Understanding Memory Cards: SD/SDHC/SDXC

Are you interested in buying a memory card but you’re not sure which type of memory card is going to be the best choice or whether or not the card is even going to be compatible with your device? Here is a brief explanation of the SD card family what kind of specifications you might run into when purchasing a memory card and whether or not it will be compatible with your particular device.

Choosing a Memory Card – Daunting Titles and Descriptions

When choosing a memory card it can be a little daunting or even confusing trying to understand the different types of SD cards currently available.

What is the difference between a SanDisk Ultra 32GB microSDHC UHS-I Card with Adapter and a SanDisk Ultra 64GB microSDXC UHS-I Card with Adapter anyways?

Besides the 64GB memory card having twice as much storage capacity as a 32GB memory card both cards are of the same physical size (both are micro cards, and we’ll discuss physical sizes of memory cards later), both have the same minimal transfer speed (both are UHS-I or class 10 memory cards, which we are going to briefly talk about in this guide but you can review understanding memory cards and their speed class rating systems for more information about how to choose the fastest memory card for your device), and apart from both coming with adapters (also discussed below) one of the more confusing parts of these titles is that one is a SDHC card while the other is a SDXC card.

The SDHC and SDXC indicate that these are two separate types of SD cards in the SD card family.

Memory Card Family

There are currently three main types of memory cards in the SD family; SD, SD High Capacity (SDHC) and SD Extended Capacity (SDXC).

Here is a brief explanation about these three different types of memory cards, their specifications and compatibility.


The SD Card (Secure Digital Card) is an ultra small flash memory card. It has been in use since 1999, is the first generation of such memory cards and its type of format has become the industry standard.

The original first generation SD card should work in any device that utilizes SD, SDHC, or SDXC type memory cards but the capacity on these types of SD cards are usually limited and range from 128MB to 2GB.


The SDHC (SD High Capacity) memory card was released in 2006 and follows the 2.0 SDA (SD Association) specifications. This second generation memory card uses a different format than the original and as such SDHC memory cards are not backwards compatible and will not work on devices that only take the first generation SD card. Please note however that devices which were manufactured in or after 2009 should be SDHC compatible.

SDHC Cards have a maximum storage capacity of 32GB.


SDXC (SD Extended Capacity) Cards use the SDA 3.0 specifications and their storage capacity can range from 64GB to 2TB. SDXC Cards are not backwards compatible with devices which only accept SD or SDHC type memory cards.

Devices manufactured in or after 2011 should be able to accept and be able to use SDXC type memory cards.

Check the Specs

The specifications of the device you are interested in getting a card for should let you know what type of memory card it is able to accept.

The newer the device the more types of technology that device can often utilize. So while you might not be able to use an SDXC type memory card in an older device which only accepts SDHC type cards if you have a newer device which accepts SDXC type cards then that device should be backwards compatible and should allow you to use SDXC, SDHC and SD type memory cards.

Just don’t forget to check the other specifications required from the device such as the Speed Class and Size/Capacity of the card as well. You wouldn’t be able to use a Class 8 type card in a device which requires a Class 10 or higher.

What about UHS memory cards?

UHS stands for Ultra High Speed and refers to the Speed Class of the memory card. UHS can apply to both SDHC and SDXC type memory cards.

Different Physical Sizes

For smart devices such as cameras, tablets and smartphones, SD cards consist of three physical sizes and the types of memory cards mentioned above (SDXC, SDHC and SD) will often be available in one of the following physical sizes…

  • Standard SD Card – a regular or standard sized SD, SDHC, or SDXC memory card is 24mm wide, 32mm long and is 2.1mm thick.
  • MiniSD Card – miniSD and miniSDHC memory cards are 20mm wide, 21.5mm long and 1.4mm thick (the SDXC family is not available in the mini size).
  • MicroSD Card – microSD memory cards are designed for smaller devices such as smartphones and are one of the smaller sizes available. MicroSD cards have a width of 11mm, a length of 15mm, and a thickness of 1mm. You can have a microSD card, a microSDHC card, or a microSDXC card; all of which look pretty similar to one another physically but should be labeled with their corresponding type.
  • Adaptors – Don’t forget that you can buy an adapter for your microSD card which will allow you to use that microSD card in either a miniSD adapter or a regular SD adapter for devices which may require a larger card.

Thanks for Reading

I hope that this guide has helped shed some light on some of the different types of cards you might encounter on your search for the perfect memory card.

If you are in the market for a new memory card for your smartphone then don’t hesitate to review how to choose the best memory card for an Android or Windows phone you might find the advice and information in that guide helpful in your search as well.

Thanks for visiting this site and I hope you have a great day.

This INTEL was submitted by:

If you found this content

Informative Helpful Instructive Beneficial Valuable Educational Useful



Help others find this by sharing it...

5 thoughts on “Understanding Memory Cards: SD/SDHC/SDXC”

  1. Thank you for sharing this…
    It’s a very helpful article for us to know more about the “Memory Card Family”. I am really impressed.

  2. LV Home Restoration

    Good info
    Most people do not know anything about these little storage units. It is always good to have a guide out there so people can store all of those photos that they snap.

Leave a Reply

Your email address will not be published. Required fields are marked *