What do SD, SDHC, and SDXC Flash Memory Card Standards Signify?
![](https://www.cactus-tech.com/wp-content/uploads/2019/03/SD-SDHC-and-SDXC-Logos.fw-5296992e.png)
SD refers to the original Standard Capacity SD Card. SDHC refers to SD High Capacity and SDXC represents SD eXtended-Capacity.
There is also a non-memory standard called SDIO for SD IO Devices with wide ranging functions such as Wi-Fi, GPS, Cameras, FM Radio, Bluetooth, Digital TV Tuner, Scanner, Voice Recorder and others.
SD Standards, Specs and Logos
SD Standard Capacity
2GB and lower Capacities
- FAT12 and FAT16 File System
- SD, miniSD and microSD form factors supported
- Cactus Industrial Grade SD and microSD Cards support this standard
SD High Capacity
From 4GB to 32GB in Capacity
- FAT32 File System
- SD, miniSD and microSD form factors supported
- Sometimes represented as SDHC, microSDHC
- Cactus Industrial Grade SD and microSD Cards and Industrial MLC SD Cards support this standard
SD eXtended-Capacity
From 64GB to 2TB in Capacity
- exFAT File System
- SD, miniSD and microSD form factors supported
- Sometimes represented as SDXC, microSDXC
- Cactus Industrial MLC SD Cards support this standard