SDmicroSDkaarte

SDmicroSDkaarte, or SD and microSD memory cards, are small removable flash storage devices used to store digital data in a wide range of consumer electronics. They were introduced for portable data retention and have become standard media for cameras, smartphones, drones, and many embedded systems.

Form factors and capacities

The microSD family is the smallest of the SD card formats, measuring about 15 by 11 by 1 millimeters. It includes microSD, microSDHC (High Capacity), microSDXC (Extended Capacity), and the newer microSDUC (Ultra Capacity). Capacities scale with the standard: microSD up to 2 terabytes with SDXC, and microSDUC specifications indicating much higher potential limits, though actual availability varies. Real-world cards commonly range from a few gigabytes to 1 terabyte. Many microSD cards are sold with adapters to fit standard SD slots.

Performance classes

Cards carry speed ratings that indicate minimum write speeds and sustained performance. Traditional Class 2, 4, 6, and 10 designations were replaced in practice by UHS (U1, U3) and Video Speed Class (V10, V30, V60, V90). Higher classes support smoother recording and faster data transfer, which is important for high-resolution photography and 4K/8K video.

File systems and compatibility

For cards larger than 32 GB, exFAT is commonly used, while smaller cards may use FAT32. Compatibility depends on the device’s SD interface and firmware; not all devices support the latest capacities or exFAT. MicroSD adapters enable use in devices that require a standard SD form factor.

Usage and care

SD/microSD cards are ubiquitous in mobile devices, cameras, drones, and single-board computers. They should be ejected properly, kept away from extreme heat and moisture, and formatted in the device for best reliability.

See also: SD Association, microSDXC, SDHC, SDXC, SDUC.