SD card case

Understanding SD Cards

  by Dustin MainNo Comments

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They are the music cassette, the VHS tapes, and the film of our generation.

If you have a camera, music player, video camera, or a mobile phone, chances are one of the bunch uses an SD memory card (or one of its smaller family members) to store your stuff.  In a perfect world, you would just grab one off the shelf and pop it into your gadget of choice and all would be well.

Unfortunately in the tech world, names, sizes and speed specs all crash together in a blaze fueled with confusion over model numbers and changing standards.

sandisk2gb-sd-tma    sandisk16gb-sdhc-6-tma     sandisk32gb-sdxc-u1-tma

Confused yet?  Let’s make it simple.

Here’s what you need to know about SD cards.

The SD Card Family

The SD card family is a relatively small one.  With 3 main types of cards, the biggest question is which one fits in your gear.

Here’s what they look like.

sd-card-tma minisd-card-tma microsd-card-tma




Most popular, used in most digital cameras

Smaller size than SD, support being phased out

The smallest SD format currently available.  Popular in mobile phones & tablets

up to 2TB

up to 32GB

up to 2TB

What You Need to Know

Be sure to check your gadget out before you buy a card as you can’t fit a square peg into a round hole.  Likely your device will be made with one type of card in mind, though you can sometimes fit a smaller card into a larger device with an adapter in a pinch.

SD Card Storage Size

Over the years, SD cards have gone through 3 standards and from storing 1MB to a road map with 2TB cards on the way (2 million times larger).  The larger you choose, the more files, photos, movies and music you can store.

Here are the logos.











High Capacity

Extended Capacity

What You Need to Know

Check to see which format your device is compatible with, and you will be able to use those cards as having backwards compatibility with the smaller storage types.  For example, if your device is compatible with SDHC, you may also use SD.

There is one more thing to note.  Just because your device is compatible with a storage format, doesn’t mean it can work with all sizes.  Your mobile phone may work with SDXC, but only up to 64GB.  Check with the manufacturer for details.

SD Card Speed

The SD card speed is how fast the card can read or write data.  Sounds boring?  Well if you shoot high definition video, or like to shoot using your camera’s burst mode you’ll definitely want to pay attention.

Here is what to look for.



Speed Classes

UHS Speed Class

2 / 4 / 6 / 10 MB/s Speed (minimum)

<50 MB/s

What You Need to Know

Newer devices will show a speed class mark on them.  Use this class (or faster) for best performance.  Using a slower class card may slow impede performance by increasing your time between shots with your camera, or making you unable to shoot high-definition video.  It may also increase the time it takes to move files onto your computer.

You may have some older cards lying around without a speed class mentioned, or a speed like “x133.”  This is the old standard, and based on CDROM speeds, which is fortunately being dropped.

Bits & Pieces

So now that you can you can make sense of all the information on an SD Card, what do you buy?  Here are some tips:

Stick with a Brand You Know

At TMA, we like Sandisk (check prices) and Lexar (check prices), two memory companies that have been in the game a long time.  The bigger brands have a little more at stake when it comes to quality and reputation, and that is good since the last thing you want to happen is to lose all of your photos due to a defective card.

Buy as Big as Your Budget Allows

If you’re looking to buy a card or two, spend a bit more to get the bigger, faster cards if you have the cash for it.  I’ve never heard someone say “oh I wish my memory card held less stuff.”

That said, there is a good reason to have a spare card or two in your bag, so keep that in mind.

Buy from a Reputable Seller

While not such a problem in North America or Europe, there are certainly some fake memory cards around.  Buy from a company like or your local electronics shop.  Steer clear of the hole-in-the-wall shops (especially as you travel) and deals that are too good to be true.

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About the Author

Dustin Main

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Dustin just can't get enough travel or technology, but when he's not directly feeding one of those insatiable habits, you can probably find him at some far away ice cream shop taking pictures of empty cups. That, or on top of a mountain somewhere shooting photos and finding adventures to share on his website "A Skinny Escape".

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