If you own a digital camera, there will probably come a time when you’ll need to purchase an additional SD card for it (even though most cameras come with one).

SD cards, also called media cards, memory cards, and flash cards, are the storage devices your digital camera use to hold your digital picture files.

Although some cameras have built-in flash storage, most use SD cards which can be inserted and removed, allowing you to switch them out from your camera.

This flexibility allows you to do such things as…

  • Remove the SD card from the camera and insert it into a computer media card reader for copying your pictures to your computer.
  • Remove a filled SD card from the camera and insert an empty one, keeping the filled card as a backup or even the primary storage of the picture files on it.
  • Remove a filled SD card from the camera and insert an empty card so you can continue taking pictures in the field.

If you ever do need to purchase an SD card for your digital camera or some other digital device, keep in mind that there are 3 differences in the cards that you’ll need to know.


(1) Physical card size

SD Card Size

There are currently three physical sizes of SD cards.

  • Standard Size – most common size used in digital cameras
  • MiniSD – no longer commonly used, they originally were found in early mobile phones.
  • MicroSD – commonly used in mobile phones and smart phones, but also used in some digital cameras and tablets.



micro adapterAlthough you’ll need to purchase the card size that fits your particular camera, there are adapters that allow MicroSD cards to be used in cameras that require a Standard size.


(2) Card Capacity

Just like any other computer storage device, SD cards have different storage capacities. Over the years, different “capacity standards” have been developed. Here are the three most common:

  • sd card capacity standardsSD standard – sizes up to 2GB
  • SDHC standard – sizes from 2GB to 32GB
  • SDXC standard – sizes from 32GB to 2TB


The different SD cards will have the logos you see here on the right, to indicate which capacity standard they belong to.

Most newer cameras can use any of the three capacity standards, but if you have an older digital camera, be sure to check your manual to see which capacity standards are supported.


(3) Speed Class

SD cards also vary in their speed.  The speed class of the card refers to how quickly data (the picture file) can transfer between the camera and the card flash storage.

Although most digital cameras do not require that you have an SD card of a certain speed, the speed is still important because it determines how quickly a picture is saved before you can take another shot. Speed especially becomes important with cameras that have larger megapixel sizes since there is more data to save as a picture is taken.

Having a faster SD card is also important if you want to record video with your camera, especially high definition (HD) video.  In fact, some digital cameras that also record video require a certain SD card speed, otherwise they won’t record.

The bottom-line is, when you purchase an SD card, getting one with a faster standard will let you take pictures more quickly.

Over the years, 3 speed classes have been developed for SD cards. Each class has its own special marking and numbering system.

Here is a summary table that shows the speed classes, their symbols, and the speeds.  Again, although digital cameras can use any of the speeds for regular digital photography, remember that a faster speed means you can take pictures more quickly.

But also remember that speed DOES matter with video.  And in the table I’ve also included which card speed class is needed for the different types of video recording.


To summarize, each SD card will have one of the above symbols indicating its speed.  Using the above table, you can see which card will give you higher speeds, and therefore faster saving of your pictures.

Choosing the right SD card – Summing it all up

Here is an example of an SD card that shows the various symbols that were mentioned earlier in this article.

SD card example symbols

Using all the you’ve learned in this article, when I personally shop for a new card, here are the questions/facts I consider…

  • What size card does my camera take?
    My main camera requires the standard size
  • What capacity do I Want?
    I typically look at the SD card prices, and choose a capacity that is at a good price point (i.e. the capacity that if you jump up to the next size, would cost too much).
  • What is the speed?
    Since I want to quickly take pictures, and I also take a lot of video, I always look for a card that has at least a UHS Class 1 (Speed Class 10) or better.

As always, I would love to hear your comments or questions.  Please leave them below!!!