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Seagate Expansion Portable, 1TB, External Hard Drive, 2.5 Inch, USB 3.0, for Mac and PC (STKM1000400)
Seagate

Seagate Expansion Portable, 1TB, External Hard Drive, 2.5 Inch, USB 3.0, for Mac and PC (STKM1000400)

Bottom line: The Seagate Expansion Portable: 1TB in a 2.5-inch pocketable body, no power brick needed; main trade-off: reformatting required before Time Machine backups will work.

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By , Founder & Editor-in-Chief · Listing data updated

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.

Pros & Cons

Pros

  • ✓ 1TB in a 2.5-inch pocketable body, no power brick needed
  • ✓ Bus-powered over a single USB 3.0 cable
  • ✓ Auto-recognized by Windows and Mac out of the box
  • ✓ Includes Rescue Data Recovery Services plus limited warranty

Cons

  • ✗ Reformatting required before Time Machine backups will work
  • ✗ Usable capacity comes in under the labeled 1TB
  • ✗ USB 3.0, not USB-C or Thunderbolt speeds
  • ✗ Spinning 2.5-inch mechanical drive, so slower than an SSD

Manufacturer description

The Seagate Expansion Portable gives you 1TB of plug-and-play storage in a 2.5-inch shell that slips into a jacket pocket or laptop sleeve. It draws power over the single USB 3.0 cable, so there is no wall adapter to pack and no separate power brick to lose on a trip. Setup is genuinely hands-off: the drive is automatically recognized by both Windows and Mac systems, and saving files is a drag-and-drop away rather than a software install and account signup. That makes it a straightforward way to consolidate photos, movies, and music into one place and free up space on a crowded internal SSD…

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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.

Frequently Asked Questions

Does the Seagate Expansion Portable work with a Mac?

Yes. The drive is automatically recognized by both Windows and Mac computers for simple setup. If you want to use it with Time Machine, Seagate notes that reformatting is required first.

Do I need a separate power adapter?

No. The Expansion Portable is USB 3.0 powered, so the single data cable also supplies power. There is no wall adapter to carry.

Do I have to install software to use it?

No setup software is required for basic use. Seagate designed it around drag-and-drop file saving, so you copy files to the drive the same way you move them between folders.

Will I actually get the full 1TB of space?

Not quite. Seagate states that available storage capacity may vary, so formatted usable space will be somewhat less than the 1TB on the label.

What happens if the drive fails?

It ships with a limited warranty and Rescue Data Recovery Services included. Check the product listing for current warranty length and Rescue coverage terms in your region.

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

BrandSeagate
ColorBlack
Item Width8.1 centimeters
Model NameSeagate Expansion
Read Speed120 megabytes_per_second
Unit Count1 Count
Form Factor2.5-inch, Portable
Item Length12.2 centimeters
Media Speed1.2E+2 megabytes_per_second
ConnectivityUSB
Model NumberSTKM1000400
CompatibilityPC, Mac
Built-In MediaSeagate ExpansionPortable Drive 1TB USB3.0
Hard-Drive Size1 TB
Mfr Part NumberSTKM1000400
Number of Items1
Special FeaturePortable
Hardware PlatformMac, PC
Installation TypeExternal Hard Drive
Compatible DevicesDesktop

Ready to buy?

Seagate Expansion Portable, 1TB, External Hard Drive, 2.5 Inch, USB 3.0, for Mac and PC (STKM1000400) is listed on Amazon. Price, availability, shipping and returns are set by Amazon and its sellers — check the listing for current terms. SpecPicks earns a small commission on qualifying purchases — thank you for supporting independent review work.

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Seagate Expansion Portable, 1TB, External Hard Drive, 2.5 Inch, USB 3.0, for Mac and PC (STKM1000400)
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