Understanding speed classes
The SD card association defines card speeds using two terms: Speed Class and UHS Speed Class.
- Speed class is the original rating used and the number defines the card speed; 4 for 4MB/s, 6 for 6MB/s. etc.
- UHS (Ultra High Speed) uses minimum write speeds to differentiate the cards; UHS-I Speed Class 1 has a minimum write speed of 10MB/s while UHS-I Speed Class 3 has a minimum write speed of 30MB/s.
What the logos mean
It’s easy to select a card that matches the interface and speed class required by the host device, such as a camera or camcorder.
Works with conventional devices
UHS-I Speed Class
Works with a UHS-I compliant device
Supports the UHS-I interface