How To Erase iMac Hard Drive | Apple Silicon & Intel Guide

Erase an iMac’s drive two ways: Disk Utility in Recovery for any model, or Erase All Content and Settings on newer macOS versions.

This guide shows how to erase iMac hard drive using either the Disk Utility Recovery method or the Erase All Content and Settings shortcut. Which option fits depends on your iMac’s chip — Apple silicon or Intel — and the macOS version it runs. Whether you’re selling your iMac, preparing for a trade-in, or starting fresh, erasing the drive resets the whole system.

Can You Erase An iMac Hard Drive Without Reinstalling macOS?

Not exactly. Erasing the startup disk removes macOS along with everything else, so the iMac won’t boot until you reinstall the operating system. There is one exception: the Erase All Content and Settings option on macOS Monterey or later acts like a factory reset, reinstalling the base system automatically. But the standard Disk Utility erase path requires a fresh macOS install afterward, which takes about 20 to 60 minutes depending on your connection speed.

Before Starting — Backup And Know Your Mac

Two checks prevent headaches. First, back up anything you want to keep — erasing removes all data from the startup disk with no undo. A Time Machine backup, a cloud sync, or a manual copy to an external drive covers this in under ten minutes.

Second, find out which chip your iMac runs. Open the Apple menu and click About This Mac. The processor line shows either an Apple silicon name (M1, M2, M3, or later) or an Intel processor. This determines the exact erase steps you’ll follow. Also note your macOS version under the same menu — if it’s Monterey or later, the faster Erase All Content and Settings path may be available.

Method 1 — Erase Via Disk Utility In macOS Recovery

The Disk Utility erase path works on every iMac regardless of chip or macOS version. The steps differ slightly between Apple silicon and Intel models.

On Apple silicon iMacs: Shut down the iMac completely. Press and hold the power button until “Loading startup options” appears, then click Options and Continue. When macOS Recovery loads, open Disk Utility from the Recovery utilities window. In the sidebar under Internal, select Macintosh HD. Click the Erase button, confirm the format is APFS, and click Erase Volume Group if that option appears — if not, click Erase instead. A confirmation message appears when it finishes. Quit Disk Utility. Per Apple’s official erase guide for Apple silicon Macs, an internet connection is required afterward for activation.

On Intel-based iMacs: Restart the iMac and immediately hold Command (⌘) + R until the Apple logo or a spinning globe appears — that means macOS Recovery loaded. Open Disk Utility, select Macintosh HD, click Erase, and choose APFS or Mac OS Extended (Journaled) based on what Disk Utility recommends. Click Erase Volume Group if available, or Erase if it is not. A success confirmation follows. Quit Disk Utility.

After erasing on either chip, you end up back in the Recovery menu ready to reinstall macOS.

Apple Silicon vs. Intel iMac — How The Erase Steps Compare

The table below breaks down the differences so you can follow the right flow for your machine.

Method 2 — Erase All Content And Settings (Newer Macs Only)

If your iMac runs macOS Monterey, Ventura, Sonoma, or later and you can still sign in to the desktop, the Erase All Content and Settings option is the quicker route. It erases user data and accounts while reinstalling the base OS in one operation — no separate Recovery session needed.

On macOS Ventura or Sonoma, open System Settings > General > Transfer or Reset, then click Erase All Content and Settings. On macOS Monterey, go to System Preferences > Erase All Content and Settings instead. The Mac restarts and walks through the out-of-box setup as if it were new.

This method only works when the iMac is signed in and the feature is supported on that model. If Erase All Content and Settings is missing or grayed out — or if the iMac won’t boot normally — fall back to the Disk Utility Recovery method from Method 1.

What To Do After Erasing — Reinstall macOS

After erasing via Disk Utility, the iMac has no operating system and can’t boot on its own. From the Recovery utilities window, click Reinstall macOS (the label matches your current OS version, such as “Reinstall macOS Sonoma”). Follow the onscreen prompts — the installer downloads macOS from Apple and installs it on the erased drive. The process takes 20 to 60 minutes depending on your internet speed. When it finishes, the iMac restarts into the setup assistant, where you can either set it up as new or restore from a backup.

On Apple silicon iMacs, an active internet connection is required during this step. On Intel iMacs, the installer uses the recovery partition, but a network connection is still needed on most recent macOS versions.

Common Mistakes That Trip People Up

Three errors cause most of the trouble. Trying to erase the startup disk from a normal desktop session instead of macOS Recovery — Intel Macs require Recovery for this, and the Erase option is disabled while the system is running. Selecting the wrong volume in Disk Utility — work only with Macintosh HD and ignore Macintosh HD – Data or any external drives, or the erase will fail or target the wrong disk. Using a file system other than APFS on Apple silicon — APFS is the only compatible format on those Macs, and choosing anything else produces an error. Avoiding these three keeps the process clean.

Recovery Erase vs. Erase All Content — Which Path Fits Your iMac

The table below helps you pick the right method at a glance.

For most iMacs running macOS Monterey or later that still boot normally, Erase All Content and Settings is the faster choice. For everything else — a non-booting machine, an Intel iMac on an older OS, or any situation where you need the full manual process — the Disk Utility Recovery method is the reliable fallback that works every time.