The following are Speed Class ratings for SD, SDHC and SDXC memory cards:
- Class 2: Recommended for Standard Definition video recording
- Class 4: Recommended for High Definition video recording
- Class 6: Recommended for High Definition video recording
- UHS Class 1 (U1): For recording large-sized High Definition video
- UHS Class 3 (U3): Capable of recording 4K video
NOTE: The Speed Class rating represents the minimum writing performance for recording video and is the official unit of speed measurement as defined by the SD Association. For complete information, visit the SD Association website.