We may earn a commission when you buy through links on this page, at no extra cost to you.
The short answer
For backups, buy a mechanical hard drive: they are far cheaper per terabyte and speed barely matters for a scheduled backup. Buy at least twice the size of what you are backing up so you have version history. And buy two, because a single backup drive in the same room as the computer is not a backup plan.
Backup drives and working drives are different purchases. A working drive wants speed, which means an SSD. A backup drive wants capacity and reliability per pound, which still means a mechanical hard drive for most people. Buying the wrong type is how people end up with a 1TB SSD backing up 900GB of data with no room for history.
SSD or hard drive?
Hard drive
Cheaper per terabyte by a wide margin, available in large capacities, and perfectly fast enough for a backup that runs overnight or in the background. Vulnerable to drops while running. The right choice for a drive that sits on a desk or in a drawer.
SSD
Faster, silent, shock-resistant and much more expensive per terabyte. Worth it for a drive you carry daily, for working directly off, or for backing up a laptop quickly during a lunch break. Also worth considering if the drive will live in a bag, where a hard drive’s vulnerability to knocks matters.
For a typical household backup, a hard drive of twice the capacity costs less than an SSD of half. That extra capacity is what lets backup software keep multiple versions, which is often more valuable than the speed.
A backup is not a copy. A copy mirrors your current files, including the ones you accidentally deleted or the ones encrypted by ransomware. A backup keeps versions over time, so you can go back to last week. Any capacity you buy beyond your data size is what makes that possible.
Drives worth considering
WD 2TB Elements portable external hard drive
The unglamorous right answer for most people. It has no software, no encryption chip to fail, and no features to go wrong, which for a backup drive is exactly what you want. Two of these, one kept elsewhere, is a better backup strategy than one drive that cost twice as much.
Western Digital 5TB Elements portable external hard drive
Capacity is what buys you the ability to go back in time, and 5TB is comfortably more than most households generate. If you back up more than one computer to the same drive, this is the size to start at rather than 2TB.
Seagate 2TB portable hard drive, USB 3.0
A practical reason to mix brands: drives from the same batch can share the same defect. If you are buying two drives for a proper backup rotation, buying one of each manufacturer costs nothing extra and removes a small shared risk.
SanDisk 2TB Extreme portable SSD, USB-C, water and dust resistant
This is the right purchase for a drive that lives in a bag. Shock resistance genuinely matters for a portable drive, and the speed makes it usable as a working drive for photo and video editing rather than only as a backup target. You pay several times the price per terabyte for that.
WD 2TB My Passport portable external hard drive with backup software
Worth considering if you want a drive that prompts you to configure backups rather than leaving it to you. Be aware that hardware encryption ties the data to that drive’s controller, so if the enclosure fails, recovery is much harder. For most people, the operating system’s own backup tool plus a plain drive is the safer combination.
What we liked
- Hard drives give far more capacity per pound
- Extra capacity enables version history
- Portable SSDs survive being carried daily
- The operating system's own backup tools are free and good
What we didn't
- A single drive in the same room is not a real backup
- Hardware encryption complicates recovery
- Mechanical drives dislike being knocked while running
- Drives fail without warning, so rotation matters
Using it properly
Use the built-in backup tool
File History on Windows or Time Machine on macOS. Both keep versions automatically and both are more reliable than manual copying, which people stop doing after a month.
Buy two drives and rotate them
Keep one connected and one somewhere else, at a relative’s house or at work. Swap them monthly. This is what protects against fire, theft and ransomware.
Add a cloud copy for what matters most
Documents and photos in cloud storage plus local backups covers the realistic failure modes. Local backups alone do not survive a burglary.
Test a restore
Once, deliberately, restore a file from the backup. A backup nobody has ever restored from is a hope rather than a plan.
Eject before unplugging
Pulling a drive mid-write is the most common cause of corrupted backups.
Replace drives every few years
Mechanical drives have a finite life. A backup drive that is five years old should be retired rather than trusted.
How big should my backup drive be?
At least twice the amount of data you are backing up, and more if you want long version history. Capacity is what lets the software keep older versions rather than just the current state.
Is an SSD worth it for backups?
Only if the drive travels with you or you need backups to complete quickly. For a drive that sits on a desk and runs overnight, a hard drive gives you far more capacity for the money.
Do I still need a local backup if I use cloud storage?
Yes. Cloud sync propagates deletions and encryption, and restoring many terabytes over broadband is slow. The two protect against different things and work best together.
How long do external hard drives last?
Typically three to five years in regular use, and they can fail at any time without warning. That unpredictability is the argument for two drives rather than one bigger one.
Should I use the software that came with the drive?
Usually not. The operating system’s own backup tool is better maintained, keeps proper version history and does not tie your data to one manufacturer’s software.
The short version
Buy a mechanical drive with at least twice your data size, and buy two rather than one large one. Use the built-in backup tool rather than manual copying. Keep the second drive somewhere else and swap them monthly. Add cloud storage for the irreplaceable things, and restore one file deliberately so you know it works.
