How to back up your phone and computer with the 3-2-1 rule

The 3-2-1 backup rule is simple: keep three copies of anything you can’t afford to lose, on two different types of storage, with one copy off-site or in the cloud. For most people, that means letting your phone and computer back up to the cloud automatically, then copying everything to an external drive you keep at home. Here’s how to set that up on an iPhone, an Android phone, a Windows PC and a Mac.

What the 3-2-1 rule actually means

The rule is usually credited to photographer Peter Krogh, who described it in a book on managing digital photos. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) recommends it to everyone from home users to security professionals in its Data Backup Options paper. Here’s what each number means:

• 3 copies. The original on your device, plus two backups.
• 2 types of storage. For example, your phone plus the cloud, or your laptop’s internal drive plus an external drive. Different kinds of storage fail in different ways, so one problem is unlikely to wipe out both.
• 1 copy off-site. Fire, flood and burglary don’t care how many drives sit on your desk. A cloud backup, or a drive kept at a relative’s home or your office, covers that risk.

Why go to this much trouble? Data loss rarely gives a warning. A phone slips into a lake, a laptop gets stolen from a car, a drive stops working, or ransomware scrambles every file it can reach. CISA’s #StopRansomware Guide warns that many ransomware strains hunt for connected backups and encrypt or delete them too. That’s why it recommends offline backups that you test regularly.

One more thing to know: sync is not the same as backup. iCloud Drive, Google Drive and OneDrive keep your files the same on every device. That’s handy until you delete a folder by mistake and the deletion syncs everywhere. Sync services usually let you recover deleted files for a limited time, but a real backup keeps older copies that stay under your control.

Here’s what a 3-2-1 setup looks like with the tools built into your devices:

Device	Copy 1 (original)	Copy 2 (second type of storage)	Copy 3 (off-site)
iPhone	The phone	Encrypted backup on your Mac or PC	iCloud Backup
Android phone	The phone	Photos and files copied to your computer	Google backup and Google Photos
Windows PC	Internal drive	File History on an external drive	OneDrive through Windows Backup
Mac	Internal drive	Time Machine on an external drive	iCloud Drive or a cloud backup service

Step 1: Decide what to back up and how much space you need

Start with the things you can’t download again:

• Photos and videos, which usually take up the most space
• Documents, schoolwork and tax records
• Messages and contacts
• Recovery codes for important accounts. Our two-factor authentication guide explains why they matter, and a password manager is a safe place to keep them.

Apps and games you’ve bought can usually be downloaded again, so they matter less.

Next, check the storage section in your device’s settings to see how much space you’re using. For an external drive, Apple recommends a Time Machine disk with at least twice your Mac’s storage capacity, which is a sensible rule for any computer. Hard drives give you more space for the money, while portable SSDs are faster and cope better with knocks. Our SSD vs HDD guide walks through the trade-offs.

The free cloud allowances are small. Apple includes 5GB of iCloud storage, Google includes 15GB shared across your Google account, and a free Microsoft account comes with 5GB of OneDrive storage. If you have years of photos, you’ll probably need a paid plan for the cloud copy.

Step 2: Back up your phone

iPhone

For the cloud copy, turn on iCloud Backup:

1. Connect to Wi-Fi.
2. Open Settings, tap your name, then tap iCloud.
3. Tap iCloud Backup and turn on Back Up This iPhone.
4. Tap Back Up Now and stay on Wi-Fi until it finishes.

After that, your iPhone backs up on its own when it’s connected to power, locked and on Wi-Fi. Apple says it always encrypts iCloud backups.

For the second copy, back up to your computer:

1. Connect your iPhone to the computer with a cable.
2. On a Mac, select your iPhone in the Finder sidebar. On Windows, open the Apple Devices app, or iTunes if you don’t have it.
3. Click General (Summary in iTunes), then choose to back up all of the data on your iPhone to the computer.
4. Select Encrypt local backup and create a password.
5. Click Back Up Now.

Don’t skip encryption. Apple notes that encrypted backups include saved passwords, Wi-Fi settings, website history, Health data and call history, which unencrypted backups leave out.

Android

Menu names vary by phone maker, but on phones that use Google’s backup:

1. Open Settings, tap Google (or Google services), then All services.
2. Under Backup and restore, tap Backup.
3. Choose whether to include photos and videos, turn backup on, then tap Back up now.

Google’s backup covers apps and app data, call history, contacts, device settings and text messages. Photos and videos go through Google Photos. Google says a backup can take up to 24 hours to finish, and some data is encrypted with your screen lock, so use a PIN, pattern or password. Samsung and some other phone makers also offer their own backup services.

For the second copy, move your photos and videos to your computer. You can use a USB cable (choose file transfer when the phone asks) or download them from the Google Photos website. Once they’re on your computer, your computer backup protects them too.

Step 3: Back up your computer

Windows

For the local copy, use File History with an external drive:

1. Plug in the drive.
2. Open Control Panel, go to System and Security, and select Save backup copies of your files with File History.
3. Select Turn on. Use Select drive if Windows picks the wrong one.

File History saves copies of the files in your libraries, such as Documents, Pictures, Videos and Music, and keeps checking for changes. To get an older version back, right-click a folder in File Explorer and choose Restore previous versions.

For the cloud copy, open the Start menu, type “backup” and open Windows Backup. It syncs your Desktop, Documents, Pictures, Videos and Music folders to OneDrive and saves your settings, app list and Wi-Fi networks. You’ll need a personal Microsoft account, and it isn’t a full image of your PC. Because those folders sync, the File History copy is your safety net against accidental deletions.

Mac

For the local copy, use Time Machine:

1. Connect an external drive.
2. Choose Apple menu > System Settings, click General, then Time Machine.
3. Click Add Backup Disk, select the drive and click Set Up Disk.
4. Turn on Encrypt Backup and save the password somewhere safe.

Your Mac may offer to erase the drive first, so use an empty one. Time Machine keeps hourly backups for the past 24 hours, daily backups for the past month and weekly backups for older months. When the drive fills up, it deletes the oldest ones.

For the off-site copy, turn on the Desktop & Documents Folders option in your iCloud Drive settings, or use a cloud backup service that keeps older versions of your files. Like OneDrive, iCloud Drive syncs deletions too, so Time Machine is your safety net.

Step 4: Get one copy out of the house

A cloud backup already counts as your off-site copy. If you’d rather not pay for more cloud storage, or you have more files than fit, try these instead:

• Rotate two drives. Keep one at home and one at a trusted relative’s house or your workplace, and swap them every month or so. Time Machine can back up to more than one disk.
• Unplug between backups. A drive that’s always connected can be hit by ransomware or a power surge along with your computer.
• Encrypt anything that travels. A drive that leaves your house can get lost.

Step 5: Test your backups and keep them current

A backup only counts if you can restore from it. Every few months:

1. Check the date of the last successful backup on each device, in the same settings screen where you turned backups on.
2. Pick a random photo or document and restore it from each backup.
3. Watch for “storage full” warnings. Apple says your device won’t back up to iCloud once your iCloud storage runs out.
4. Run a manual backup before any big software update, repair or phone upgrade.

Also watch out for fake “your cloud storage is full” emails and texts. Check your storage in your device settings instead of clicking a link, and see our guide to spotting phishing for other warning signs.

The bottom line

You don’t need expensive gear to follow the 3-2-1 rule. Turn on the cloud backup built into your phone and computer, add an external drive with File History or Time Machine, and keep that drive unplugged when it’s not in use. Spend an hour setting it up, test it now and then, and a broken phone or dead laptop becomes a nuisance, not a disaster. For more ways to protect your devices and accounts, browse our cybersecurity coverage and the rest of the plain-English guides on RedAndWhiteMagz.com.