by Tucker Mindrum

SanDisk Ultra microSDXC 128GB Card Review

The SanDisk Ultra microSDXC 128GB memory card is optimized for smartphone, tablet, or camera users looking to maximize their storage space. It is compatible with Android and Windows phones and can be used with any SD card accepting camera (it comes with an SD card adaptor). While it does offer the most storage available in any microSD card on the market today, the user does sacrifice some performance; at a reported read speed of 30MB/s, it is one of the slowest microSD cards that SanDisk makes. However, for many users this trade-off would be an easy one to justify; this card could be fully appreciated by anyone that uses their phone or camera to capture lots of HD video or images without wanting to clear the card as frequently. 

As with other of SanDisk's microSD cards, the Ultra microSDXC is waterproof, shockproof, X-ray proof, and tolerant of extreme temperatures. This provides the user with peace of mind that their stored media will be even safer than the devices that use the card.

The Ultra SDXC carries a price tag of $199.99 and comes with a 10-year warranty.


  • Model: SDSDQUA-128G – 128GB
  • Form Factor: microSDXC
  • Performance/speed: up to 30MB/s read and <30MB/s write
  • Card Dimension: 0.59” x 0.043” x 0.03” (15mm x 11mm x 1.0mm)
  • Card Dimensions with Adaptor: 1.26” x 0.94” x 0.08” (24mm x 32mm x 2.1mm)
  • Operating Temperature: -25 to 85°C
  • Storage Temperature: -40 to 85°C
  • Compatibility: Compatible with microSDHC and microSDXC supporting host devices
  • Warranty: 10 years

Design and Build

The general design of the Ultra microSDXC is similar to other microSD cards, and can be used with both microSDHC and microSDXC devices. SanDisk also includes the full size SD card adaptor to make it easy to fit into most computers and digital cameras. 

The entire front of the card is black with red branding and the back is identical to other microSD cards; it has eight gold pins with the circuit board layout and NAND package with a small sticker indicating the model number. 


Using our Consumer Testing Platform, we measured transfer speeds from the SanDisk Ultra microSDXC 128GB with IOMeter. Its sequential activity was measured at 44.66MB/s and 14.29MB/s for read and write, respectively, and random large-block performance was found to be 43.98MB/s and 2.45MB/s for read and write, respectively. Both read values were higher than those reported by SanDisk; the company doesn't disclose expected write speeds other than to say they'll be slower than the read performance. 

When compared with the SanDisk Extreme PLUS microSDXC 64GB card, we see the scope of the Ultra microSDXC card's performance compromise; the Extreme PLUS microSDXC dominated in all areas, scoring sequential transfer speeds of 89.41MB/s and 58.51MB/s for read and write, respectively, and random transfer speeds of 82.10MB/s and 41.54MB/s for read and write, respectively.

While it's unfair to compare the Extreme Plus to the Ultra, doing so does give a complete picture as to what the user should expect. In this case you get double the capacity in a single card, but half the read performance and fractional write performance. In the grand scheme of things, for most who are considering the card to meet capacity needs, the speeds will be fine and many of the use cases will be read-oriented anyway - music playback video viewing, and so on. 


The SanDisk Ultra microSDXC 128GB is perfect for users that desire huge storage capabilities and don't mind lower performance compared to other of SanDisk's microSD cards. The card to which we compared the Ultra microSDXC, the Extreme PLUS microSDXC, provides some perspective for the Ultra microSDXC. With the 128GB Ultra, the user effectively gives up about half of the performance speed for twice the capacity. Potential buyers should be not judge the Ultra microSDXC too harshly on performance though, the card will still accomplish all it is asked in the target use cases.

The biggest knock may be the current street price of roughly $200, which translates to a 4X price premium and only a 2X capacity boost when compared to SanDisk's 64GB Ultra microSD card. It is early though and pricing will fall more in line as production ramps. For those who have a serious need for the extra capacity, price is unlikely to be a deterrent anyway, there just simply isn't another single card solution for capacity strapped end users.


  • Industry leading capacity point
  • Ten year warranty
  • Excellent build


  • Slower transfer speeds than most microSD memory cards

The Bottom Line

The SanDisk Ultra microSDXC 128GB memory card is a great option for consumers looking to maximize the storage capabilities of their Android or Windows phone or camera without having to compromise by juggling multiple cards or storage platforms.

SanDisk Ultra microSDXC 128GB at Amazon

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