How to Erase & Reinstall macOS from Recovery

This guide walks you through completely erasing your Mac’s startup disk and reinstalling macOS from Recovery Mode. This is the standard fix for serious system problems, preparing a Mac for sale, or starting fresh with a clean slate. You’ll need a stable internet connection and your Mac’s admin password (or the firmware password if one is set).

What You’ll Need

A Mac that can enter Recovery Mode (Intel or Apple Silicon).
A stable Wi-Fi or Ethernet connection (required to download macOS).
Your admin username and password.
Time: the entire process can take 1–3 hours depending on your internet speed.
Backups of any data you want to keep — this process permanently deletes everything.

Step-by-Step

Back up your data. Use Time Machine, a cloud service, or manually copy important files to an external drive. Once you erase the disk, there is no recovery.
Enter Recovery Mode.
- Apple Silicon (M1/M2/M3): Shut down your Mac, then press and hold the power button. Keep holding until you see “Loading startup options,” then click Options and click Continue.
- Intel Mac: Shut down, then press the power button and immediately hold Command (⌘) + R until you see the Apple logo or a spinning globe.
Wait for Recovery to load. You may be asked to select a user and enter your password. If you see a globe, macOS is downloading the recovery environment — this can take a few minutes.
Open Disk Utility. In the macOS Recovery window, select Disk Utility and click Continue.
Erase the startup disk.
- In Disk Utility, select your internal drive (usually named “Macintosh HD”) from the sidebar. If you see multiple volumes under it, select the top-level drive (the one with the manufacturer name or “APPLE SSD”).
- Click Erase in the toolbar.
- Set the Name to “Macintosh HD” (or anything you like).
- Set Format to APFS (for macOS 10.13 or later) or Mac OS Extended (Journaled) for older systems. On Apple Silicon, APFS is required.
- Set Scheme to GUID Partition Map (if available).
- Click Erase, then confirm. Wait for the process to finish, then click Done.
Quit Disk Utility. From the menu bar, choose Disk Utility > Quit Disk Utility (or press Command+Q).
Reinstall macOS. In the Recovery window, choose Reinstall macOS (or “Reinstall macOS Sonoma/Ventura/etc.”) and click Continue.
Select the disk. When prompted, choose the drive you just erased (likely “Macintosh HD”) and click Install.
Wait for installation. Your Mac will download the macOS installer and restart automatically. Do not interrupt this process. The screen may show a progress bar and a time estimate; it can take a while.
Set up your Mac. After installation, you’ll see the welcome screen. Go through the setup assistant, including creating a new admin account. If you’re selling the Mac, you can stop here — press Command+Q to shut down.

Common Mistakes

Erasing the wrong disk. Double-check that you’ve selected the internal drive, not an external backup drive. Look for the capacity and name.
Choosing the wrong format. On Apple Silicon, using Mac OS Extended instead of APFS can cause installation failures. Use APFS for modern macOS versions.
Erasing only a volume, not the whole disk. If you select “Macintosh HD – Data” instead of the physical drive, you’ll leave the system volume intact and the reinstall may fail.
Not backing up. The most common regret. Once erased, data is gone. Verify your backup is complete before proceeding.
Interrupting the installation. Closing the lid, unplugging power, or forcing a restart during installation can corrupt the system.

Tips

If you’re selling or giving away your Mac, after erasing and reinstalling, press Command+Q at the setup screen to leave it at “Hello.” This ensures the new owner gets a clean setup.
For Intel Macs, use Option+Command+R to boot into Internet Recovery, which can install the original macOS version that shipped with your Mac or a compatible newer one.
If Disk Utility shows multiple volumes, erase the parent disk (the top item) — this removes all volumes at once.
Keep your Mac plugged into power during the entire process, especially on laptops.
After installation, you can use Migration Assistant to restore from a Time Machine backup.

Troubleshooting

Recovery Mode won’t load. If holding Command+R does nothing, try Internet Recovery (Option+Command+R) or use a bootable USB installer. On Apple Silicon, ensure you’re holding the power button long enough (about 10 seconds).
Erase fails or is greyed out. If the Erase button is greyed out, you may have selected a volume instead of the disk. Also, try unmounting the disk first (select it and click Unmount in the toolbar). If it still fails, your drive may be failing — consider running First Aid first.
Installation says “macOS could not be installed on your computer.” This often happens if the disk isn’t formatted correctly. Go back to Disk Utility, erase again with APFS and GUID Partition Map, then retry.
Stuck on a globe or progress bar. This indicates a network issue. Check your Wi-Fi connection, or try using Ethernet. You can also restart and try a different recovery mode (e.g., Shift+Option+Command+R for the macOS that came with your Mac).
After installation, the Mac keeps restarting. This can be a hardware issue or a corrupt installer. Try erasing again and reinstalling. If it persists, contact Apple Support.
Forgot your admin password? You’ll need to reset it using your Apple ID (if enabled) or via Recovery’s Terminal (for older macOS versions). If that fails, you may need to use another Mac to create a bootable installer.

Frequently Asked Questions

Will this delete everything on my Mac?

Yes. Erasing the startup disk permanently deletes all files, apps, and settings on that disk. Make sure you have backups before proceeding.

Can I reinstall an older version of macOS?

On Intel Macs, you can use Shift+Option+Command+R to install the macOS version that originally shipped with your Mac (or the closest still available). On Apple Silicon, you can only install the latest compatible version.

Do I need an internet connection?

Yes, unless you have a bootable USB installer. Recovery Mode will download the macOS installer from Apple’s servers, which requires a network connection.

How long does the whole process take?

Erasing takes a few seconds. Downloading and installing macOS can take anywhere from 30 minutes to 2+ hours, depending on your internet speed and Mac model.

What if I don’t have a Time Machine backup?

You can still proceed, but you’ll lose all data. For the future, consider using Time Machine or a cloud backup service to avoid this situation.

Is this the same as “factory reset”?

Essentially yes. Erasing the disk and reinstalling macOS returns the system to a fresh state, just like when it left the factory, minus the original setup and any preinstalled apps.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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