Almost any external drive works with a Mac; the 'for Mac' label on a listing means it arrived pre-formatted, which takes a minute to change yourself. What actually matters is the format you choose, whether the drive is a Time Machine target or a working volume, and whether your Mac's port supports the interface specification you are paying for.
12 in-stock listings · no moving parts, interface as the maker states it
Best cost per terabyte here right now: Crucial X Series 8TB Portable SSD at $100.46/TB ($804 for 8TB, portable ssd, used listing). The drive inside it is not disclosed by the maker.
| Model | Capacity | Interface | Inside | Warranty | Condition | $/TB | Price | |
|---|---|---|---|---|---|---|---|---|
| Crucial X Series 8TB Portable SSD | 8TB | USB 3.2 | NOT DISCLOSED | — | USED | $100.46 | $804 | Buy |
| Crucial X Series 6TB Portable SSD | 6TB | USB 3.2 | NOT DISCLOSED | — | USED | $101.96 | $612 | Buy |
| SanDisk Extreme 8TB Portable SSD | 8TB | USB 3.2 GEN 2 | NOT DISCLOSED | — | NEW | $105.00 | $840 | Buy |
| Crucial X Series 8TB Portable SSD | 8TB | USB 3.2 | NOT DISCLOSED | — | NEW | $105.75 | $846 | Buy |
| Crucial X Series 6TB Portable SSD | 6TB | USB 3.2 | NOT DISCLOSED | — | NEW | $107.33 | $644 | Buy |
| SanDisk Extreme 2TB Portable SSD | 2TB | USB | NOT DISCLOSED | — | USED | $110.00 | $220 | Buy |
| Samsung T Series 4TB Portable SSD | 4TB | USB 3.2 GEN 2 | NOT DISCLOSED | — | USED | $132.25 | $529 | Buy |
| WD Elements 2TB Portable SSD | 2TB | USB 3.0 | NOT DISCLOSED | — | NEW | $134.35 | $269 | Buy |
| SanDisk Extreme 2TB Portable SSD | 2TB | USB | NOT DISCLOSED | — | NEW | $139.48 | $279 | Buy |
| SanDisk Extreme 2TB Portable SSD | 2TB | USB 3.2 GEN 2 | NOT DISCLOSED | — | USED | $141.07 | $282 | Buy |
| Crucial X Series 1TB Portable SSD | 1TB | USB 3.2 | NOT DISCLOSED | — | NEW | $143.03 | $143 | Buy |
| SanDisk Extreme 2TB Portable SSD | 2TB | USB 3.2 GEN 2 | NOT DISCLOSED | — | NEW | $149.00 | $298 | Buy |
“Inside” is not disclosed by any maker for these products and the contents vary by batch, so we state that rather than guessing — see what the community has found by opening them. Warranty shows a dash because the makers' warranty pages did not resolve through our source-verification path; read the term on the maker's page for the exact model. Interface is the maker's own specification string, not a speed measurement.
12 in-stock listings · 2.5in, runs on USB power alone
Best cost per terabyte here right now: Seagate Expansion 24TB Portable HDD at $30.10/TB ($722 for 24TB, portable hdd, new listing). The drive inside it is not disclosed by the maker.
| Model | Capacity | Interface | Inside | Warranty | Condition | $/TB | Price | |
|---|---|---|---|---|---|---|---|---|
| Seagate Expansion 24TB Portable HDD | 24TB | USB 3.0 | NOT DISCLOSED | — | NEW | $30.10 | $722 | Buy |
| WD My Passport 4TB Portable HDD | 4TB | USB 3.1 | NOT DISCLOSED | — | USED | $31.88 | $128 | Buy |
| Seagate Expansion 20TB Portable HDD | 20TB | USB 3.0 | NOT DISCLOSED | — | USED | $32.50 | $650 | Buy |
| Seagate Expansion 20TB Portable HDD | 20TB | USB 3.0 | NOT DISCLOSED | — | NEW | $37.50 | $750 | Buy |
| Seagate Expansion 6TB Portable HDD | 6TB | USB 3.0 | NOT DISCLOSED | — | NEW | $39.17 | $235 | Buy |
| Seagate One Touch 4TB Portable HDD | 4TB | USB 3.0 | NOT DISCLOSED | — | USED | $39.75 | $159 | Buy |
| WD Elements 5TB Portable HDD | 5TB | USB 3.2 GEN 1 | NOT DISCLOSED | — | USED | $40.39 | $202 | Buy |
| WD My Passport 4TB Portable HDD | 4TB | USB 3.1 | NOT DISCLOSED | — | USED | $41.25 | $165 | Buy |
| WD Elements 6TB Portable HDD | 6TB | USB 3.2 GEN 1 | NOT DISCLOSED | — | USED | $41.50 | $249 | Buy |
| Seagate Expansion 12TB Portable HDD | 12TB | USB 3.0 | NOT DISCLOSED | — | NEW | $41.58 | $499 | Buy |
| Seagate Expansion 24TB Portable HDD | 24TB | USB 3.0 | NOT DISCLOSED | — | NEW | $41.67 | $1000 | Buy |
| WD My Passport 5TB Portable HDD | 5TB | USB 3.1 | NOT DISCLOSED | — | USED | $42.63 | $213 | Buy |
“Inside” is not disclosed by any maker for these products and the contents vary by batch, so we state that rather than guessing — see what the community has found by opening them. Warranty shows a dash because the makers' warranty pages did not resolve through our source-verification path; read the term on the maker's page for the exact model. Interface is the maker's own specification string, not a speed measurement.
12 in-stock listings · 3.5in, needs a mains adapter, cheapest per TB
Best cost per terabyte here right now: WD My Book 16TB Desktop HDD at $18.69/TB ($299 for 16TB, desktop hdd, used listing). The drive inside it is not disclosed by the maker.
| Model | Capacity | Interface | Inside | Warranty | Condition | $/TB | Price | |
|---|---|---|---|---|---|---|---|---|
| WD My Book 16TB Desktop HDD | 16TB | USB 3.0 | NOT DISCLOSED | — | USED | $18.69 | $299 | Buy |
| WD My Book 22TB Desktop HDD | 22TB | USB 3.0 | NOT DISCLOSED | — | NEW | $28.75 | $632 | Buy |
| Seagate Expansion 16TB Desktop HDD | 16TB | USB 3.0 | NOT DISCLOSED | — | NEW | $30.28 | $484 | Buy |
| Seagate Expansion 8TB Desktop HDD | 8TB | USB 3.0 | NOT DISCLOSED | — | USED | $31.72 | $254 | Buy |
| WD Elements 20TB Desktop HDD | 20TB | USB 3.0 | NOT DISCLOSED | — | USED | $33.64 | $673 | Buy |
| Seagate Expansion 8TB Desktop HDD | 8TB | USB 3.0 | NOT DISCLOSED | — | NEW | $34.00 | $272 | Buy |
| Seagate Expansion 10TB Desktop HDD | 10TB | USB 3.0 | NOT DISCLOSED | — | NEW | $34.21 | $342 | Buy |
| WD Elements 16TB Desktop HDD | 16TB | USB 3.0 | NOT DISCLOSED | — | USED | $34.96 | $559 | Buy |
| WD Elements 20TB Desktop HDD | 20TB | USB 3.0 | NOT DISCLOSED | — | NEW | $35.02 | $700 | Buy |
| Seagate One Touch 8TB Desktop HDD | 8TB | USB-C | NOT DISCLOSED | — | NEW | $36.25 | $290 | Buy |
| WD Elements 10TB Desktop HDD | 10TB | USB 3.0 | NOT DISCLOSED | — | NEW | $36.46 | $365 | Buy |
| WD My Book 8TB Desktop HDD | 8TB | USB 3.0 | NOT DISCLOSED | — | USED | $37.50 | $300 | Buy |
“Inside” is not disclosed by any maker for these products and the contents vary by batch, so we state that rather than guessing — see what the community has found by opening them. Warranty shows a dash because the makers' warranty pages did not resolve through our source-verification path; read the term on the maker's page for the exact model. Interface is the maker's own specification string, not a speed measurement.
Western Digital and Seagate both sell Mac-labelled versions of their portable lines, and the difference between those and the standard versions is smaller than the shelf placement implies. A Mac-labelled drive arrives formatted for macOS and usually ships with a USB-C cable rather than a USB-A one. The hardware is otherwise the same drive in the same enclosure.
Any external drive reformats for macOS in about a minute using Disk Utility, and the process is not technical: select the drive, choose Erase, pick a format and a scheme, confirm. If a standard version of the same model is cheaper per terabyte than the Mac version, buy it and spend the minute.
The one place the label genuinely helps is at the checkout of somebody who does not want to think about it, which is a legitimate thing to pay a small premium for. It stops being legitimate when the premium is large, and the tables above make that visible: if the Mac variant is meaningfully dearer per terabyte, you are paying a lot for a formatting step.
The cable question is more real than the formatting one. A modern Mac has USB-C ports, and a drive shipping with a USB-A cable needs an adapter or a different cable. That is a few dollars rather than a reason to pay a premium, but it is worth checking so the drive is usable the day it arrives.
This is the decision that actually matters, and it is decided by one question: will any machine other than a Mac ever need to read this drive?
APFS is Apple's own file system and it is what macOS is built around. It is the required format for a Time Machine target on modern macOS, it handles snapshots and encryption natively, and it is the right choice for anything that lives in the Apple ecosystem. Windows cannot read it without third-party software, which is the entire trade-off.
exFAT is the cross-platform option: macOS, Windows and most other systems read and write it without extra software. That makes it correct for a drive that moves between machines, hands work to a Windows user, or plugs into equipment that is not a computer. What you give up is the resilience features of a modern file system — exFAT has no journaling, which means an unplug during a write is more likely to leave damage than it would be on APFS.
The practical rule is straightforward. A Time Machine drive is APFS, because macOS requires it. A drive that only ever touches Macs is APFS, because there is no reason to accept exFAT's weaknesses. A drive that crosses platforms is exFAT, and on that drive you eject properly every time rather than pulling the cable.
Mac OS Extended, the older HFS+ format, still appears in Disk Utility and in older guidance. There is no reason to choose it for a new drive on modern macOS unless you are specifically supporting an old machine that cannot read APFS.
Time Machine is a versioned backup system, which means it does not store one copy of your data — it stores your data plus as much history as it can fit. That single fact determines how large the drive should be, and it is the thing most people get wrong.
The commonly repeated guidance is a target at least twice the size of the data being backed up, and the reasoning behind it is sound: at 1:1 the drive fills almost immediately and Time Machine spends its life deleting the history that makes it useful. At 2:1 or better you keep months of versions, which is what turns a backup into something that can recover a file you broke three weeks ago rather than only a disk that died this morning.
Measure the data rather than the disk. A 2TB Mac with 400GB actually used needs a target sized against the 400GB, not the 2TB, and that changes the answer substantially. Check the used figure in About This Mac before you buy.
Buying a rung up is usually cheaper per terabyte anyway, which the tables above show directly, and it removes the most common failure mode of a Time Machine setup: a drive that filled, started thinning history aggressively, and quietly became a much worse backup than its owner believed.
One structural point: a Time Machine drive attached permanently to the Mac it backs up is a second copy but not an off-site one, and most of what destroys the original also takes it. Our backup guidance covers the rotation that fixes this cheaply.
Every drive in the tables above carries the maker's own interface designation — USB 3.2 Gen 2, USB 3.2 Gen 2x2, USB4, Thunderbolt — and we do not interpret those into a speed ranking. What is worth stating as a compatibility matter is that the designation is only available if both ends support it.
A Mac's USB-C ports are not all the same specification, and the shape of the connector tells you nothing about what runs through it. Thunderbolt ports carry USB as well, but a USB drive on a Thunderbolt port does not become a Thunderbolt drive. A drive specified at a higher designation connected to a port that does not support it operates at the port's specification, which is a fact about the connection rather than a fault in either device.
The practical consequence is to check your Mac's port specification before paying a premium for a higher one on the drive. Apple's technical specifications page for the exact model states it. Paying for a designation your machine cannot use is the most common avoidable overspend in this category.
The cable matters too, and it is genuinely a common failure: many USB-C cables are charge-only or carry a lower data specification, and a drive connected with the wrong cable behaves as though the drive is at fault. Use the cable that came with the drive, and if you replace it, replace it with one rated for the data specification you need.
The three families in the tables above suit genuinely different Mac situations, and picking by price alone produces the wrong answer in both directions.
A portable SSD is the right buy for a laptop that travels, carries work in progress, and gets connected and disconnected many times a day. The design properties that justify the premium are physical rather than performance: no moving parts to survive being knocked while running, a fraction of the size and weight, and no spin-up delay when you plug it in. For a MacBook that lives in a bag, those are worth real money.
A portable hard drive is the right buy for the same portability requirement without the premium, on a drive that is handled carefully and carries archives rather than active work. You pay considerably less per terabyte and accept a mechanical device in a bag.
A desktop hard drive is the right buy for anything that stays on a desk: Time Machine targets, media libraries, archives. It is the cheapest storage per terabyte in this cluster by a wide margin, and the mains adapter that makes it non-portable is irrelevant to a drive that never moves. For a Mac mini or an iMac in a fixed position, this is almost always the correct family.
The mixed answer is common and sensible: a desktop drive as the Time Machine target and a portable SSD for work that travels. They are different jobs and buying one drive to do both means overpaying for the archive or under-equipping the travel.
No. It arrives pre-formatted for macOS and usually ships a USB-C cable; the hardware is otherwise identical. Any external reformats in Disk Utility in about a minute. If the standard version is cheaper per terabyte, buy it and spend the minute — the tables above show both where they are in stock.
APFS if it only ever touches Macs, and APFS is required for a Time Machine target on modern macOS. exFAT if any Windows machine or non-computer device needs to read it. exFAT's cost is the absence of journaling, so an unplug mid-write is more likely to leave damage — eject properly on exFAT drives every time.
At least twice the data you are actually backing up, measured against used space rather than disk size. Time Machine stores your data plus as much version history as fits, so a 1:1 target spends its life deleting the history that makes it useful. Check the used figure in About This Mac, then buy a rung up — it is usually cheaper per terabyte anyway.
Only if the port supports that specification, and the connector shape tells you nothing about what runs through it. A drive on a higher designation connected to a port that does not support it operates at the port's specification. Check your Mac's technical specifications page before paying the premium — this is the most common avoidable overspend here.
You can partition it, and it is usually a false economy. Time Machine expands to fill whatever it is given, so sharing a drive means either starving the backup of version history or constantly managing partition sizes. Two drives is a cleaner arrangement and, at desktop capacities, an inexpensive one.
It depends on whether the drive travels. A portable SSD earns its premium on a drive that lives in a bag and gets connected all day — no moving parts, pocketable, no spin-up delay. A desktop hard drive is the right and much cheaper answer for a Time Machine target or archive that stays put. Many people sensibly buy one of each.
Specification claims on this page were checked against the pages below on 4 August 2026. Where a widely-repeated figure did not survive that check, we report what the source says now and say so in the text rather than repeating the familiar number.