SDHC (Secure Digital High Capacity) is an extension of the SD (Secure Digital) card standard which increases the flash memory card's storage capacity up to 32 GB. The SD format itself is based on the older MMC format. (see SD Card vs MMC)

Comparison chart

SD Card versus SDHC comparison chart
Edit this comparison chartSD CardSDHC
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  • current rating is 3.46/5
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Capacity Up to 2GB From 4-32GB
Compatibility Compatible only with SD host devices Not backward compatible; Devices that do not specifically support SDHC do not recognize SDHC memory cards. However, host devices that support SDHC will also support older SD cards.
Stands for Secure Digital card Secure Digital High Capacity
Types Standard SD, mini SD and micro SD SDHC, mini SDHC, micro SDHC
Speed Slower as compared to SDHC Default speed: 12.5MB/s; High speed: 25MB/s; With UHS-I: Up to 104 MB/s. With UHS-II: 156 MB/s (half duplex) or 312 MB/s (full duplex)
Filesystem FAT16 FAT32
What is it? It is a flash memory card format. It is a flash memory card format.
Developed It was developed by Matsushita, SanDisk and Toshiba in 1999. SD Card Association
Size 24 mm × 32 mm × 2.1 mm 24 mm × 32 mm × 2.1 mm.


SD cards used byte addressing, which limited the amount of memory it could support to 4GB. The newer SDHC standard uses sector or word addressing, which increases addressable storage to theoretically support capacities up to 2 TB (2048 GB). The current SDHC standard limits the maximum capacity of an SDHC card to 32 GB but it is expected that the specification will be revised to allow card capacities greater than 32 GB. In early 2010, SanDisk started offering a 64GB SDHC card.


SDHC cards have the same size and electrical form factor as older SD cards, so SDHC-devices also support SD cards. However, the reverse is not true. An SD card reading device will not support the newer SDHC standard. Look for SD/SDHC logo on the package/manual for host compatible devices such as digital cameras, digital video camcorders, and mobile phones.

File System

SDHC cards are typically formatted as FAT32, while SD cards are typically formatted with the FAT16 file system. However, both types of cards can support other general-purpose file systems, such as ext2 and UFS2. The Micro/mini SD card is compatible with 1.0/1.1 software and the Mini/Micro High capacity (SDHD) runs on a 2.0 software - the 2.0 still works with the normal micro SD but the Micro SD high capacity does not work with the 1.0/1.1.


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"SD Card vs SDHC." Diffen LLC, n.d. Web. 13 Feb 2019. < >