How to Restore Your iMac to Factory Settings

What restoring to factory settings actually does

Restoring your iMac to factory settings erases everything on the computer — all your files, programs, settings, and accounts — and reinstalls the original operating system that came with the machine. This is different from restarting or updating. When you restore, the hard drive becomes blank, and macOS reinstalls from scratch, as if the iMac just came out of the box.

People restore for different reasons: selling the computer, fixing serious software problems that won't go away, or starting fresh after years of accumulated clutter. The process takes 30 minutes to several hours depending on your internet speed and iMac model, and you cannot undo it once you start. Back up anything you want to keep before you begin.

Key Takeaways

Restoring to factory settings erases your entire hard drive and reinstalls macOS, so back up your files first using Time Machine or another method.
You need your Apple ID password and an internet connection to complete the restore, because macOS will ask you to sign in during setup.
The fastest method on modern iMacs (2011 and newer) is to restart while holding Command + R to enter Recovery Mode, then use Erase and Reinstall.
On older iMacs, you may need the original installation discs or a USB drive with macOS, depending on when the computer was made.
After the restore finishes, the iMac will restart and ask you to set up as a new computer, just like when it was new.

Back up your files before you start

Before you do anything, save copies of the files you want to keep. The restore process deletes everything, and there is no recovery once it begins. The easiest method is Time Machine, which is built into macOS and backs up automatically if you set it up beforehand.

If you have not used Time Machine, connect an external hard drive to your iMac, open System Preferences (or System Settings on newer versions), find Time Machine, and click "Select Backup Disk". Choose your external drive and let it run. If you do not have an external drive, you can copy important files to a cloud service like iCloud Drive, Google Drive, or Dropbox instead. Take the time to do this now — it takes minutes and saves hours of regret later.

Restart into Recovery Mode

Shut down your iMac completely. Turn it back on and when ready press and hold Command + R (the Command key and the R key together) until you see the Apple logo or a spinning globe. Keep holding until the macOS Utilities window appears. This is Recovery Mode, and it is where you control the restore process.

If you see a login screen instead of the Utilities window, you did not hold the keys early enough. Shut down again and try once more, pressing Command + R the moment you press the power button. On very new iMacs (2021 and later with Apple Silicon chips), you may see a startup options screen first — if so, select your iMac's name and click "Continue", then enter your password.

Erase the hard drive using Disk Utility

In the macOS Utilities window, click "Disk Utility" and then click "Continue". You will see a list of drives on the left side. Click the drive named "Macintosh HD" (or just "HD" on some models) — this is your main hard drive. Do not click anything else.

At the top of the window, click the "Erase" button. A dialog box will ask you to name the drive (you can leave it as "Macintosh HD") and choose a format. Leave the format as "APFS" if your iMac is from 2017 or newer, or "Mac OS Extended (Journaled)" if it is older. Click "Erase" and confirm. The process takes a few minutes. When it finishes, close Disk Utility and return to the Utilities window.

Reinstall macOS from Recovery Mode

Back in the macOS Utilities window, click "Reinstall macOS" (or "Reinstall OS X" on older versions) and click "Continue". The installer will ask you to agree to the terms — read them if you want, then click "Agree". Choose the erased "Macintosh HD" drive as the destination and click "Install".

The iMac will read macOS from Apple's servers and install it. This step requires an internet connection and can take 30 minutes to an hour depending on your speed. Do not turn off the iMac or unplug it during this time. When the installation finishes, the iMac will restart automatically.

Complete the setup process

After the restart, your iMac will show the setup screen, just like a brand-new computer. You will be asked to choose your language, connect to Wi-Fi, and sign in with your Apple ID. Enter the same Apple ID you used before — this lets you restore your apps and settings from iCloud if you want to.

You can choose to restore from a Time Machine backup at this point, which will put your files and programs back on the iMac. If you do this, the restore is not truly "factory" anymore — you are restoring your old setup. If you want a completely clean start, skip this step and set up as a new iMac. Either way, once you reach the desktop, the process is complete.

What to do if something goes wrong

If the iMac gets stuck during the erase or reinstall, force it to shut down by holding the power button for 10 seconds, then try again from the beginning. If you cannot get into Recovery Mode, restart and try Command + Option + R instead (this downloads a newer version of macOS from the internet, which sometimes works when Command + R does not).

If your iMac is very old (before 2011) or you do not have internet access, you may need the original installation discs that came with the computer, or you may need to create a bootable USB drive with macOS on it. These steps are more complex — if you are in this situation, contact Apple Support or a local repair shop, because the process differs by model and year.

Frequently Asked Questions

Do I need my Apple ID password to restore my iMac?

Yes. During setup after the restore, macOS will ask you to sign in with your Apple ID. If you forget the password, you can reset it at iforgot.apple.com before you start the restore. Write it down or keep it somewhere safe.

Can I restore my iMac without erasing the hard drive?

No. A true factory restore requires erasing everything. If you want to keep your files, use Time Machine to back them up first, then restore them after the process finishes. This gives you a clean operating system with your old files.

How long does the whole process take?

Typically 1 to 3 hours, depending on your internet speed and iMac model. The read and installation of macOS is the slowest part. A faster internet connection shortens this significantly.

What if I change my mind partway through?

If you have not clicked "Erase" yet, you can close Recovery Mode and restart normally — nothing has been deleted. Once you click "Erase" on the hard drive, the data is gone and you cannot undo it. This is why backing up first is so important.

Will restoring fix my iMac if it is running slowly or crashing?

Often yes, because a restore removes corrupted files and problematic programs. However, if the iMac has a hardware problem (like a failing hard drive), restoring will not fix it. If problems return after a clean restore, the issue is likely hardware, and you should have it checked by a technician.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.