SD	miniSD	microSD
Full Size (Up to 2GB)
High Capacity (4GB to 32GB)
Extended Capacity (Over 32GB up to 2TB)

SD memory cards come in a variety of speed classes and three different physical sizes: SD, miniSD, and microSD. The SD card is typically used in personal computers, video cameras, digital cameras and other large consumer electronics devices. The microSD and miniSD cards are commonly used in smaller electronic devices like mobile phones. Some manufacturers offer adapters to fit a traditional SD card slot, allowing even greater versatility and flexibility to use the card in a mobile phone as well as a computer or video camera.

To determine the right card for your device, always consult the device’s user manual or contact the manufacturer. All SD memory card formats are readily available in the marketplace and can be found in a range of retail outlets including drug stores, electronics and computer shops and Internet sites.

Choosing the Best Card – What Memory Capacity do I Need?

SD memory cards come in a variety of memory capacities designed to fit your needs and budget. The next-generation SD memory card specification, SDXC, offers the greatest memory capacity and UHS SDHC and SDXC products offer the fastest performance. Your device’s users manual may help you select the memory that is right for your device. You can also determine the best memory capacity based on how you plan to use the card. For cameras, consider the picture resolution of every photo, and for your MP3 player, the bit-rate required for smooth playback. Take a look at our reference chart that illustrates the various storage capacities.

How to Pick the Best Speed

For greatest performance, users should pair their devices with the corresponding SD memory card. Your device user’s manual will help you select the SD memory card performance that will maximize your device performance.

SD Speed Class/UHS Speed Class

Greater Performance Choices

There are two kinds of Speed Class, “Speed Class” and “UHS 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. Speed Class and UHS Speed Class provide the constant speed necessary for video recording by designating a minimum writing performance so that minimum and constant speed is guaranteed for camcorders, video recorders and other devices with video recording capabilities under the conditional write operation specified in the specification.

Speed Class, designated as Class 2, 4, 6 and 10, is designed for normal and high speed bus interface (mode) and UHS Speed Class 1 is designed for UHS-I bus interface*. (Speed Class and the UHS Speed Class are not compatible.)

*UHS (Ultra High Speed), the fastest performance category available today, defines bus-interface speeds up to 104 Megabytes per second for greater device performance in SDXC and SDHC host products.

	Marks	Operable Under…	Applications	SD Memory Card
Speed Class		Normal Bus I/F	SD video recording	SD, miniSD, microSD SDHC, miniSDHC, microSDHC SDXC, microSDXC
			HD ~ Full HD video recording
		High Speed Bus I/F	Full HD video recording HD still consecutive recording
UHS Speed Class		UHS-I Bus I/F	Full higher potential of recording real-time broadcasts and capturing large-size HD videos	SDHC UHS-I and SDXC UHS-I

UHS Speed Class Compatibility

Speed Class Compatibility

Fragmentation and Speed

The memory of a card is divided into minimum memory units. The host writes data onto memory units where no data is already stored. As available memory becomes divided into smaller units through normal use, this leads to an increase in non-linear, or fragmented storage. The amount of fragmentation can reduce write speeds, so higher SD card speeds help compensate for fragmentation.

The SD Association has specified operating conditions for SDHC, SDXC, SDHC UHS-I and SDXC UHS-I memory cards to guarantee the minimum speed according to the card’s speed class. Speed logos are provided to help identify cards that comply with these specifications.