How to Back Up Your Computer: A Simple UK Guide
A clear guide to backing up a Windows or Mac computer using external drives and cloud storage, with the 3-2-1 idea, a simple routine and how to test restores.
Everyone knows they should back up, and a surprising number of people only do it after a loss. The good news is that a reasonable backup is easy to set up and then largely looks after itself.
What a backup actually is
A backup is a separate copy of your files that survives if the original is lost, stolen, damaged or encrypted by malware. Two things are not backups, despite common belief:
- A second folder on the same drive. If the drive fails, both go.
- Cloud syncing on its own. Services that mirror a folder will also mirror an accidental deletion, though many keep recovery windows.
The 3-2-1 idea in plain English
A well-known rule suggests:
- 3 copies of your important data (the original plus two others).
- 2 different types of storage, such as an external drive and cloud storage.
- 1 copy away from home, so fire, theft or flooding does not take everything.
You do not need to be rigid about it, but it gives you something to aim for.
What to back up
Start with what cannot be replaced:
- Photos and videos.
- Documents, tax and financial records.
- Work projects and creative files.
- Email archives and contacts if they are stored locally.
- Browser bookmarks and password manager exports, kept securely.
Operating system files and applications can be reinstalled, so they matter less unless you want a full system image.
Three practical setups
Simple: external drive
Buy an external drive larger than the data you want to keep. Use the built-in backup tools in Windows or macOS to run automatically when the drive is connected. Keep it unplugged when not in use, if you can, to reduce risk from malware.
Easier to forget: cloud backup
Cloud storage services can back up folders automatically. They suit people who do not want to remember to plug in a drive, and they give you an off-site copy. Be aware of storage limits, subscription costs and privacy. Our comparison of cloud storage versus an external hard drive goes through the trade-offs.
Belt and braces: both
Use the external drive for a complete local copy and the cloud for your most important folders. This approach meets the 3-2-1 idea with little effort.
Set a routine
- Automatic daily or weekly backups are best. Humans forget.
- Monthly check: open the backup and confirm recent files are there.
- Before major changes such as reinstalling the system, upgrading or sending the device for repair. See how to prepare for a tech support visit.
Test your restore
A backup you have never tried restoring is a hope, not a plan. Once or twice a year:
- Pick a few files from different folders and dates.
- Restore them to a temporary location.
- Open them and make sure they work.
If it fails, better to find out now.
Security
- Encrypt external drives holding sensitive information, using built-in tools.
- Use strong, unique passwords and two-factor authentication on cloud accounts. See two-factor authentication explained.
- Keep one backup disconnected so ransomware cannot reach it.
- Wipe or securely dispose of old backup drives. See disposing of old devices safely.
Getting help
If you would like someone to set up a backup, move your photos across or rescue files from an old machine, you can search Compito by postcode, compare ID-verified local providers and send a request. You receive an offer, accept and pay online, and message the provider to agree the plan. Browse tech support services.
A worked example: a family computer
A shared home computer holds 120GB of photos, 15GB of documents and the household's scanned paperwork. A sensible plan is a 1TB external drive with an automatic weekly backup, plus a cloud folder holding the photos and scanned documents that cannot be replaced. Setup takes an afternoon, the drive costs a modest one-off sum, and a cloud plan for a few hundred gigabytes is typically a few pounds a month. Once a quarter, one family member opens a few files from each place to check they are there.
Backup, sync and archive are different
| Term | What it does | Protects against |
|---|---|---|
| Backup | Keeps versions of files separately | Loss, theft, corruption, mistakes |
| Sync | Mirrors folders across devices | Convenience, not mistakes |
| Archive | Moves old files somewhere safe, often for good | Lack of space |
| System image | Copies the whole computer | A full rebuild after failure |
Many people have sync and believe they have backup. If a file can be deleted everywhere with one click, it is not a backup on its own.
Common mistakes
- Backing up to a drive that lives in the same bag as the laptop.
- Setting it up once and never checking that it still runs.
- Forgetting phones, tablets and the files in email attachments.
- Using a drive that is nearly full, so older versions are silently dropped.
- Keeping the only password for the cloud account in your head, or on the computer being backed up.
Edge cases
Shared households. Decide who owns what and where it goes, so one person tidying up does not delete another's folder.
Very large photo and video libraries. Prioritise originals and use a drive for the bulk, leaving the cloud for the most precious folders.
Older computers. A system that is struggling is exactly when you should back up. Copy files before updating, repairing or reinstalling.
Work laptops. Follow your employer's rules and do not copy company data to personal storage.
When to ask for help
If a drive is making clicking noises, if the computer will not start, or if you cannot find files you thought you had, stop using it and ask a technician before trying to repair anything yourself. See data recovery costs for what to expect.
Frequently asked questions
How big an external drive do I need?
Look at how much data you have and aim for at least twice that, so versions and growth fit. For most households, 1TB to 2TB is plenty.
Do I need to back up my phone too?
Yes. Photos, messages and app data are often the most personal files you own. Use the phone's built-in backup and check it is actually running.
How often should I back up?
Automatically and continuously if possible, or at least weekly. Consider how much work you could bear to lose.