Definition: SD card classes

The categories of SD flash memory cards for recording video. The three class types are Speed, UHS Speed and Video Speed. Devices that support any of the UHS buses also support the earlier Default and High Speed bus. See SD Card and SD Express.

  Bus        Bus Speed
  Interface  (MB/sec)
  Default       12.5
  High Speed    25
  UHS I        104
  UHS II       312
  UHS III      624
  SD Express   985  (Gen 3x1 lane)
  SD Express  1970  (Gen 3x2 lane)
  SD Express  3940  (Gen 4x2 lane)

                     Max. Video
  Speed Class        Resolution
   C6    Default        HD
   C10   High-speed     HD

  UHS Speed Class (2010)
   U1    UHS-I/II/III   HD
   U3    UHS-I/II/III   4K

  Video Speed Class (2016)
   V6    UHS-I/II/III   HD
   V10   UHS-I/II/III   4K
   V30   UHS-I/II/III   4K
   V60   UHS-II/III     8K
   V90   UHS-II/III     8K

Speed Class Markers

C, U and V designate the speed class, while Roman numerals are the bus type. (Images courtesy of SD Association and SanDisk Corporation.)

More Pins

Starting with the UHS-II bus, the cards have a second row of pins. (Image courtesy of SD Association.)

misc

Term of the Moment

discrete transistor

Look Up Another Term

Definition: SD card classes