For some older Macs this won't necessarily be the latest OS, such as MacOS Monterey, but instead MacOS Catalina, for example.

Your computer should then install the latest version of OS that it can install. Re-install MacOSX: click on ' Reinstall Mac OS X' > 'Continue'.Select the Mac OS Extended (Journaled), give a name to your disk and click on Erase.Select the startup disk and go to the Erase Tab.Select ' Disk Utility' and click on Continue. Choose Apple menu > Shut Down, press and hold the power button until Loading startup options appears, select Options, click Continue, then follow the onscreen instructions.Turn your Mac on, while holding the CMD + R keys down.Also, it is advised to make a time machine back up of your computer if possible before following the procedure. To reinstall your Mac's OS without an installation disc you need to firstly make sure that you keep your Mac turned on during the whole procedure, and that your Mac is connected to the internet. Back up Your Information It is highly recommended that you back up all information stored on your hard drive. In this article we will show you how to reinstall Mac OS without disc. Once macOS loads (You might need to select a language first.), click on Utilities > Disk Utility.

To do so, you need to press down Command + Option + Shift + R keys while turning on a Mac. Release when you see a list of bootable volumes, select the USB stick that you created, and click on the upward-pointing arrow. You can only reinstall the macOS that came with your Mac on Intel-based Macs. In the Recovery app window, select Reinstall for your macOS release, then click Continue. MacOS includes a recovery partition that allows you to easily erase all data on your Mac and reinstall your OS without an installation disc. Wait while the version of macOS installs on the drive. Intel-powered Mac: Press and hold Option (Alt) as you turn your Mac on. Reinstall your current version of macOS: Command-R.

How to reinstall macos from usb