How to: Choose the Right SD Card

Dear App Store,

I have a confession to make. You thought I’d be loyal to a few core apps, but in reality, I download and delete all the time. I’m curious. I want to explore all the options out there. It’s just, there’s never enough space in my phone’s memory. I even tried to get an SD card, but there are so many different types, it’s hard to know which one to buy…

Until now.

Confronted by the huge wall of SD cards at the store, or the ever expanding choices online? Here’s your SD card primer.
sd cards
First, SD cards are divided by type, class, and storage capacity.

When do you need a regular SD card?

The size of SD card you’ll need is generally indicated on the device. However, as a general rule, bigger devices use bigger cards. For example, both my Panasonic point-and-shoot camera and my spankin’ brand new Nikon DSLR use regular-size SD cards. Be aware, though, that your device (especially if it’s older) may not support SDHC or SDXC cards. It’ll say if it does, either in the instruction manual or on the side of the device.

When do you need a mini SD card?

I personally have never had a device that requires a mini SD card. However, some of the older cellphones out there accept them.

When do you need a micro SD card?

Now, this is what you came here for. Nearly all smartphones nowadays have a micro SD slot. There are, of course, some that don’t–Apple’s iPhone does not have an SD card slot, and neither does the HTC One–and some people argue that they aren’t even necessary. However, if you have anything lower than a high-end smartphone, it is quite possible that you need a little extra storage space for all those apps, music, and data you’ve got stored on your phone.

At the moment, these “micro” memory cards are the smallest available. Can you imagine? A long, long time ago (or not so long ago for some), personal computers were sold with a mere 2 KB of hard drive memory! And now? We’re talking about micro external memory cards that hold up to 2TB–you should be impressed, I tell you.

The Types

Besides the physical size of the card, Secure Digital (SD) cards are also divided into types: SD, SDHC, and SDXC. These different names really indicate the potential storage capacity of the cards, as well as the read/write speed. Regular SD cards are small, about 2GB. The SDHC card ranges from 4-32 GB in storage capacity, while the SDXC card (a high-performance version of the SDHC card) ranges from 48 GB and above.

SDHC cards are cheaper than the SDXC type, which makes them a good option for mid-range smartphones and below. However, the SDXC format was designed to meet the speed and performance requirements of high-resolution DSLRs and video cameras. As such, if you need to expand your storage capacity for a high-end smartphone that you use regularly for taking photos and video, it may be recommendable to invest in a SDXC card rather than the normal SDHC type.

The Classes

sd classes
Classes are numbered, ranging from 2-10 depending on read/write speeds. Prices vary widely according to the class number and the MB desired (and the brand–remember, you pay a premium for that fuzzy feeling of brand security). Mostly, prices change depending on the class number, since a higher class means that the SD card boasts faster processing capability and thus ends up more expensive than its slower counterparts. But wait! Don’t leave and feel like you’ve got to buy the most expensive card out there!

In simple terms:

Class 2: (2 MB/s)
Only used in standard quality recording.  I don’t think that anyone should buy a class 2 card for any kind of device. (Except, of course, for the one I bought for my first digital point-and-shoot camera and still use more than 7 years later….)

Class 4 & 6: (4 & 6 MB/s)
It records video in High Definition and Full HD. There is definitely a big step up from the Class 2 cards. You should get one of these for your smartphones, since most of them have the option to record in HD and they also take high definition pictures. Between these two, there’s not much of a perceivable difference if you use it for your smartphone. I generally use class 6 since the performance is a bit better and prices are not that different from the class 4’s.

Class 10 (10 MB/s)

They are generally used in DSLR cameras and they are more expensive than the class 6. (by almost double). If you want the best of the best you could get one for your smartphone but it’s not really worth the money since you won’t be able to notice it. Do get this for your DSLR camera, though.

Finally make sure that your smartphone is compatible with certain cards, almost all are compatible with Class 4’s but not all are compatible with 10’s–especially the older smartphones.

What You Should Do

raining numbers
So which SD card should you get for what?

Obviously, the physical size of SD card is determined by the device. If your device calls for a micro SD card, you can’t go out and buy a regular-sized card and expect it to fit. Look inside the device or its manual. The type will be specified there.

As for everything else, we’ve made a convenient table with recommendations:
sdcards table
That is, first determine what physical size you need for your device. Then, if you need the card for taking high-resolution photos and video, you may want to choose a SDXC type. Otherwise, get a SDHC card. And lastly, depending on your needs, find the class number you should get based on the table above.