Application Performance Class Knowledge Base

The Introduction of Adoptable Storage

Adoptable Storage is a new feature supported by Android™ Marshmallow 6.0 and later versions that formats an external microSD card to act like internal storage. Adoptable Storage allows users to have a better integrated experience between the card and the phone and gives users more space on their phone for applications. Before Adoptable Storage, most applications could be launched solely from the smartphone’s internal storage, but now users can run applications directly from the installed microSD card.

Setting Up Adoptable Storage

  1. Insert your SanDisk microSD card.
  2. The Android phone will ask you to choose either “Use as portable storage” or “Use as internal storage”.
  3. Choose “use as internal storage” to allow the card to store pictures, videos, music, files, and applications. The card will be formatted, encrypted, and treated as additional internal storage capacity for your individual Android device, so you won’t be able to use it in other devices.

Before Adoptable Storage

After Adoptable Storage

The Evolution of microSD Cards & the Introduction of Application Performance Class

In the past, microSD cards have primarily been used with digital cameras and other mobile devices to expand capacity for photos, videos, music, and many other digital files. These files are recorded through sequential writing. The new Adoptable Storage feature requires microSD cards to have a role beyond reading and writing large photo, video, and music files. Smartphones have additional functionalities like email, games, and texting, which means that this data must be recorded and retrieved in an entirely different way, called random access.

Ultimately, smartphones with Adoptable Storage need a card that can keep up with their many different functionalities. Therefore, the new Application Performance Class was created to indicate that the card can support smartphones’ random and sequential performance needs.

What is A1?

Application Performance Class

Minimum Random Read

Minimum Random Write

Minimum Sustained Sequential Write

1500 IOPS1 500 IOPS1 10MB/s

To meet Application Performance Class 1 (A1), the card is required to have a random read performance of at least 1,500 IOPS, a random write performance of at least 500 IOPS, and a minimum sustained sequential performance of 10MB/s under specified conditions.

Compared to a non-A1 card, an A1 card will launch applications faster. This new Application Performance Class was specifically designed with smartphone users in mind and works to optimize your mobile experience. 

microSD Cards that Support A1


  • Capture Full HD video
  • For 64GB-400GB: Up to 100MB/s read speed for transferring files. For 16GB-32GB: Up to 98MB/s read speed for transferring files.1
  • Expand smartphone capacity up to 400GB*


  • Capture 4K UHD video
  • Up to 100MB/s read speed for transferring files.1
  • For 128GB-256GB: Up to 90MB/s write speed for super-fast capture. For 32GB-64GB: Up to 60 MB/s write speed for super-fast capture.1
  • Expand smartphone capacity up to 256GB*


How much faster will my phone go? Will it make my camera faster and video better?
microSD cards with A1 specification will not improve the results of taking photos and video, but may speed up consumers’ viewing experience.

How much faster can I load apps with an A1 card versus a non-A1 card?
This depends on many factors including the size and complexity of the app. 


*IOPS= Input/Output operations per second; measured by the number of 4KB read/write commands that can be executed per second. Source: SD Card Association (

* 1GB=1,000,000,000 bytes. Actual user storage less.

1 1MB=1,000,000 bytes.