Seagate

Seagate Expansion Portable, 4TB, External Hard Drive, 2.5 Inch, USB 3.0, for Mac and PC (STKM4000400)

Name: Seagate Expansion Portable, 4TB, External Hard Drive, 2.5 Inch, USB 3.0, for Mac and PC (STKM4000400)
Brand: Seagate
SKU: B08ZJFH7Y1

Status: Seagate Expansion Portable (4TB hard drive): Unavailable on Amazon as of 2026-10-21 04:13 UTC. Closest in-stock match (same 4TB hard drive): Seagate Portable 4TB External Hard Drive HDD, $189.99 on Amazon as of 2026-10-21 12:20 UTC (price may vary). eBay sellers may still list this model new or used.

View Current Price — $189.99 🛒 Search eBay for this model

Bottom line: The Seagate Expansion Portable: 4TB in a 2.5-inch bus-powered shell - no wall adapter needed; main trade-off: must be reformatted before it works with Apple Time Machine.

Unavailable on Amazon as of 2026-10-21 04:13 UTC

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Currently unavailable on Amazon. Not the same product — an in-stock alternative with matching specs:

Same 4TB hard drive: Seagate Portable 4TB External Hard Drive HDD — $189.99 on Amazon as of 2026-10-21 12:20 UTC (price may vary).

View Current Price — $189.99

Original listing (currently unavailable) → Compare to similar external storage

By Mike Perry, Founder & Editor-in-Chief · Listing data updated 2026-10-21

Mike Perry — Hardware researcher since 2014. For external drives and portable storage, synthesises manufacturer specs and independent reviews rather than first-hand lab testing. Core beat: GPU performance across gaming, rendering, and local-LLM inference. About the author →

Pros & Cons

Pros

✓ 4TB in a 2.5-inch bus-powered shell - no wall adapter needed
✓ USB 3.0 drag-and-drop backup, no software to install
✓ Auto-recognized by Windows and Mac out of the box
✓ Includes limited warranty plus Rescue Data Recovery Services

Cons

✗ Must be reformatted before it works with Apple Time Machine
✗ Spinning 2.5-inch platter drive, far slower than portable SSDs
✗ USB 3.0 only - no USB-C connector on the drive
✗ No hardware encryption or password lock on the enclosure

Manufacturer description

Expansion portable drive is an easy-to-use solution for instantly adding storage to Windows or Mac—and taking those files on the go. Take advantage of fast data transfer speeds with USB 3.0 and consolidate files into a single location. Free up space on your computer with a simple drag and drop—file saving is that easy.

SpecPicks Verdict

SpecPicks scored Seagate Expansion Portable using a rating × review-volume × price-fit model applied to published specs and reviews across the external storage category. Seagate's external storage lineup sits within the broader category mid-tier; price and specs are the deciding factors over brand loyalty here. Judge it on the specification table and the price rather than on sentiment: check the figures that decide your use case, then put it side-by-side with two or three close alternatives in the Compare tool before clicking through.

Common buyer scenarios for external storage of this kind: matching it to an existing build, replacing a failing part, or upgrading from a previous-generation equivalent. Check the spec table below against your current setup — particularly socket / form-factor / power-rating fields — and confirm compatibility on the retailer's listing before purchase. Prices and stock are set by the retailer and may have moved since this page was last updated.

Key Features

Sleek and simple portable drive design for taking photos, movies, music, and more on-the-go
Drag-and-drop file saving
USB 3.0 powered
Automatic recognition of Windows and Mac computers for simple setup (Reformatting required for use with Time Machine)
Enjoy peace of mind with the included limited warranty and Rescue Data Recovery Services
The available storage capacity may vary.

Full Specifications

Brand	Seagate
Color	Black
Item Width	8.1 centimeters
Model Name	Seagate Expansion
Read Speed	120 megabytes_per_second
Unit Count	1 Count
Form Factor	Portable
Item Length	12.2 centimeters
Media Speed	120 megabytes_per_second
Connectivity	USB
Model Number	STKM4000400
Compatibility	PC, Mac
Built-In Media	Seagate ExpansionPortable Drive 4TB USB3.0
Item Type Name	Hard Drive
Hard-Drive Size	4 TB
Mfr Part Number	STKM4000400
Number of Items	1
Special Feature	Portable
Hardware Platform	Mac, PC
Installation Type	External Hard Drive

Ready to buy?

Amazon shows no buyable offer for Seagate Expansion Portable at the last check. The closest in-stock match with the same 4TB hard drive is Seagate Portable 4TB External Hard Drive HDD. SpecPicks earns a small commission on qualifying purchases — thank you for supporting independent review work.

View Current Price — $189.99