What is MicroSD UHS-II?
MicroSD UHS-II (Ultra High Speed Phase II) is a high-performance microSD memory card standard that uses an additional row of electrical contacts to deliver significantly faster data transfer speeds than UHS-I cards. It is designed for demanding applications such as 4K/8K video recording, high-speed photography, drones, action cameras, and professional data transfers while remaining backward compatible with many UHS-I devices.
Key Takeaways
UHS-II is a faster microSD interface standard than UHS-I.
Features a second row of pins for higher bandwidth.
Supports theoretical transfer speeds of up to 312 MB/s.
Ideal for professional cameras, drones, and high-resolution video.
Works in UHS-I devices but operates at UHS-I speeds if the host lacks UHS-II support.
History & Evolution
The SD Association introduced UHS-II to overcome the bandwidth limitations of UHS-I as cameras and storage-intensive devices began producing larger files. As 4K video, burst photography, and high-resolution media became common, faster memory card interfaces became essential.
The evolution generally follows:
Standard Speed SD
High Speed SD
UHS-I
UHS-II
UHS-III
SD Express
MicroSD versions of these standards bring the same technology to compact devices.
Why Does MicroSD UHS-II Exist?
Modern devices generate much larger files than earlier generations.
UHS-II was created to:
Reduce file transfer times
Support high-bitrate video recording
Improve continuous burst photography
Prevent storage bottlenecks
Enable faster professional workflows
How Does MicroSD UHS-II Work?
Unlike UHS-I cards, a UHS-II microSD card includes two rows of electrical contacts.
The first row maintains backward compatibility.
The second row provides an additional high-speed communication channel.
Compatible devices use both rows to achieve much higher transfer speeds.
Older devices ignore the second row and communicate using the original interface.
This design allows the same card to function across both older and newer hardware.
Key Characteristics
Ultra High Speed Phase II interface
Dual-row pin design
Higher bandwidth than UHS-I
Low latency for demanding workloads
Backward compatible with UHS-I devices
Available in multiple storage capacities
Important Specifications
| Specification | MicroSD UHS-II |
|---|---|
| Interface | UHS-II |
| Maximum Bus Speed | Up to 312 MB/s |
| Pin Configuration | Dual-row contacts |
| Backward Compatibility | Yes |
| Typical Applications | 4K/8K video, drones, cameras |
| Form Factor | microSD |
Actual read and write speeds depend on the card, card reader, and host device.
Compatibility: What Devices Work with MicroSD UHS-II?
MicroSD UHS-II cards are compatible with:
Professional cameras
Mirrorless cameras
DSLR cameras (with adapters where supported)
Drones
Action cameras
Mobile devices that support microSD
Professional card readers
Laptops with compatible readers
When used in a UHS-I device, the card functions normally but is limited to UHS-I performance.
Advantages
Extremely fast file transfers
Better support for high-resolution video
Faster image buffer clearing
Improved workflow for creators
Backward compatibility with older devices
Reliable performance for professional workloads
Limitations
Higher cost than UHS-I cards
Maximum speed requires UHS-II-compatible hardware
Many smartphones do not benefit from UHS-II speeds
Performance varies by manufacturer and card quality
Common Uses
MicroSD UHS-II cards are commonly used for:
4K and 8K video recording
RAW photography
Continuous burst shooting
Drone aerial footage
Action cameras
Professional media production
High-speed file backups
MicroSD UHS-II vs UHS-I
| Feature | MicroSD UHS-II | MicroSD UHS-I |
|---|---|---|
| Maximum Bus Speed | Up to 312 MB/s | Up to 104 MB/s |
| Contact Pins | Dual-row | Single-row |
| File Transfer Speed | Much faster | Moderate |
| Professional Video | Excellent | Good |
| Backward Compatibility | Yes | Yes |
| Typical Price | Higher | Lower |
Buying Considerations
When choosing a MicroSD UHS-II card, consider:
Whether your device supports UHS-II
Required storage capacity
Sustained write speed for video recording
Video Speed Class (V30, V60, V90)
Application requirements
Brand reliability and warranty
Common Misconceptions
"A UHS-II card is always three times faster."
No. Maximum speed is only achieved when both the card and the device support UHS-II.
"UHS-II is only for professional photographers."
Not entirely. Drone operators, videographers, and anyone transferring large files frequently can also benefit.
"UHS-II cards do not work in UHS-I devices."
Incorrect. They are backward compatible but operate at UHS-I speeds.
Real-World Examples
Recording 8K footage on a professional mirrorless camera
Capturing long RAW photo bursts during sports events
Flying drones that record high-bitrate 4K video
Transferring hundreds of gigabytes of footage using a UHS-II card reader
Related Technology Terms
UHS-I – The first Ultra High Speed SD interface supporting up to 104 MB/s.
UHS-III – A newer SD interface with even higher bandwidth than UHS-II.
SD Express – SD card technology that uses PCIe and NVMe for SSD-like performance.
Video Speed Class – Ratings such as V30, V60, and V90 indicating sustained video recording performance.
microSDXC – A microSD capacity standard supporting cards from 64 GB up to 2 TB.