Differences between MicroSD and SD Card
Contents
Physical design and dimensions[edit]
The Secure Digital (SD) format is a non-volatile memory card standard managed by the SD Association (SDA). Introduced in 1999 by a partnership between SanDisk, Panasonic, and Toshiba, the standard was intended to improve upon the MultiMediaCard (MMC). The microSD format was later introduced in 2005, originally known as TransFlash, to provide a smaller footprint for mobile telephones.[1]
A standard SD card measures 32 mm by 24 mm with a thickness of 2.1 mm. By contrast, a microSD card measures 15 mm by 11 mm and is 1.0 mm thick. Due to this size difference, microSD cards are typically used in compact devices such as smartphones, action cameras, and drones. Standard SD cards are commonly found in larger electronics, including digital single-lens reflex (DSLR) cameras, video recorders, and laptop computers.
Another physical distinction is the presence of a mechanical write-protect switch on full-sized SD cards. When engaged, this slider prevents the host device from writing new data or deleting existing files. MicroSD cards lack this physical switch due to their small surface area.
Comparison of card types[edit]
| Feature | Standard SD | MicroSD |
|---|---|---|
| Dimensions | 32 mm x 24 mm x 2.1 mm | 15 mm x 11 mm x 1.0 mm |
| Weight | Approx. 2.0 grams | Approx. 0.25 grams |
| Write-protect switch | Physical slider on card side | None (software-controlled only) |
| Number of pins | 9 pins (UHS-I) | 8 pins (UHS-I) |
| Native slot usage | Cameras, PCs, Consoles | Smartphones, Drones, Tablets |
| Adapter compatibility | Generally none | Fits SD slots via passive adapter |
Technical specifications and speed classes[edit]
Both formats share identical storage capacity standards defined by the SDA. These include SDHC (High Capacity) for cards between 4 GB and 32 GB, SDXC (Extended Capacity) for cards between 32 GB and 2 TB, and the SDUC (Ultra Capacity) specification, which supports up to 128 TB. Both cards also utilize the same bus interfaces, such as UHS-I, UHS-II, and UHS-III.[2]
The transfer speeds are categorized by Speed Class (2, 4, 6, 10), UHS Speed Class (U1, U3), and Video Speed Class (V6, V10, V30, V60, V90). While the internal technology is the same, standard SD cards sometimes offer higher sustained performance in high-end categories like V90 because their larger casing allows for better heat dissipation during long video recording sessions.
Interoperability[edit]
MicroSD cards are electrically compatible with standard SD host devices. A passive adapter allows a microSD card to fit into a full-sized SD slot. These adapters contain no electronic components and simply map the microSD pins to the standard SD pin layout. Standard SD cards cannot be used in microSD slots because there is no physical way to reduce the card size.
