The simplest way to back up everything on your computer

The fastest method is to use the backup tool built into your operating system. Windows has File History; Mac has Time Machine. Both work the same way: you plug in an external hard drive, turn on the backup feature, and the system copies everything automatically from that point forward. You do not have to choose which files to save — the computer saves them all.

An external hard drive costs between $50 and $150 depending on storage size, and you only buy it once. Plug it in weekly or leave it connected all the time. The backup runs in the background without slowing down your work. When something goes wrong — a virus, accidental deletion, or hardware failure — you can restore your entire computer to the way it was on any date the backup ran.

This method backs up your operating system, programs, settings, and files in one step. You do not need to understand what to save or where it lives. Everything is covered.

Key Takeaways

  • Windows File History and Mac Time Machine are built-in tools that automatically back up your entire computer to an external hard drive without any setup beyond plugging it in.
  • An external hard drive should be at least as large as your computer's storage — a 1 or 2 terabyte drive works for most people and costs $50 to $150.
  • Backups run automatically in the background once you turn them on, so you do not have to remember to do anything after the first setup.
  • When you restore from a backup, your computer returns to exactly how it was on the date you choose, including all programs and settings.
  • Keep the external drive unplugged most of the time to protect it from power surges and the same disasters that could damage your computer.

Setting up File History on Windows

Plug the external hard drive into a USB port on your computer. Wait 10 seconds for Windows to recognize it. Then open Settings by pressing the Windows key and typing "settings" — the Settings app will appear at the top of the results.

In Settings, click System on the left side, then scroll down and click About. At the bottom of the About page, click Advanced system settings. A window titled System Properties will open. Click the System Protection tab at the top, then click Configure. Select "Restore system settings and previous versions of files" and click OK. This turns on File History.

Now open Settings again and search for "backup settings." Click Backup options. Under "Back up using File History," toggle the switch to On. Windows will ask you to choose a drive — select your external hard drive from the list. File History will now run automatically every hour when the drive is plugged in.

Setting up Time Machine on Mac

Plug the external hard drive into a USB port. A dialog box will appear asking if you want to use this drive for Time Machine backups. Click Use as Backup Disk. If the dialog does not appear, open System Settings, click General on the left, then click Time Machine, and toggle it On.

Mac will ask you to select a backup drive. Choose your external hard drive. You can also click Options to exclude folders you do not want backed up — for example, if you have a folder of video files that are backed up elsewhere, you can skip them to save space on the drive.

Time Machine will run automatically every hour when the drive is connected. You can also click the Time Machine icon in the menu bar at the top right of the screen and select Back Up Now to start a backup when ready.

Choosing the right external hard drive

The drive needs to be at least as large as your computer's storage. To find your storage size, open File Explorer on Windows and right-click This PC, then click Properties. On Mac, click the Apple menu, select About This Mac, then click Storage. Write down the number you see.

Buy an external drive that is at least that size, or larger. A 1 terabyte drive holds about 1,000 gigabytes and works for most computers. A 2 terabyte drive gives you room for multiple backups over time, which is useful because older backups let you recover files from weeks or months ago. Brands like Western Digital, Seagate, and LaCie are widely available and reliable.

Do not buy a drive that is only slightly larger than your current storage. As you add files over time, you need room for the backup to grow. A good rule is to buy a drive at least twice the size of your current storage.

Where to keep your backup drive

Store the external drive in a different location from your computer when you are not actively backing up. If your computer is damaged by fire, flood, or theft, a backup drive sitting next to it will be damaged too. Keep it in another room, in a safe, or at a friend's house.

Plug it in once a week for a few hours to let the backup run, then unplug it and store it away. This schedule protects the drive from power surges and electrical damage that could affect both your computer and the backup at the same time. It also protects the backup from the same malware or ransomware that might infect your computer.

If you leave the drive plugged in all the time, set a reminder to unplug it weekly and store it elsewhere. The small effort of moving the drive is worth the protection it gives you.

Restoring your computer from a backup

On Windows, plug in the external drive. Open Settings, search for "recovery options," and click Recovery options. Under Reset this PC, click get your free guide. Choose Keep my files or Remove everything depending on whether you want to keep your current files or start fresh. Windows will restore your computer to a previous state using the backup.

On Mac, restart your computer and hold Command + R while it boots. This opens Recovery Mode. Click Restore from Time Machine Backup. Select your external drive and choose the backup date you want to restore from. Your Mac will return to exactly how it was on that date.

Restoring takes time — usually 30 minutes to several hours depending on how much data you have. Do not turn off your computer during the process. When it finishes, your computer will restart and everything will be back the way it was.

What happens if your backup drive fails

External hard drives can fail without warning. If your backup drive stops working, you have lost the backup but not your original computer — your files are still on your computer's internal drive. You can buy a new external drive and start backing up again when ready.

This is why many people keep two external drives and rotate them. Back up to Drive A for a month, then switch to Drive B while Drive A sits in storage. If one drive fails, you still have backups from the other one. This costs more but gives you protection against drive failure.

If you want backup protection that does not depend on a physical drive you own, you can also use cloud backup services like OneDrive, Google Drive, or iCloud. These services store your files on company servers instead of a drive in your home. They cost money each month but protect against both computer failure and physical disasters.

Frequently Asked Questions

Do I need to do anything after I turn on File History or Time Machine?

No. Once you turn it on and select your external drive, the backup runs automatically every hour without any action from you. You only need to plug in the drive periodically so the backup can run. You do not have to remember to start it or check on it.

Can I use the same external drive to back up two different computers?

Yes, but each computer needs its own folder on the drive. When you plug the drive into a second computer and turn on File History or Time Machine, the system will create a separate backup folder. Both computers can back up to the same physical drive as long as the drive is large enough to hold both backups.

What if I accidentally delete a file after the backup runs?

Plug in your external drive. On Windows, open File Explorer, right-click the folder where the file was, and select Restore previous versions. Choose the backup date before you deleted the file. On Mac, open the folder, click the Time Machine icon in the menu bar, and browse to the date before the deletion. Your file will be restored.

How often should I plug in my backup drive?

Once a week is a good schedule for most people. This means you never lose more than a week of work if something goes wrong. If you create important files every day, plug it in more often. If you rarely change anything on your computer, once a month is acceptable.

Can I back up to a network drive instead of an external hard drive?

On Mac, yes — Time Machine works with network drives. On Windows, File History works with network drives too, though external drives are more reliable. Network backups depend on your internet connection and the other computer or device staying on and connected, so external drives are simpler for most people.