Knowing how to back up your computer is one of the most practical things you can do with an afternoon. Hard drives fail. Ransomware encrypts files. Laptops get stolen. A current backup means any of those events is an inconvenience rather than a disaster. This guide walks through every method worth considering, from Windows built-in tools to Mac Time Machine to cloud services, so you can pick the approach that fits your setup and actually stick with it.
Why most people don't back up (and why that's a mistake)
The honest reason is that nothing has gone wrong yet. It's easy to defer a backup until there's a reason to panic, and by then it's too late. Data loss isn't a rare edge case. Drives have a finite lifespan, and even a solid-state drive can fail without warning. If you want to understand just how abruptly that can happen, the post on whether data can be recovered from a damaged or failed SSD is worth reading before you decide to keep putting this off.
The second reason people skip backups is complexity. It doesn't have to be complex. You need a copy of your data somewhere that isn't your main drive. Everything beyond that is refinement.
The 3-2-1 rule: the foundation of a solid backup strategy
Before touching any software, understand the 3-2-1 rule. Keep 3 copies of your data, on 2 different types of storage, with 1 copy stored off-site. In practice that looks like: your main computer, an external hard drive at home, and a cloud backup service. Any two of those three can fail at the same time and you still have a copy. That's the goal.
You don't have to implement all three today. Start with one. Add the others over time.
How to back up a Windows PC
Windows 11 includes two built-in backup tools. File History is for personal files. Windows Backup (via Settings) covers a broader system snapshot. Use both if you want complete coverage.
Using File History
Connect an external drive to your PC. Open Settings, go to System, then Storage, then Advanced storage settings, and select Backup options. Turn on File History and point it at your external drive. Windows will back up your Documents, Pictures, Music, Videos and Desktop folders automatically, on a schedule you set. The default is every hour, which is reasonable for most people.
File History keeps multiple versions of files, so you can restore a document from last Tuesday even if you've overwritten it three times since. That version history is one of the most useful features Windows offers and most people never switch it on.
Using Windows Backup for a full system image
Search for "Windows Backup" in the Start menu. This tool backs up your apps, settings, and credentials to a Microsoft account, so a fresh Windows install can restore your environment automatically. For a full system image (a complete snapshot of your drive), search instead for "Backup and Restore (Windows 7)" in the Control Panel. Despite the name, it still works on Windows 11 and creates a bootable image you can restore to a blank drive.
How to back up a Mac
Apple's Time Machine is the simplest backup tool available on any major platform. Connect an external drive, open System Settings, select General, then Time Machine, and add the drive as a backup disk. Time Machine will run automatically every hour, keeping hourly backups for the past 24 hours, daily backups for the past month, and weekly backups for all previous months (space permitting).
Time Machine backs up everything: your files, apps, settings, and system files. If your Mac fails completely, you can restore to a new Mac directly from a Time Machine backup during setup. It genuinely takes about 3 minutes to configure and then runs itself.
iCloud Drive as a supplement
Time Machine covers your whole system. iCloud Drive covers your most important files and syncs them across devices. Go to System Settings, click your Apple ID, then iCloud, and turn on iCloud Drive. Documents and Desktop folders can sync automatically. This isn't a substitute for Time Machine because it doesn't back up your apps or system, but it means your files are accessible from any device if your Mac is lost or stolen.
Cloud backup services worth using
A local backup protects you from drive failure. A cloud backup protects you from fire, theft, and anything else that can physically destroy both your computer and your external drive at the same time. The two most established services for personal and small business use are Backblaze and iDrive.
Backblaze Personal Backup costs around $9 USD per month and backs up unlimited data from one computer continuously. It runs in the background and you barely notice it. iDrive offers a family or business tier that covers multiple devices under one plan, which makes more sense if you're managing backups for a household or a small office. Both services keep deleted files for at least 30 days, so accidental deletions are recoverable.
Cloud backups have one practical drawback: the initial backup of a full drive can take days or weeks on a typical home internet connection. Start the first backup and leave it running. After that, only changed files are uploaded, which takes seconds.
External hard drives: what to know before you buy
Not all external drives are equally reliable. Spinning hard drives (HDD) are cheaper per gigabyte and suit large backups. Solid-state drives (SSD) are faster and more resistant to physical shock, which matters if you're carrying the drive around. For a backup drive that sits on a desk, a 2 TB or 4 TB HDD from a reputable brand is the most cost-effective choice.
Whatever you buy, check that the drive is formatted correctly for your operating system. Windows uses NTFS by default; Mac uses APFS or HFS+. If you want a drive that works on both without reformatting, use exFAT. Most drives ship formatted for Windows, so Mac users may need to reformat before first use. Disk Utility on Mac handles this in under a minute.
If you're weighing up the cost and reliability trade-offs between cloud and physical storage in more depth, the comparison of cloud backup vs external hard drives covers the real risks of each.
How often should you back up?
That depends on how much data you can afford to lose. If you create or edit files daily, back up daily. If your computer is mostly for browsing and streaming, weekly is probably fine. The practical answer for most people: set an automated backup and stop thinking about the schedule. File History on Windows and Time Machine on Mac both run automatically once configured. Cloud services run continuously. The only backup that actually protects you is one that runs without you having to remember it.
Testing your backup
A backup you've never tested is a backup you don't actually have. At least once every few months, restore a single file from your backup to confirm it works. For Time Machine, right-click any file in Finder and choose "Restore previous versions." For Windows File History, open the Backup options in Settings and click "Restore files from a current backup." For cloud services, log in to the web app and download a file. Five minutes of verification is worth it.
Backups also reduce your exposure to attacks like ransomware. If your files are encrypted by an attacker, a clean backup from before the infection means you restore and move on rather than pay. For a fuller picture of that threat, the guide on what ransomware is and how to protect against it explains how those attacks unfold and what stops them.
A quick-start checklist
- Buy a 2 TB external drive if you don't already own one.
- Connect it and enable File History (Windows) or Time Machine (Mac).
- Sign up for a cloud backup service (Backblaze or iDrive) and start the first backup.
- Verify one file restores successfully within the first week.
- Set a calendar reminder to check the backup status every 3 months.
That's the whole system. It costs less than $15 a month to run once it's set up, and it protects everything.