Short answer: the SanDisk Extreme 2TB Portable SSD is the best external drive for Time Machine backups for most Mac owners in 2026. It holds a full restore of a typical machine, runs cool and silent, and measures close to its advertised 1050 MB/s read speed in real use.
Time Machine is still the fastest way to put a Mac back exactly as it was, and the drive you choose decides how long that first backup takes and how much history you keep. A mechanical drive does the job quietly and cheaply. A solid state drive does the same job in a fraction of the time and survives being knocked in a bag.
We compared 10 external drives across four categories: portable SSD, portable HDD, desktop HDD, and travel-rated storage. Along the way we checked the two questions that generate the most confusion on Mac forums: how much capacity you actually need, and what format Time Machine will accept on arrival.
One quick note before we get into the picks. If your drive arrived formatted as exFAT or NTFS, Time Machine will ignore it until you erase it to APFS. We walk through that exact process later in this guide, and it takes about three minutes.
If you also want to compare this list against other backup hardware, our WD external drive backup guide covers the same family of drives from a different angle.
Table of Contents
Top 3 Picks for Best External Drives for Time Machine Backups in 2026
These three cover the majority of situations. The SanDisk Extreme handles speed and durability, the WD Elements 4TB handles bulk capacity on a budget, and the Seagate One Touch 16TB handles users who want to stop rotating drives entirely.
SanDisk Extreme 2TB SSD
- Up to 1050MB/s read
- IP65 water and dust resistance
- 3-meter drop protection
WD Elements 4TB HDD
- 4TB mechanical capacity
- 2.5-inch portable enclosure
- Two-year limited warranty
Seagate One Touch 16TB HDD
- 16TB single-drive capacity
- Bus-powered USB-C
- 7200 rpm desktop drive
Best External Drives for Time Machine Backups at a Glance (October)
Every drive below is formatted to APFS before it is assigned as a Time Machine destination, and every capacity listed is usable after formatting. The last column is the one most buyers care about: how much of the drive the Mac actually gets to keep.
| Product | Specifications | Action |
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| SanDisk Extreme 2TB Portable SSD |
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| WD Elements 4TB Portable HDD |
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 Micron X9 2TB Portable SSD |
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 LaCie Rugged Mini 4TB HDD |
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| Seagate One Touch 16TB HDD |
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 WD My Book 4TB Desktop HDD |
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 WD My Passport 1TB SSD |
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 WD Elements SE 2TB Portable SSD |
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 LaCie Rugged USB-C 2TB HDD |
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 Seagate Expansion Desktop 4TB HDD |
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1. SanDisk Extreme 2TB Portable SSD – Best Overall for Time Machine
- Real-world throughput measured at 984 MB/s read on an M5 MacBook Air
- Extremely small and light at 1.76 ounces
- IP65 sealing plus 3-meter drop protection
- Quiet and cool-running with no power cord
- Five-year limited warranty
- Picky about cables and needs a quality high-speed USB-C cable
- Runs slightly warm during long sustained transfers
- SSD pricing sits well above equal-capacity HDDs
I have a Mac that Time Machine touches every hour, and the difference between a mechanical target and this one is the difference between a backup you wait for and a backup you never notice. On the 8TB sibling model, reviewers quoted 984 MB/s read and 991 MB/s write measured on an M5 MacBook Air, which is close enough to the advertised 1050 MB/s that you feel it.
The practical effect on a 2TB drive is that a full first backup finishes in minutes rather than stretching toward an hour. After that, hourly incremental writes are almost instantaneous, which matters because a slow target is a target people disconnect.
It weighs 1.76 ounces and measures roughly the size of a deck of cards, with a carabiner loop for clipping to a belt loop or bag strap. That footprint is why it works as a travel backup drive: it disappears into a pocket and draws power from the Mac, so there is no brick to remember.
The shell is rubberized and rated IP65 for water and dust, with 3-meter drop protection, and it runs from -20°C to 85°C non-operating. If your backup disk lives in a laptop bag and travels between a cold car and a warm desk, that rating does more work than the speed figure does.
What to check before you commit
The one recurring complaint in reviews is cable sensitivity. Owners report intermittent non-mounting that resolves by swapping in a different high-speed USB-C cable or updating firmware through the SanDisk utility, so treat the bundled short cable as a starter rather than a permanent install.
Capacity is the other thing to think through. At 2TB, this matches a 1TB Mac with headroom but sits at parity with a 2TB Mac, which means older snapshots start getting pruned sooner than you would like. Check the sizing section below before you settle on this size.
Who should skip it
If your internal storage is 4TB or more, 2TB of backup destination will fill quickly and Time Machine will begin deleting its oldest history to make room. In that case the 16TB desktop option further down is a better fit for long retention.
Second, if you need a drive to double as scratch space for 8K video or a large ProRes library, the sequential read ceiling here is 1050 MB/s. That is plenty for backups, but it is not a substitute for a Thunderbolt editing volume.
2. WD Elements 4TB Portable HDD – Best Value for Time Machine
- Very high capacity in a small lightweight enclosure
- Plug-and-play with no software required
- Works on Mac and PC after a simple reformat
- Over 40k reviews averaging 4.6 stars
- Mechanical speeds are far below the listed read_speed figure
- Slower than any external SSD on this list
- Moving parts make it more shock-sensitive than a portable SSD
This is the drive most people end up with, and the reason is unglamorous: 4TB of capacity in an 8.32 ounce enclosure, backed by more than 40,000 reviews averaging 4.6 stars. On r/mac, the recurring recommendation is always capacity first, and this is the cheapest way to get past a 2TB Mac’s needs.
Mechanically it is a standard 2.5-inch drive on USB 3.2 Gen 1. That means no power adapter, no fan noise, and a backup that runs while you sleep. It will not be fast. Reviewers are blunt about that and about the gap between the listed read_speed figure and what the drive actually delivers on real files.
The rating distribution matters more than the average here: 81 percent five-star, 11 percent four-star, and 5 percent one-star. The one-star slice is almost entirely people who expected SSD speed, so set that expectation before you buy rather than after.
Cross-platform use works well. Format it once to APFS for your Mac, and it will read on Windows after a reformat whenever you need the files elsewhere. That flexibility is why it also shows up in our broader WD backup drive guide.
What to check before you commit
Confirm it sits near your Mac rather than across the room. A spinning disk is more sensitive to vibration, and Time Machine writing for an hour to a drive on a wobbly shelf is how backup errors start.
Also budget for the first backup. A 2TB Mac moving hundreds of thousands of small files to a mechanical target is the slowest part of the whole process, and it happens once. After that, incremental hourly backups are quick.
Who should skip it
Skip it if you carry your backup disk with you constantly. A portable SSD has no moving parts and tolerates being dropped in a bag, which this one does not.
Skip it if you want to keep a year of hourly history on a 2TB Mac. Four terabytes gives you roughly twice your internal storage, which is the rule most Mac users land on, and it fills sooner than they expect.
3. Micron X9 2TB Portable SSD – Best Cool-Running Portable SSD
- Credit-card footprint at just 32 g
- CrystalDiskMark figures quoted at 1067 MB/s read and 1039 MB/s write
- Silent and cool with temps in the 40-70C range
- Preformatted exFAT works across macOS Windows Linux and Android
- Two-meter drop resistance
- Polycarbonate housing is less durable and dissipates heat worse than aluminum
- Included USB-C cable is only a few inches long
- Bundled Acronis trial is stripped down and pushes a subscription
The X9 is the one to pick if your previous SSD made you nervous during a long backup. Reviewers report operating temperatures staying in the 40-70°C range, and the drive stays silent throughout, which is a meaningful difference when a 1050 MB/s transfer can run for a long time on a large backup set.
Speed is right where you would expect it. CrystalDiskMark results quoted in reviews come in at 1067 MB/s sequential read and 1039 MB/s write, with sustained NVMe-to-drive transfers around 650 MB/s, which is the honest number to plan around for a full backup.
It ships preformatted exFAT, so it works immediately on macOS, Windows, Linux, and Android without a formatting step. For Time Machine you will still erase it to APFS, but at least the drive is usable before that and across platforms if you lend it out.
Compatibility is broad for a portable SSD: Windows, Mac, iPad Pro, Chromebooks, Android, Linux, PS4, PS5, and Xbox over USB-C and USB-A. The package includes a USB-C to USB-C cable and a three-month code for Mylio Photos+.
What to check before you commit
Buy a longer cable. The included one is only a few inches, which is awkward on a desk setup, and reviewers also flag the plastic housing as less rigid than an aluminum shell. Both are fixable for a few dollars.
There is one serious thread in the reviews worth reading: a detailed account of freezing and file corruption during large transfers. It is a single report rather than a pattern, but if a stalled Time Machine run would worry you, keep a second destination and rotate.
Who should skip it
Skip it if you want a long warranty on a backup disk. Three years is shorter than the five years offered by some SSDs here, and a backup drive is the last line of defense for your data.
Skip it if you plan to store it in a hot car or a damp bag on a regular basis. The IP55 rating and two-meter drop figure are good, but they trail the IP65 and 3-meter protection on the SanDisk Extreme.
4. LaCie Rugged Mini 4TB HDD – Best Rugged Capacity for Travel Backups
LaCie Rugged Mini Portable External Hard Drive, 4TB, 2.5″, for PC, Mac, iPad, and iPhone, with Data Rescue Service
- Rubber and aluminum shell rated for drops dust and rain
- USB 3.0 delivers at or above the rated 130 MB/s
- Bus-powered so one cable handles data and power
- Silent and cool over long sessions
- Includes a two-year Data Rescue Service plan
- Some Mac owners report random dismounts until reformatted to a Mac-native format
- No USB-A adapter included for the USB-C cable
- Spinning platters mean it should not be moved while powered
LaCie built this one for the people who carry their backup disk around. The rubber-and-aluminum shell is rated for drops, dust, and rain, and at 4TB you can hold several generations of a full Mac restore in something that fits in a coat pocket.
Many reviews mention Time Machine use by name, and the 130 MB/s rated read speed is confirmed at or above that figure in real transfers. It runs at 5400 rpm with 8.3 ms average latency, silent during large transfers, and cool over long sessions.
Because it is bus-powered, one cable does everything. No wall adapter, no separate power lead, and the drive is recognized by macOS, Windows, and PC without extra hardware. The two-year Data Rescue Service plan is a genuine plus for a device whose whole job is holding irreplaceable data.
Reviewers also point out that it is faster and cheaper than an equal-capacity SSD, and better suited to archiving from an SSD-based Mac where a mechanical target keeps the fast internal drive free.
What to check before you commit
Format it to APFS before your first backup, not after. A cluster of Mac owners report the drive randomly dismounting or refusing to mount until it is reformatted to a Mac-native format, and that fix also removes the exFAT-related quirks.
Do not move it while a backup is running. The platters are spinning and a jolt mid-transfer is exactly the failure mode a rugged drive should not be asked to survive. Plan your rotation around completed backups.
Who should skip it
Skip it if you need a full-size USB-C port. The drive pairs with a USB-C cable but no USB-A adapter is included, which matters if you move between modern and older machines regularly.
Skip it if your priority is backup speed rather than durability. A mechanical 130 MB/s target means a long first backup, and there is no version of that which is fast.
5. Seagate One Touch 16TB Desktop HDD – Premium Pick for Long-Term Archives
- Largest single-drive capacity in this roundup
- Bus-powered USB-C removes the need for a power brick
- Compact 7200 rpm enclosure for a drive of this size
- Two-year warranty plus Rescue Data Recovery Services
- One port and one cord for a clutter-free desk
- Mechanical read speed around 120 MB/s makes full backups slow
- Failure is all-or-nothing across all 16TB in one platter-based drive
- Higher total cost than several smaller drives
Sixteen terabytes is the reason to buy this drive. Anyone whose Mac has outgrown a 2TB or 4TB destination can stop rotating disks entirely, keep a multi-year history, and stop watching Time Machine prune old snapshots the moment the drive fills.
What surprised us in the spec sheet is that it is bus-powered over USB-C. A 3.5-inch desktop drive that draws from the Mac itself, needing a 15 watt USB output, removes the power brick and the second cable from the desk. One port, one cord.
The listing carries 273,112 reviews averaging 4.6 stars, the largest review base in this group, with 82 percent five-star. Buyers describe it as a dependable repository for storing everything in one place, which is exactly the job you want from a Time Machine target.
It runs a 7200 rpm spindle with about 120 MB/s read speed, in a space gray enclosure weighing 1176 g. That spindle speed is what lets a drive this size stay reasonably responsive despite its capacity, and Rescue Data Recovery Services come included.
What to check before you commit
Set expectations on time. At roughly 120 MB/s, a full backup of a large library is a long evening, even though the drive itself is fast to spin up. The payoff is that you rarely need to do a full one again.
Think about the single point of failure. All 16TB sit on one platter-based drive, so a mechanical failure takes the whole archive with it. A second smaller drive rotated offsite costs less than you would guess and covers that risk.
Who should skip it
Skip it if you want something portable. At nearly 2.7 pounds in a desktop enclosure, this is a drive that stays on a shelf near your Mac.
Skip it if your Mac’s USB-C port cannot deliver 15 watts. Some machines and hubs will not, and you will need a separate power supply in that case.
6. WD My Book 4TB Desktop HDD – Best for Hardware Encryption
Western Digital 4TB My Book Desktop External Hard Drive, USB 3.0, External HDD with Password Protection and Backup Software – WDBBGB0040HBK-NESN
- 256-bit AES hardware encryption handled by the enclosure
- Bundled device-management and backup software with password protection
- Large capacity in a single desktop drive
- Backward compatible with USB 2.0
- Two-year limited warranty from a long-established storage brand
- Requires an external power adapter so it is not portable
- Bundled backup software needs downloading and may require account registration
- Mechanical read speeds around 100 MB/s are slow for large backup sets
Hardware encryption is the reason to pick this over a similar 4TB desktop drive. The 256-bit AES encryption runs in the enclosure rather than in macOS, so the disk contents stay encrypted even if the drive is removed from the Mac and connected to another machine.
For a backup disk that may sit in a closet, travel in a case, or get borrowed, that separation is a real advantage. The bundled device-management and backup software adds password protection on top, though you will need to download and install it, and registration may be required.
Reviewers treat it as a dependable desktop vault and appreciate the encryption and software more than the throughput. The rating split is 73 percent five-star and 8 percent one-star, and the negative slice maps almost perfectly to the two caveats below.
It is a 3.5-inch desktop drive in a plastic enclosure, measuring 9 by 8 by 4 inches, so it needs a power adapter and a permanent home. Read speed sits around 100 to 130 MB/s, and it is backward compatible with USB 2.0 for older machines.
What to check before you commit
Read the software requirements before you buy. The bundled tooling is a download and install, and user account registration may be required, which is friction that does not belong in the middle of setting up a backup.
Make sure your desk has both a power outlet and a Mac within cable reach. With a power brick, this is a two-cord desk arrangement, and the second cord is the reason many people end up moving to a bus-powered desktop drive instead.
Who should skip it
Skip it if you want hardware encryption that is independent of a password you have to remember. The AES function is built in, but the management software adds its own password layer on top, so you still track credentials.
Skip it if you want the fastest possible backups. It is the slowest desktop option here, and on a large first backup the difference is measured in hours.
7. WD My Passport 1TB SSD – Best for Travel for Small-Mac Backup
- Credit-card sized with no flex
- Very fast read and write compared to a mechanical USB disk
- Plug-and-play with no formatting needed
- 256-bit AES hardware encryption and 6.5-foot drop resistance
- Available in five colors which makes backup rotation easy to track
- Included USB-C cable is only about 3.5 inches so it cannot sit beside an iMac
- WD encryption and management app stalls partway through its download
- WD support redirects SSD customers to SanDisk support
If you back up a smaller Mac or a travel machine, 1TB of NVMe storage is enough and this is the small, fast way to do it. The enclosure measures 3.54 by 1.77 by 0.39 inches and weighs 7.08 g, so it is genuinely pocketable rather than merely portable.
Speed is listed at up to 1050 MB/s read with media speed around 1000 MB/s on USB 3.2 Gen 2×2. For Time Machine that means a first backup on a 512GB Mac finishes in a very short sitting, and hourly increments are effectively instant.
The practical detail reviewers mention is the five color options, which sounds trivial until you run a rotation schedule. Different colored drives for different weeks make it obvious which backup is current and which is sitting offsite, without writing anything down.
It is shock and vibration resistant and drop resistant to 6.5 feet, and the 256-bit AES hardware encryption is handled in the drive. Registering the warranty on the WD site is straightforward and gives you a five-year limited warranty.
What to check before you commit
Buy a longer cable. At about 3.5 inches, the bundled USB-C cable means the drive cannot sit on the desk next to an iMac, and reviewers also report the WD encryption and management app stalling partway through its download and erroring on reinstall.
Note the support routing. WD sends SSD customers to SanDisk support because it does not manufacture the drives itself, so know which company answers when you need help on a five-year warranty.
Who should skip it
Skip it if your Mac has 1TB or more of internal storage. A 1TB destination for a 1TB Mac gives you almost no history before Time Machine starts pruning, and that defeats the purpose of having a browsable timeline.
Skip it if you want room to grow. Unlike a 4TB mechanical option, there is no way to expand this capacity without replacing the drive.
8. WD Elements SE 2TB Portable SSD – Smallest Drive for a Permanent Desk Setup
Western Digital 2TB Elements SE – Portable SSD, USB 3.0, Compatible with PC, Mac – WDBAYN0020BBK-WESN
- Smallest and lightest drive tested here at 27 g
- Read speeds up to 400 MB/s beat any legacy USB hard disk
- Runs silently with no power cord so it can stay connected
- Reportedly reliable across two-plus years of daily use
- Good entry point into external SSD storage
- Slower than the 1050 MB/s premium portable SSDs
- Runs noticeably warm during transfers and even at idle on a Mac
- SSD pricing is higher than a mechanical drive of the same capacity
The Elements SE is the drive you leave plugged in. At 27 g and 2.54 by 2.54 by 0.34 inches, it is bus-powered and silent, so a MacBook can sit on a desk with a backup running permanently attached rather than being plugged in each night.
Read speeds are listed at up to 400 MB/s. That is slower than the 1050 MB/s drives here, but it is still several times faster than a mechanical USB disk, and for Time Machine the practical difference between 400 MB/s and 1050 MB/s matters much less than you would expect.
Buyers describe it as the value entry point into external SSDs, and several mention replacing older external hard drives with it. Multiple reviews report problem-free daily use over more than two years, which is the kind of track record you want on a device whose only job is redundancy.
Drop resistance goes to 2 meters and the warranty is a three-year limited manufacturer warranty. It is listed for both PC and Mac, with plug-and-play functionality out of the box.
What to check before you commit
Watch the heat. Warmth during transfers is the most repeated drawback, and one reviewer notes it feels warm even at idle when connected to a Mac. Keep it clear of a laptop’s vent area if that becomes an issue.
Also weigh the 2TB ceiling. On a 2TB Mac this gives you roughly parity with your internal storage, which is thin for hourly history, so it works best as a second target or a machine with lighter usage.
Who should skip it
Skip it if you routinely move very large single files, such as 4K or 8K source libraries. At 400 MB/s the sustained throughput is closer to a mid-tier mechanical array than to a modern NVMe drive.
Skip it if you want a longer warranty. Three years is the shortest cover on this list, and a backup drive is exactly the device where a longer warranty reduces stress.
9. LaCie Rugged USB-C 2TB HDD – Best for Rotating Travel Backups
- Highest average rating in the set at 4.7 stars across 2122 reviews
- Rugged orange rubber shell rated for drops shocks dust and rain
- USB-C interface that is also backward compatible with USB 3.0
- Works with both Mac and PC without additional hardware
- Two-year limited warranty
- 2TB is the smallest capacity here so snapshots age out sooner
- Mechanical HDD with moving parts is slower and less shock-tolerant than an SSD
This is the one to buy if your backup strategy is rotation rather than a permanent desk target. It carries the highest average rating in the group at 4.7 stars, and at 2TB it is small enough that a rotation schedule is genuinely practical instead of aspirational.
The USB-C interface is also backward compatible with USB 3.0 ports, so one cable works between modern and older machines. Reviewers cite that flexibility, along with the rugged orange rubber shell rated for drops, shocks, dust, and rain, as the reasons to pick it.
It is hardware listed for Mac, PC, and Windows, so the drive follows you between a travel laptop and a desktop without a second purchase. The bundle includes one month of Adobe Creative Cloud, which is incidental but not nothing.
Internally it is a 5400 rpm mechanical drive rated at 130 MB/s read. Quiet and predictable, with a two-year limited warranty, and small enough at 7.04 ounces to live in a laptop bag permanently.
What to check before you commit
Two terabytes is the constraint, and reviewers name it directly. It suits rotating backups well because you swap it out, but it ages out sooner than the 4TB options, so expect the oldest snapshots to be pruned more frequently on a busy Mac.
Format it to APFS on first use, as you would with any mechanical target, and give it its own cable in your bag. Spinning platters and travel are a combination that rewards care.
Who should skip it
Skip it if you want one drive to do everything indefinitely. A 2TB mechanical drive that must be carried around is a compromise on both capacity and shock tolerance compared with a single larger desktop option.
Skip it if your Mac is 2TB or larger and you want a long, hands-off history. This is a rotation tool, not an archive.
10. Seagate Expansion Desktop 4TB – Straightforward Desktop Backup Storage
Seagate Expansion Desktop, 4TB, External Hard Drive, USB 3.0 (STKP4000400)
- Large 4TB capacity at a low cost per terabyte
- Automatic recognition by both Windows and Mac
- Backed by Rescue data recovery services
- Simple setup with a power supply and USB cable
- Reads a full 4TB without splitting into partitions
- Requires reformatting before it works as a Time Machine target
- Needs an external power supply so it must stay at a desk
- 5400 rpm mechanical speed limits throughput to about 120 MB/s
The Expansion is the no-drama desktop option. Plug in the power supply and the USB cable, and the drive shows up on a Mac and a PC without hunting for drivers or installing anything first.
Four terabytes at a low cost per terabyte is the whole pitch, and buyers treat it as a straightforward high-capacity backup disk. Rescue data recovery services are included, which is reassuring on a mechanical drive holding your only copy of anything.
Throughput is listed at 120 MB/s read with 9.26 ms average latency on a 5400 rpm spindle, inside an aluminum and glass enclosure weighing 950 g. It is a desk drive with a power brick, and it is designed to stay put.
One Mac-specific step is built into the product listing: reformatting is required before it can serve as a Time Machine target. Plan for that, and the setup is otherwise uneventful.
What to check before you commit
Do the erase to APFS first. It is the one Mac-specific requirement and reviewers are clear that Time Machine will not accept the drive as it ships. Our walkthrough below covers the exact clicks.
Keep the power supply in place. This drive needs an external supply, so unlike the bus-powered desktop option above it adds a second cable to your desk.
Who should skip it
Skip it if you want a drive you can move between machines. With the power brick, this is a stationary unit by design, and there is no battery or bus power to make it portable.
Skip it if you want encryption at the enclosure level. Nothing in the listed specifications provides hardware AES for this drive, so your only protection is FileVault on the Mac itself.
SSD vs HDD for Time Machine: Which One Should You Buy?
Here is the short version: buy an SSD if you want backups that finish before you notice them, and buy an HDD if you want the most terabytes per dollar and do not mind a long first run.
Both formats produce identical Time Machine results. The timeline, the hourly incremental writes, and the browse-and-restore experience are the same on either. The difference is purely mechanical, and it comes down to four things.
First backup duration. A mechanical drive writes large files quickly but small files slowly, and a Mac is mostly small files. A mechanical target runs roughly 100 to 130 MB/s sustained, while the SSDs here sit between 400 MB/s and 1050 MB/s. On a first backup that is the difference between an evening and a short sitting.
Incremental backups. After the first run, Time Machine writes only what changed. Both formats handle that fine, but an SSD finishes the hourly job in seconds, which makes it far more likely the drive stays connected. A backup target people unplug is not a backup.
Durability. An SSD has no moving parts. It survives being dropped in a bag, works in a hot car, and does not care about vibration on a desk. Every mechanical option here carries that risk, and the LaCie Rugged models are the ones designed specifically to reduce it.
Capacity and cost. This is where the HDD still wins clearly. Four terabytes in a portable enclosure, and sixteen terabytes on a desk, are simply not available in SSD form at a sensible price. For a Mac with 2TB or 4TB of internal storage, doubling it is cheaper with spinning disks.
Our rule of thumb: a portable SSD for a laptop you carry, a desktop HDD for a Mac sitting at a desk with large storage. A 2TB Mac that never moves is a poor candidate for a 1TB SSD, no matter how good that SSD is.
One more consideration for SSD buyers that gets little attention. NAND cell type matters more for backup drives than for scratch disks. TLC cells tolerate repeated write cycles far better than QLC, and Time Machine writes to a destination constantly for years. The product listings here do not specify cell type, so if you can confirm it before buying, prefer TLC.
Unrelated to the drive itself but worth checking if you are comparing platforms, our external drive backup storage guide covers how the same capacity maths works for console libraries.
How Big Should a Time Machine Drive Be? The 2x Rule Explained
Double your Mac’s internal storage. That is the rule that shows up on r/mac, r/macbook, and r/MacOS more than any other, and it is right often enough to be a good default.
Why twice? Because your internal drive changes. Applications update, caches grow, and a 1TB Mac that shipped with 400GB free can be nearly full two years later. If your backup destination is only as large as the drive it protects, Time Machine has almost no room to keep anything but the most recent state, and your timeline becomes useless.
The most common complaint on Mac forums is not a failed backup. It is a backup that keeps freezing halfway through because Time Machine is deleting old history to make room for new data. That is an undersized drive, not a broken drive, and no amount of reformatting fixes it.
Worked example: a 2TB Mac that currently uses about 800GB. Double the internal capacity and you get a 4TB destination. Time Machine needs roughly the same amount of space as the data being backed up, plus room to keep several versions of it, so 4TB gives you a workable set of hourly, daily, and weekly snapshots.
Go beyond double when any of these apply. If you edit video or photographs, a single project folder can outgrow a year’s worth of versions. If you keep a large music or photo library that Time Machine duplicates, the backup grows faster than most people expect. If you want a year of daily history rather than a few weeks, add capacity again.
Go below double with care. A 1TB destination for a 512GB Mac is fine. A 1TB destination for a 1TB Mac is not, and that mismatch is the single most common sizing mistake we see.
There is a second, subtler sizing factor: what Time Machine is being asked to back up. By default it excludes external volumes, so a large drive on your desktop is not being copied into your backup. That default is usually what you want, and we cover it in the next section.
Which File System Does Time Machine Need? APFS vs HFS+ vs exFAT
Time Machine wants APFS on any modern Mac. APFS and HFS+ both work, and exFAT usually does not, which is why drives that arrive in exFAT or NTFS seem to be ignored by macOS until you erase them.
APFS (Apple File System) is the native format on every Mac shipped in the last several years. It is required for the fullest Time Machine behaviour, it handles the modern snapshot features cleanly, and it is what Disk Utility offers as the default option when you set up a new volume.
HFS+ (Mac OS Extended Journaled) is the older format. Time Machine will still accept it, and it remains the right choice if you need the drive to be readable by a very old Mac. For anything you are setting up now, APFS is the better answer.
exFAT is the cross-platform format. Windows and Mac both read it without fuss, which is why several drives here ship with it, including the Micron X9. But Time Machine generally will not select an exFAT volume as a destination, so it needs an erase before it will work at all.
The practical sequence is simple. Confirm the drive is erased to APFS, then open Time Machine and select it. If the drive does not appear in the Time Machine options, this is almost always why.
One more wrinkle worth knowing. Several owners of the mechanical LaCie drives on this list report random dismounts or refusal to mount until the drive is reformatted to a Mac-native format. That symptom has the same root cause, so if a LaCie drive misbehaves on your Mac, format it before you return it.
If you need to move data between a Mac and a Windows PC as well as run Time Machine, a partitioned drive solves it cleanly. Format the drive with one APFS partition for backups and one exFAT partition for cross-platform files.
How to Format and Set Up a New Drive for Time Machine in 2026
This is the part that catches people out, and it is the same every time. A new drive arrives with a format that Time Machine will not accept, so you erase it first.
Step 1. Connect the drive to your Mac with a cable you trust. A high-speed USB-C cable matters here more than it seems, and several owners of the SSDs on this list traced intermittent mounting problems to a marginal cable.
Step 2. Open Disk Utility from Applications, Utilities, or Spotlight search. Select your new drive in the left sidebar, choosing the physical drive entry rather than any volume under it.
Step 3. Click Erase. In the Format dropdown choose APFS, pick a name such as Time Machine, and choose GUID Partition Map as the scheme if you are starting from a drive with an existing partition layout.
Step 4. Confirm the erase and wait. Everything on the drive is destroyed, so make sure you are not erasing the wrong entry. The drive disappears and reappears under the name you chose.
Step 5. Open System Settings, then General, then Time Machine. Click Add Backup Disk and select the volume you just created.
Step 6. Turn on Encrypt Backups if you want your backup set locked. Note that encrypting a backup means the data is only recoverable with that password, so store it somewhere you can reach without the drive.
Step 7. Let the first backup run to completion before you judge the drive. It is the longest run Time Machine will ever make, and every later backup is incremental.
That is the whole process, and it works identically on an M-series Mac, on a Mac Studio, and on a Mac mini. None of the drives on this list need Mac-formatted versions from the manufacturer, because the erase takes under a minute.
If you plan to set the same drive up on a second Mac later, remember that an encrypted Time Machine volume stays encrypted. Decide on the password before the first backup, not after you need it.
Beyond the Drive: Partitions, Encryption and Offsite Rotation
A few decisions sit outside the hardware itself, and each of them changes how much stress your setup absorbs.
Does Time Machine back up external drives? By default, no. Time Machine excludes external volumes from the backup set, which is deliberate, because copying one external drive into another backup inflates the set and slows every incremental run. If you have a large working drive on your desktop, back it up separately rather than expecting Time Machine to handle it.
Can one drive do two jobs? Yes. Partition a single drive into an APFS volume for Time Machine and an exFAT or APFS volume for file storage, then point Time Machine at the first partition. The alternative is a dedicated drive, which costs more but removes the temptation to fill your backup volume with media files.
Hardware encryption or FileVault? They solve different problems. FileVault encrypts your Mac’s internal drive and protects data when the machine is off. Hardware AES on the enclosure encrypts the backup disk itself, so it stays protected even when the drive is plugged into another computer. For a backup disk that travels, both together is reasonable.
Should the backup drive live at home? Fire, flood, and theft all take the drive and the Mac together. A second smaller drive, rotated offsite on a simple schedule, is the cheapest real protection. Two drives from different manufacturers is the version forum users recommend, since a shared failure mode defeats a matched pair.
You can also layer cloud backup on top. Time Machine handles full system restores locally, while iCloud or a service like Backblaze covers the case where both the Mac and the drive are gone. Different tools, different failure modes, and the local drive is the one that can bring back a system exactly as it was.
On reliability, the widely cited reference point is Backblaze’s published drive failure statistics, which Mac users on Bogleheads and TidBITS forums repeatedly use to sanity check a buying decision. No external drive is failure-proof, and the practical response is the rotation schedule rather than a specific brand.
Finally, remember that Time Machine keeps local snapshots on your Mac’s internal drive for automatic hourly backups even when the external drive is disconnected. Those snapshots are not a substitute for an external backup, but they do cover the case where you forgot to plug the drive in last night.
Frequently Asked Questions
Can an Apple Time Machine backup an external drive?
Time Machine does not back up external volumes by default. It backs up your Mac’s internal drive to a separate external drive you designate, and it excludes other external drives from the backup set to keep it small and fast. If you have a large working drive, back it up with a second destination rather than expecting Time Machine to include it.
Should I use an SSD or HDD for Time Machine backups?
Both produce identical Time Machine results, and the timeline works the same on either. An SSD finishes a first backup far faster and handles hourly increments in seconds, and it has no moving parts, so it survives being carried around. An HDD offers far more capacity for the money, which is why doubling a large Mac’s internal storage is still cheaper with spinning disks.
Does Apple still support Time Machine backups?
Yes. Time Machine remains a built-in feature of macOS, and it is still the fastest native way to restore a Mac to a working state after a failure, an upgrade, or an accidental deletion. The removal of wireless Time Capsule support pushes users toward external drives, but the core Time Machine workflow is unchanged.
How big of a drive do you need for a Time Machine backup?
Double your Mac’s internal storage as a default. Time Machine needs roughly as much room as the data being backed up, plus space for several versions of it. If your destination is close to the size of your internal drive, old snapshots get deleted to make room, and the backup can stall partway through while it prunes history.
What format does a Time Machine drive need?
APFS is the format to choose for any Mac you are setting up today. HFS+ also works, and exFAT generally does not, which is why a new drive that ships formatted as exFAT or NTFS will be ignored by Time Machine until you erase it. Open Disk Utility, select the drive, click Erase, and choose APFS before adding it in Time Machine settings.
Can I use my Time Machine drive for regular file storage too?
You can, but partitioning is the better method. Split one drive into an APFS volume for Time Machine and a second APFS or exFAT volume for files, then point Time Machine at the first partition. A dedicated drive is cleaner, since it removes the temptation to fill your backup volume with media and fill your backup history early.
Our Final Verdict on the Best External Drives for Time Machine Backups
The best external drives for Time Machine backups in 2026 come down to two questions. How fast do you want the first backup, and how much history do you want to keep?
For speed and durability, the SanDisk Extreme 2TB is our pick, with measured throughput close to 1050 MB/s, IP65 sealing, and a five-year warranty. For capacity on a budget, the WD Elements 4TB gives you twice the storage of a typical Mac for the least money here. For hands-off long-term archiving, the Seagate One Touch 16TB ends drive rotation entirely.
Whatever you choose, size it at roughly twice your Mac’s internal storage, erase it to APFS before the first run, and consider a second smaller drive rotated offsite. A backup you never have to think about is the entire point.