To back up your computer, follow the 3-2-1 rule: keep three copies of your data, on two different types of storage, with one copy stored somewhere else. In practice that means your computer, an external drive at home, and a cloud or offsite copy. Set it to run automatically and test a restore now and then.
What the 3-2-1 Rule Means
- 3 copies: the original on your computer plus two backups.
- 2 types of storage: for example, an internal drive and an external drive, so one kind of failure does not take everything.
- 1 copy offsite: in the cloud or at a relative’s house, so fire, theft or flooding at home cannot destroy every copy.
Each part answers a different risk. Two local copies protect against a dead drive. The offsite copy protects against a disaster. Ransomware and accidental deletion are the reason you want versions, not just one mirrored copy.
What Should You Back Up?
Start with files that cannot be replaced: photos, videos, documents, tax and work records, and anything you created. Programs can be reinstalled, so they matter less. If you want a complete image to restore a whole machine, many systems also offer full-system backup options.
Choosing Your Tools
| Method | How it works | Strength | Weakness |
|---|---|---|---|
| External drive with built-in tool | Windows File History or Mac Time Machine copies files on a schedule | Fast, cheap, private | Stays at home, drive can fail |
| Cloud backup service | Software uploads files to remote servers | Offsite and automatic | Ongoing cost; slow first upload |
| Cloud sync folder | Files in a synced folder appear on all devices | Easy for documents | Not a true backup if deletions sync |
| Network drive | Home storage box on your network | Handles several computers | Needs setup; still onsite |
Compare services in our cloud storage guide before you commit, and check current plans for pricing.
A Simple Setup in Five Steps
- Buy an external drive with comfortably more space than your computer’s used storage.
- Turn on the built-in tool. Windows has File History and Backup settings; macOS has Time Machine. Point either at the external drive and let it run.
- Add an offsite copy. Sign up for a cloud backup or use a second drive that you keep at another location and swap monthly.
- Automate it. A backup that depends on remembering will eventually be skipped.
- Test a restore. Open the backup and recover one file. This proves that it works before an emergency.
The first cloud upload of a large photo library can take days on a slow connection, so leave it running overnight. A stable home connection helps, and our guide to improving your home Wi-Fi signal has tips if uploads keep stalling.
Common Mistakes
Treating sync as backup
If a file is deleted or corrupted in a synced folder, the damage can copy to every device. Choose a service with version history or a recycle bin, and keep a separate backup.
Leaving the drive plugged in forever
Ransomware can encrypt connected drives too. Version history, or a drive you disconnect between backups, offers extra safety.
Never checking
Drives fill up and software stops silently. Look at the last-backup date monthly.
Security note: Encrypt external drives and offsite copies that hold sensitive files, and keep the password in a safe place. Our password manager guide covers storing it.
How Often Should You Back Up?
Ask how much work you could stand to lose. For most people automatic daily backups are right. If you edit files all day, hourly is better. Photographers and video editors should also copy new footage as soon as it is imported. For other housekeeping advice, see our technology guides.
What a Good Backup Looks Like Over Time
Backups are not a one-off job. Photos accumulate, projects change and drives wear out, so the setup you build today needs light maintenance. Plan to replace external drives every few years, before they fail rather than after, and keep an eye on free space so the newest files are always included.
It also helps to organise before you protect. Gather scattered files into a few clear folders, such as Documents, Photos and Work, so you know exactly what the backup covers. People often discover important files saved on the desktop or in a downloads folder that no tool was watching. Do the same for your phone: most phones can back up photos and settings automatically to their maker’s cloud, and that deserves a few minutes of attention too.
Finally, keep a short written note of where each copy lives and how to restore it. In a stressful moment, or if a family member has to help, clear instructions are worth far more than a clever setup nobody remembers.
Your Backup Plan for This Weekend
On Saturday, order or find an external drive and turn on your system’s built-in backup tool. On Sunday, choose an offsite option and begin the first upload. Put a reminder in your calendar for one month from now to open the backup and restore a single file. If that works, you have a real safety net.
Frequently asked questions
What is the 3-2-1 backup rule?
Keep three copies of your data, on two different types of storage, with one copy offsite. It protects against drive failure, theft, fire and other single-point problems.
Is cloud storage a backup?
Sync services can act as a copy, but deletions may sync everywhere. Use a service with version history or a dedicated backup, alongside local copies.
How often should I back up my computer?
Daily automatic backups suit most people. If you create important work throughout the day, back up more often.
How much storage do I need for backups?
Choose a drive with more capacity than the data on your computer, so it can hold several versions over time.
How do I know my backup works?
Restore a file from it. Checking the last-backup date monthly and testing a restore a few times a year catches problems early.
