How to reset your iMac without losing data
Your iMac freezes. Programs crash. The system becomes slow. The logical step: reset. But then the doubts begin. What will happen to your files? Will you lose important settings? How do you prevent yourself from ending up with a dead iMac without your years of collected photos and documents?
Yet, resetting is often simpler than you think. The secret isn't complex software or expensive accessories , but the correct sequence of actions . Apple has made the process quite foolproof. Even without technical expertise, you can completely clean your iMac and keep all your data within an hour. All you need is an external drive and perhaps some time to listen to music through your AirPods while you wait. This step-by-step guide shows you exactly how.
Useful links
Preparing to reset
Resetting your iMac doesn't have to be stressful. With the right preparations, you can avoid problems and save all your important files. The most important thing: make a full backup before doing anything else.
Time Machine as a lifesaver
Time Machine remains the most reliable method for creating a complete backup. This built-in macOS feature saves not only your documents, but also system settings, applications, and even small details like desktop wallpapers. For a full backup, you'll need an external drive with sufficient storage space—at least twice the space your iMac uses.
Connect the external drive and open Time Machine through System Preferences. The first time you run it, the system will ask if you want to use this drive for backups. Confirm your choice and let the first backup complete. This can take several hours, depending on the amount of data, so plan ahead.
Log out of all accounts
Before you begin the actual reset, you must log out of all Apple services. This prevents problems with activation lock and ensures that personal data is completely deleted.
The most important accounts to log out of:
- iCloud : Go to System Preferences > Apple ID > Overview > Sign Out
- iTunes Store : Open the Music or TV app > Account > Authorizations > Deauthorize this computer
- iMessage : Open Messages > Preferences > iMessage > Sign Out
- FaceTime : Open FaceTime > Preferences > Settings > Sign Out
Also, don't forget to unpair any Bluetooth devices. This prevents confusion later when you want to use these devices with another Mac.
The actual reset process
Now comes the exciting part: actually wiping and reinstalling macOS. This process is done through macOS Recovery, a special mode that runs separately from your regular system.
Boot into recovery mode
Shut down your iMac completely. Press the power button and immediately hold down the Command (⌘) and R keys. Keep holding these until the Apple logo appears. You will now enter the macOS Recovery window.
Here you see four options:
- Restore from Time Machine backup
- Reinstall macOS
- Get online help
- Disk Utility
Wipe the hard drive
First, select Disk Utility. In the left panel, you'll see all your disks. Select your startup disk (usually called "Macintosh HD"). Click the "Erase" button in the toolbar.
When you erase you get a few options:
- Name : You can give the disk a new name or keep the old one
- Format : Choose APFS for modern iMacs (2016 or newer) or Mac OS Extended for older models
- Scheme : Leave this on GUID partition map
The wiping process usually only takes a few minutes. Afterward, close Disk Utility.
reinstall macOS
Back in the Recovery window, select "Reinstall macOS." The system will first check your internet connection and then download the latest version compatible with your iMac. This download can be quite large (around 12 GB), so a stable internet connection is essential.
Your iMac will restart several times during installation. This is normal. Let the process run completely uninterrupted. The total installation time varies from 30 minutes to several hours, depending on your internet speed and iMac model.
After installation: configuration
After successful installation, you'll be greeted by the Setup Assistant. Here you can choose whether to set it up as a new Mac or restore from a backup.
Restore from Time Machine
If you choose to restore from Time Machine, connect your backup drive. The assistant will automatically detect available backups. Select the most recent one (or a specific date if you want to revert to an older point). The restore process will copy all your data, apps, and settings back. This may take several hours.
Starting fresh
Want a clean slate? Skip the restore and set up your iMac as new. You'll need to manually reinstall your apps and transfer any data you want to keep. This gives you the chance to install only what you actually use.
Tips for a smooth process
A few practical tips will make the reset process more pleasant:
- Timing is everything : Don't start a reset right before a big deadline. Schedule plenty of time, preferably a weekend.
- Internet Connection : Make sure you have a stable, preferably wired, internet connection while downloading macOS
- Power Supply : Keep your iMac plugged in during the entire process
- Document settings : Take screenshots of important system settings that you want to restore later.
When is a reset useful?
Not every problem requires a complete reset. Sometimes, simply cleaning startup items or removing problematic software is sufficient. A reset is particularly useful for:
- Persistent system problems that resist other solutions
- Preparation for sale or transfer
- Upgrade to a brand new macOS version where you want to start fresh
- Suspected malware or other security issues
A refurbished iMac from Leapp is always delivered fully reset and clean, so you don't have to perform this process yourself upon purchase. This saves time and ensures everything has been done correctly.
Alternatives to a full reset
Sometimes a less drastic approach is enough. Try these options first:
- Safe Mode : Boot with Shift pressed to load only essential software
- NVRAM reset : Hold Option + Command + P + R during startup
- New User Account : Test if issues are account specific
- Disk Utility First Aid : Fix disk errors without erasing
These methods often resolve issues without having to recover all of your data.
Conclusion: reset without worries
So, resetting your iMac isn't magic at all. With a good Time Machine backup and this step-by-step plan, you'll be fine. The key is preparation: back up first, then erase .
If you'd rather start with a clean, professionally reset iMac , that's certainly possible. But for most users, follow these steps, take your time, and within a few hours your iMac will be running like new again. No hassle, no data loss.
