Choosing a memory card

Choosing a memory card for your 4K camera. You received a new camera for the holidays. But new cameras often lead to a need for new or just more memory cards. The problem is cards are often labeled in confusing ways. Cards like most other types of tech are labeled with what looks like intentionally confusing techno babel. You will see speed ratings. Different standards.  Even different card types.

What to look for

So what should you look for? The first thing to look at is the type of card.  Smaller cameras (For example action cams) often use micro SD cards.  Larger cameras use full size cards. There are adapters that allow you to use micro cards in normal card slots. But you can’t use full size cards into micro slots. They won’t fit.

How to check

Your first stop should be your user manual. Most cameras ship with a printed manual. Some companies have stopped shipping paper manuals. They require you to download the manual from their websites. If you don’t have a manual micro cards are the type used in cell phones. Full size cards are substantially larger.  The slots for each have a similar difference in size. Obviously the slots need to be big enough to accept the correct card. Bonus tip. Download a pdf of your camera manual to your phone. Even better some companies (for example Nikon) have phone apps to store your manuals on the phone. It can happen that a you won’t remember a little used command. Situations like this often happen at odd hours far from home and your printed manual.

Speed and how much you need

4K requires more speed when compared to HD. But it doesn’t actually require the fastest cards. Currently the latest card standard is uhs-ii. It’s unlikely you will need these cards. Your camera is unlikely to even support these cards. Once again your manual should mention if your camera supports these newer expensive cards.

What you do require is sd card class 10 uhs 3. The important bit is the UHS 3 part.  The problem here is the one things the companies almost hide is the 3. When you look at the image of the card you’ll see a large case U with a number inside the U. What you’re looking for is the 3. If you see an 1 keep looking.  BTW if the card doesn’t list class 10 don’t even bother looking for the U. Older class cards won’t keep up. Class 10 UHS 3 . Remember that.

You will see cards advertising transfer speeds. These speeds are in MB which means megaBytes. Your camera will advertise a recording rate in Mb aka megaBits (note the lower case b). It might be 60mb,100mb  or even higher. A common mistake people make is confusing MB with Mb. One byte is eight bits.. A camera that records at 100Mb is only recording in 12.5MB.

How large?

This is a bit tricky. Different cameras record at different bit rates which leads to different file  sizes. Different people film in different ways. If you’re recording a long event (A concert for example) you’ll want a card large enough to last the whole event or at least until a planned intermission. If on the other hand you’re recording short fifteen second clips all day long you can easily change cards when the first one fills up.

Go back to your user manual and check the file sizes for your camera.


Estimated recording time of movies

The webpage in the above link is for a small Sony action camera. You’ll see mention of 75 minutes on a 64GB card. That means for a two hour concert you’d need either an 128GB card or enough smaller cards totally 128GB.

Like batteries it’s better to have too many cards . Bringing home an extra unused card won’t upset you. Missing an important moment because you had filled up all your cards will.


If you’ve read this far one last bit. I’ve intentionally left out XQD and CFast cards. If your camera uses these cards the same basic principles are important. Just remember RTFM.