What is an SDHC Memory Card?

SD and SDHC Memory Cards are some of the most popular types of memory cards in use in digital cameras at the moment. Although both types of memory cards look virtually identical, there are some differences. The most noticeable difference will be the capacity of the cards.

Card Capacity

The original SD card ranged from 1MB to 4GB. SDHC extends the original device and now supports capacities of up to 32GB, although there is a theoretical limit of 2TB. Any card under 4GB is known as a standard SD card, and any card over this is an SDHC card.


Although SDHC devices are backwards compatible with SD and even MMC cards, the opposite is not true. SDHC cards cannot be used in SD devices unless they specifically support the new standard. It's not even possible to use the first 4GB of a high capacity card because they are different.

Some devices may be able to support SDHC with the help of a firmware upgrade from the camera manufacturer. Whether or not the manufacturer issues an upgrade is completely up to them.


SDXC is a new extension of SD cards and this allows for cards of over 32GB right up to the theoretical limit of 2TB or 2048GB. SDXC is still a very new technology and isn't supported by many pieces of hardware; it is supported in Linux and Windows 7.

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