the Apple Support Downloads page, though these are typically "Combo" or "Delta" updates rather than the full base installer.