How to Back Up Your Computer the Right Way

Hard drives fail. Laptops get stolen. Ransomware encrypts your files. Coffee spills on keyboards. The question is not whether you will lose data at some point, but whether you will have a copy when it happens.

Most people know they should back up their computer. Most people do not actually do it until after they lose something important. Setting up a proper backup takes about 30 minutes and then runs automatically from that point forward.

Here is how to do it right.

The 3-2-1 Rule

The gold standard for backups is the 3-2-1 rule: keep three copies of your data, on two different types of storage, with one copy stored off-site. This sounds excessive until you consider the scenarios it protects against.

Three copies means your original data plus two backups. If one backup fails or becomes corrupted, you still have another.

Two different storage types means combining, for example, an external hard drive with a cloud backup. If a power surge fries your computer and the external drive plugged into it, the cloud copy is unaffected. One off-site copy protects against physical disasters like fire, flood, or theft that could destroy everything in one location.

You do not need to follow this rule perfectly. Any backup is better than no backup.

But the closer you get to 3-2-1, the more resilient your data becomes against different types of loss.

Local Backups with an External Drive

An external hard drive connected to your computer via USB is the simplest form of backup. A 2 TB external drive costs about $60 to $80 and holds more than enough data for most people's computers.

On Windows, use the built-in File History feature.

Go to Settings, then Update and Security, then Backup. Connect your external drive and click "Add a drive." Select the drive and turn on "Automatically back up my files." File History continuously backs up your personal files (documents, photos, music, desktop) and lets you restore previous versions of individual files.

On Mac, use Time Machine. Connect your external drive and macOS will ask if you want to use it for Time Machine. Click "Use as Backup Disk." Time Machine creates hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for previous months. It manages the space automatically by deleting the oldest backups when the drive fills up.

Both File History and Time Machine run automatically once configured.

You do not need to remember to back up. Just leave the external drive connected and the software handles the rest.

Cloud Backups

Cloud backup services automatically upload your files to remote servers over the internet. The main advantage over local backups is off-site protection. If your house burns down, your cloud backup is safe in a data center somewhere else.

For backing up specific folders, services like Google Drive, OneDrive, and Dropbox sync selected folders to the cloud.

Google offers 15 GB free, OneDrive offers 5 GB free, and Dropbox offers 2 GB free. Paid plans with 1 to 2 TB of storage typically cost $10 to $12 per month.

For a complete computer backup that includes your operating system, applications, and all files, dedicated backup services like Backblaze ($7 per month for unlimited storage) or Carbonite (starting around $6 per month) are designed to run continuously in the background and back up everything on your computer without you selecting specific folders.

Cloud backups are slower than local backups because they depend on your internet upload speed.

The initial backup of a full computer can take days or even weeks on a slow connection. After the initial backup, incremental backups only upload files that have changed, which is much faster.

What to Back Up

At minimum, back up anything you cannot replace: personal photos, documents, financial records, creative work, and important emails. These are the files that have actual sentimental or practical value.

Applications and operating system files can usually be re-downloaded and reinstalled. Backing them up is convenient because it speeds up recovery after a failure, but it is not essential. If you are short on backup space, prioritize irreplaceable personal files over software.

Testing Your Backups

A backup that you have never tested is a backup that might not work when you need it. Once you have set up your backup system, try restoring a file. On Windows, right-click a file, choose "Restore previous versions," and verify that the backup versions are there. On Mac, open Time Machine and browse to a specific file and date to confirm the backup is working.

Do this test once every few months. It takes two minutes and gives you confidence that your backup is actually functioning. Discovering a broken backup when you desperately need it is a particularly painful experience.

A Simple Setup That Covers Most People

Buy a 2 TB external hard drive and set up File History (Windows) or Time Machine (Mac) for local backup. Sign up for Backblaze or a similar cloud backup service for off-site protection. That gives you a local backup for fast restores and a cloud backup for disaster protection. Total cost: about $70 for the drive plus $7 per month for cloud storage. Total setup time: about 30 minutes. And from that point forward, your data is protected automatically.