SD Speed Class/UHS Speed Class/Video Speed Class

/SD Express Speed Class

Greater Performance Choices

There are four kinds of Speed Classes, “Speed Class”, “UHS Speed Class”,  “Video Speed Class” and “SD Express Speed Class.”

As a characteristic of flash memory, actual transfer speed varies. Variable speeds are difficult to reliably record streaming content such as video because it requires a constant writing speed. All speed class types assures minimum sequential card access performance including multiple stream access (in SD Express Speed Classes) under defined conditions specified by the standard. It is most important for video recording and other applicationsIt is also applicable for any write or read applications that requires an assured minimum constant sequential access performance. 

SD Standard SDHC Standard SDXC Standard SDUC Standard
Capacity up to 2GB more than 2GB up to 32GB more than 32GB up to 2TB more than 2TB up to 128TB
File System FAT 12, 16 FAT 32 exFAT exFAT
Form Factor Size SD 32 x 24 x 2.1 mm
microSD 11 x 15 x 1.0 mm

Speed Classes
NS mode C2, C4, C6
HS mode C2, C4, C6, C10,V6, V10
UHS-I mode C2, C4, C6, C10U1, U3V6, V10, V30
UHS-II & III mode C4, C6, C10U1, U3V6, V10, V30, V60, V90
SD Express mode E150, E300, E450, E600

SD Speed Class

Video Format

*Intra video, is a compression technique performed relative to information contained only within the current frame, and not relative to any other frame in the video sequence. Therefore, it is usually larger in size.