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.

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Source: SanDisk

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  • B166ER - Thursday, August 31, 2017 - link

    Wait.... when did SanDisk become part of WD???
  • HomeworldFound - Thursday, August 31, 2017 - link

    The middle of last year, May I think.
  • Bullwinkle J Moose - Thursday, August 31, 2017 - link


    This is a very good sign

    Hopefully we will soon begin seeing their SSD's match that warranty
  • phoenix_rizzen - Thursday, August 31, 2017 - link

    That's just nuts! Talk about having confidence in your product.

    I haven't been able to keep a MicroSD card usable beyond 3-5 years; and had 32 GB one fail in my Pi3 just last week. Granted, the larger ones (64 and 128 GB) do seem to be holding up better than the smaller ones (1, 8, and 32 GB) I've used. More cells to do wear-levelling over, and probably more over-provisioning as well (at least in the really large ones, 200+ GB).
  • imaheadcase - Friday, September 1, 2017 - link

    It is meaningless though. Warranty for the most part are just marketing. Its like giving a 10 year warranty on a USB cable. They know you are not doing it, because by the time it actually does need warranty help its standard is useless they don't even make them.

    I read someplace walmarrt extended warranty on items people buy nets them 50million+ a year, only like %1 of people ever need to use it.
  • timecop1818 - Sunday, September 3, 2017 - link

    No, you're not going to forget about warranty on a 400GB SD card unless you're fucking stoned.
  • Bullwinkle J Moose - Thursday, August 31, 2017 - link

    Probably not though....

    SD card always have a longer warranty as they are not used nearly as much as an SSD
  • Rictorhell - Thursday, August 31, 2017 - link

    Anandtech you have made my year! I have been looking for this product or something like it, for months now! :p Completely makes up for a crappy day here.
  • fletom - Thursday, August 31, 2017 - link

    This plus a Nifty Minidrive (a microSD reader that sits flush with the slot) will make a nice Time Machine drive. Of course, it would only protect against drive corruption and accidental deletion, not loss or theft, so you'd need a second backup drive to go along with it.
  • CommandoCATS - Thursday, August 31, 2017 - link

    At 10MB/s (ideal) this is gonna take 11+ hours to fill up completely...practically speaking more like 15+. My question is has there ever been a storage media that takes longer to completely fill up. Some backup tapes come to mind, maybe some parallel port hard drives from back in the day.

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