A Guide to Selecting an SD Card
People who are familiar with personal computers from the 1980s will remember large, square 5.25” floppy disks. They had enough capacity for around 500 KB or 1.2 MB of data. As hard as it is to believe nowadays, they were practically the only way to get information out of and into your computer! But they were very sensitive, and it was very easy for something to happen to the disc that you’d lose all your data. Touching the exposed part of the disc was a no-no. Exposing it to heat or a magnetic field would also destroy it. These floppy discs used magnetic storage, which was very volatile.
But nowadays, we have devices like USB thumb drives and SD cards. They use flash memory, which is not sensitive to the surroundings. They can be exposed to magnetic fields, and your data is still safe. They can also be IPX8 waterproof, shock-proof, and temperature-proof. And the capacities are astounding: You can easily get SD cards that are 64 or even 128 GB of storage! They’re the way to go in storing photographs or video content. And they can be used to extend the storage in your cellphone, tablet, drone, GPS, laptop, security camera, or even game controller!
But there are a lot of specifications on these SD cards, and it’s worthwhile learning about them. It will help you choose the right SD card for your purposes, whether it’s just for backing up data, or if you need speedy data storage, like when recording video. You’ll be amazed at how a device so small can store so much information!
What can I use an SD card for?
An SD (=Secure Digital) card can be used for storing files, such as photos, videos, music, and documents.
What sizes of SD cards are there?
There are three main sizes of SD cards, that employ flash memory to store data:
SD cards: These measure 24 mm in width and 32 mm in length.
Mini SD cards: These measure 20 mm in width and 21.5 mm in length.
Micro SD cards: These measure 11 mm in width and 15 mm in length.
There are memory card readers that allow you to hook up the various types of memory cards to a computer via a USB port. For example, the Rocketek USB C Multi Card Reader is capable of reading SD, mini SD, micro SD, microSDHC, and more!
Rocketek USB C Multi Card Reader
Types of Sd Cards
Looking over the Best Reviews Guide of the best SD cards, we see lots of acronyms and specifications. Besides the different sizes that we mentioned, they differ in capacity and read/write speeds. There has been a gradual progression in SD cards, with each successive version being able to store more and more data:
SD card: These were the first SD cards, which can hold up to 2 GB of data, with FAT12 or FAT16 formatting.
SDHC (= Secure Digital High Capacity) card: These can hold up to 32 GB, and use FAT32 formatting. Also, they can hold individual files as big as 4 GB in size, which makes them good for recording video. An example is the SanDisk Extreme 16 GB SDHC Memory Card.
SanDisk Extreme 16 GB SDHC Memory Card
You’ll notice that the SanDisk Extreme is marked HC I, otherwise known as UHS-I (“Ultra-High Speed I”). There are now UHS-II cards, which can transfer data more quickly than the UHS-I cards. UHS-I cards will have one row of pins, while a UHS-II card will have two rows of pins, to allow for faster data transfer. An example is the Sony Tough High-Performance SDHC UHS-II Flash Memory Card. It has a read transfer rate of 300 MB/s and a write transfer rate of 299 MB/s.
Sony 32 GB UHS-II SDHC Flash Memory Card. Note the two rows of pins in the UHS-II card.
SDXC (= Secure Digital eXtended Capacity) card: These can hold more than 32 GB, and up to 2 TB! They employ exFAT formatting, which allows them to hold files even bigger than 4 GB in size. This is pretty much the upper limit of what you’ll see in stores at present. An example is the Vansuny 128 GB Micro SDXC Card. It comes with an adapter so that it’ll fit into card reader slots for SD-size cards. It has a read speed of 90 megabytes per second, and a write speed of 30 megabytes per second.
Vansuny 128 GB Micro SDXC Card
The Vansuny 128 GB microSD card is a UHC-I card. Just for sake of comparison, the PNY EliteX-PRO90 64 GB SD card is a UHC-II card, with a data read speed of 300 MB/s, and a data write speed of 280 MB/s. It is for use in cameras where you need UHD resolution, as in state-of-the-art DSLR and mirrorless cameras.
PNY EliteX-PRO90 64 GB SD card
SDUC (= Secure Digital Ultra Capacity): These are specialized memory cards that can hold as much as 128 TB. But they require special equipment to utilize such capacity.
CFexpress cards: There are also CFexpress (CompactFlash express) cards, which are primarily for use in cameras. They have much faster read and write speeds than the other SD cards. For example, the SanDisk Extreme Pro 64 GB CFexpress card can read data at 1500 MB/s, and write data at 800 MB/s.
SanDisk Extreme Pro 64 GB CFexpress card
What reviewers say
Here are some of the impressions of customers regarding their choice of SD card:
Insane increase in speed: A customer who upgraded to the SanDisk 32 GB Extreme Pro SDHC UHS-II card said that tasks of copying the 4K video content from an SD card went from 15-25 minutes down to as little as 1-3 minutes!
Durable: One customer said that they lost their Lexar Professional 32GB SDHC UHS-II card, and ended up finding it in their pocket–after it went through a washer and dryer! Not only was the data intact, but the user was also even able to copy all the data, format the disk, and use it again!
Here are some tips and features of SD cards that may help you make a decision when shopping:
Backward-compatible: With all of the constant improvements and upgrades, you have to be careful that a new SD card will work with your camera, tablet, or other devices. Typically, if your device can read an SDXC card, it can read the older formats as well (SDHC and SD). That’s backward compatibility: being able to accept the older versions as well. But, if your camera can only take an SDHC card, it won’t accept the next in line, the SDXC card.
Speed: We already mentioned the difference in data speeds between UHS-I and UHS-II. Note that if you use a UHS-II card on a UHS-I device, it will read at the slower, UHS-I speed! There are two other speed specs that are useful to know:
V30, V60, and V90: These are specs that indicate that the card, when used for video recording, can record at a minimum write speed of 30 MB/second, 60 MB/second, or 90 MB/second. They’ll be used in FHD and UHD recording.
A1 and A2: When you see this spec on an SD card, it will indicate how fast will it handle applications (with “A” standing for “apps”), when used in a smartphone or game console.
We went through the range of SD cards available on the market nowadays. With this brief intro to the various specs, you should be able to select an SD card that matches your devices, whether it’s a camera, tablet, game console, or laptop. There’s no point in suffering from slow data transfer on old SD cards. Upgrade to the newest equipment, and see how much more you can accomplish!