What do SD, SDHC, and SDXC Flash Memory Card Standards Signify?

There are four main families of SD Card products with three related to memory devices.

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 Commercial Grade 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 Commercial Grade SD Cards support this standard

Steve Larrivee has over 30 year's experience in the data storage market, including 5 years at Seagate Technology and 10 years at SanDisk. He joined Cactus Technologies Limited as an equity partner and Co-Founded Cactus USA in 2007 with partner Tom Aguillon. Learn more about Steve on Google+