A factory reset wipes your personal files, accounts, and settings — but not always the operating system
A factory reset erases the data you created and added to your device: photos, documents, emails, installed programs, saved passwords, and your customized settings. It returns the device to the state it left the manufacturer, with only the original operating system and pre-installed apps remaining.
What stays depends on the device type and reset method. On a phone or tablet, a factory reset typically removes everything except the OS. On a computer, you can choose whether to keep or erase the operating system itself — most factory resets on Windows or Mac preserve the OS but delete user files. Some devices also keep firmware and security software that runs below the operating system level.
The practical difference matters: if you're selling a phone, a factory reset is usually enough to protect your privacy. If you're troubleshooting a computer, you may need to decide whether you want to reinstall Windows or macOS afterward, or whether you're comfortable keeping the existing installation.
Key Takeaways
- A factory reset removes all your personal files, photos, emails, installed apps, and saved passwords from your device.
- The operating system (iOS, Android, Windows, or macOS) usually remains after a factory reset, though you can choose to erase it on computers.
- Phones and tablets typically have one reset option; computers usually offer a choice between keeping or removing the OS.
- Data removed by factory reset can sometimes be recovered with specialized software if the drive hasn't been overwritten, so physical destruction is the only way to may provide privacy.
What gets deleted on phones and tablets
On an iPhone, iPad, or Android phone, a factory reset removes every file you added to the device: photos, videos, messages, contacts, calendar events, notes, browsing history, saved passwords, and all installed apps except those that came with the device. Your email accounts are disconnected, and any data synced to cloud services (like iCloud or Google Drive) remains in those services but is no longer on the device itself.
The iOS or Android operating system stays on the phone. When you turn it on after the reset, you see the initial setup screen as though the device is brand new. You can then sign back into your accounts, reinstall your apps, and restore files from a backup if you made one before the reset.
One exception: if you've installed a custom ROM or modified the system files on an Android phone, a factory reset may not fully remove those changes. Standard factory resets on unmodified phones work as described above.
What gets deleted on Windows computers
Windows offers two reset paths, and they delete different amounts. The first option, "Reset this PC" with "Remove everything," erases all user files, installed programs, and personal settings — but keeps Windows itself. You'll need to sign in again and reinstall your programs, but the operating system is ready to use immediately after the reset.
The second option is a clean Windows installation, which removes Windows along with everything else. This requires installation media (a USB drive or DVD with Windows on it) and is more involved than a standard reset. Most people use the first option unless they're troubleshooting a corrupted Windows installation or want to switch to a different version of Windows.
Files stored in cloud services like OneDrive, Google Drive, or Dropbox are not affected by a Windows reset — they remain in those services. Local copies on your computer are deleted, but the originals stay in the cloud.
What gets deleted on Mac computers
On a Mac, "Erase and Reinstall" removes all user files, installed programs, and settings, then reinstalls macOS. The process is similar to Windows: your personal data is gone, but the operating system is fresh and ready to use. You can then sign in with your Apple ID and restore from a Time Machine backup if you have one.
A Mac reset also removes any third-party security software you installed, though built-in protections like Gatekeeper remain part of the OS. If you use FileVault encryption, the reset process handles decryption automatically — you don't need to decrypt the drive first.
Like Windows, files in iCloud, Google Drive, or other cloud services are not deleted from those services, only from your Mac's local storage.
What doesn't get deleted
The operating system itself — iOS, Android, Windows, or macOS — remains on the device after a factory reset. This is by design: the OS is what makes the device work, and removing it would leave you with an unusable machine.
Firmware, the low-level software that controls hardware functions, also stays. On phones, this includes the bootloader and radio firmware. On computers, it includes BIOS or UEFI settings. These are not user-facing and are not affected by a standard factory reset.
Pre-installed apps that came with the device typically remain as well. On an iPhone, this means apps like Settings, Camera, and Health. On an Android phone, it depends on the manufacturer — Samsung phones keep Samsung apps, for example. On Windows, built-in apps like Settings and File Explorer stay. On a Mac, apps like Finder and System Preferences remain.
Can deleted data be recovered after a factory reset?
Yes, sometimes. A factory reset does not physically destroy data — it marks the storage space as available for new files. Until the device writes new data over that space, recovery software can sometimes reconstruct deleted files. This is true on phones, tablets, and computers.
The longer you use the device after the reset, the less recoverable your old data becomes. If you reset a phone and immediately use it for weeks, the old files are likely overwritten and unrecoverable. If you reset and then turn the device off, the data may still be recoverable for months.
If privacy is your concern — for example, before selling a device — a factory reset is a reasonable first step for most situations. For highly sensitive data, physically destroying the storage drive is the only way to may provide nothing can be recovered.
Factory reset vs. signing out of accounts
Signing out of your email, social media, and cloud accounts is not the same as a factory reset. When you sign out, the apps remain on the device, and your files stay in cloud storage. A factory reset removes the apps and disconnects the accounts, but the files in cloud services are unaffected.
If you're giving a device to someone else, a factory reset is more thorough than signing out. Signing out alone leaves installed apps and settings in place, which the new user may not want. A factory reset gives them a clean slate.
If you're keeping the device and just want to disconnect an account, signing out is the right choice. You keep your apps and settings, and you can sign back in later if needed.
Frequently Asked Questions
Will a factory reset remove a virus or malware?
A factory reset removes most malware because it deletes all installed apps and user files where malware typically hides. However, some sophisticated malware can hide in firmware or system partitions and survive a standard reset. If you suspect a serious infection, a clean operating system installation (not just a reset) is more reliable.
Do I need to back up my files before a factory reset?
Yes, unless you're certain you don't need any of your current files. A factory reset is permanent — once it's done, files are gone unless you have a backup. Most phones and computers offer backup options (iCloud, Google Drive, Time Machine, Windows Backup) that you can restore from after the reset.
Will a factory reset remove my phone number or carrier information?
No. Your phone number and carrier information are stored on the SIM card, not on the phone's storage. A factory reset does not affect the SIM card. When you turn the phone back on, it will still be connected to your carrier and your phone number will remain the same.
Can I undo a factory reset?
Not directly. Once a factory reset completes, the deleted files are gone. You can restore from a backup if you made one before the reset, but you cannot undo the reset itself. This is why backing up before a reset is important.
How long does a factory reset take?
On a phone or tablet, a factory reset usually takes 5 to 15 minutes. On a computer, it can take 30 minutes to an hour, depending on how much data is being erased and how fast your storage drive is. The device will restart during the process and may appear to be frozen — this is normal.