Today Western Digital is taking the wraps off of the industry’s first microSDXC card with a 400 GB capacity. The card is aimed at Google Android-based smartphones or tablets and can run applications that require A1 performance class spec. Meanwhile, given the current shortage state of the NAND market combined with its class-leading density, the price of the card is not going to be low, with pricing running closer to that of a higher-end SSD.

The Western Digital is not disclosing which NAND flash chips are used by the SanDisk Ultra microSDXC 400 GB card, but given the capacity of the device, it is highly likely that we are dealing with modern, high capacity 3D NAND. When it comes to performance, the microSDXC card uses the UHS-I bus and features transfer speeds of up to 100 MB/s. In addition, the card is compliant with the SD Association A1 Application Performance specification and therefore supports sustained sequential performance of 10 MB/s and at least 1500 random read and 500 random write IOPS. In addition, the card is designed to sustain extreme conditions and can operate in the range between -13ºF to 185ºF (-25ºC to 85ºC).

To simplify usage of the card, Western Digital offers an updated version of the SanDisk Memory Zone app that helps to organize data on Android-based devices and easily back it up to the card.

SanDisk Ultra microSDXC 400 GB Card at Glance
Usable Capacity ~400 GB
Read Speed up to 100 MB/s
Write Speed
Minimum Sequential Write Speed 10 MB/s
Operating Temperatures -13ºF to 185ºF (-25ºC to 85ºC)
Interface UHS-I
Availability Fall 2017
SDA Labels A1, UHS-I, Class 10, U1

The 400 GB SanDisk Ultra microSDXC UHS-I card will be available shortly from and other retailers in the U.S. for $249.99, which is a rather high price for a memory card. A good news is that the product is covered by a 10-year warranty.

Related Reading:

Source: SanDisk

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  • Kjella - Thursday, August 31, 2017 - link

    Try a 10TB drive, 25 times this capacity and you won't get 250MB/s sustained...
  • ZeDestructor - Friday, September 1, 2017 - link

    With a good UHS-I/II reader (Like the Kingston MobileLite G4 (FCR-MLG4)), this should do 50MB/s sustained, meaning a little over 2 hours to fill it up, not 11 hours.
  • R7 - Saturday, September 2, 2017 - link

    10MB/s? Where did you get this number? It's more than likey 100MB/s and if it were UHS-II standard it would do nearly 300MB/s. I guess they went for capacity instead of speed on this one.
  • Tams80 - Sunday, September 3, 2017 - link

    It's really intended to be filled up all at once though. I mean, you could do that if you wanted to, but that's likely not been a focus when they were designing it.

    The speeds are only really designed for use as storage for cheap to prosumer cameras, and for fairly mild write and read demands from devices. Hell, it'll be good enough for the Nintendo Switch.
  • Mikewind Dale - Thursday, August 31, 2017 - link

    $249 for 400 GB is not bad at all. Especially when it's ***Micro*** SD that can fit in your phone.
  • jwcalla - Thursday, August 31, 2017 - link

    I'd like to have this in my phone and then I can do weekly tarball backups of my desktop computers to my phone.
  • ferhad22 - Monday, October 23, 2017 - link

    This plus a Nifty Minidrive (a microSD reader that sits flush with the slot) will make a nice.
    <a href="">باربری </a>
    That's just nuts! Talk about having confidence in your product.
  • ferhad22 - Monday, October 23, 2017 - link

    <a href="">باربری </a>

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