SD cards are simple tiny storage devices that can help you store your multimedia and documents on them. You may use them to expand the storage on your phone or to take stunning pictures with your DSLR. They are available in various sorts and sizes. You may have encountered a situation where two identical SD cards with the same storage capacity were being sold at diabolically different costs while you were purchasing a new SD card. Similarly, at times your device might have prompted you about the incompatibility of your card even though it’s within its storage limit. In this post, we’ll go into great detail regarding the precise characteristics of an SD card to help you grasp this.
We will use the image of a Prograde SD card to understand the meaning of different numbers and letters. This format is standard throughout the industry.
SD card type
Look at the bottom left of the image. It mentions SDXC. These letters represent the type of card. Mainly there are three kinds:
- SD [Secure Digital] They range in size from 64MB to 2GB and use the FAT12 or FAT16 file system.
- SDHC [secured digital high capacity] They range in size from 4GB to 32GB and use the FAT32 file system.
- SDXC [Secure digital extended capacity] These are the most advance of all. They range in size from 64GB to 2TB and employ the exFAT file system.
Storage capacity
This is something always written in bold and big fonts. From the given image it is clear that the storage provided for that particular card is 256 GB. This gives you the precise number rather than the range you get from the letters.
Read and Write speed
On the right side, two numbers are mentioned each leading with a letter. The one leading with R represents the read speed of the SD card and the one leading with W represents write speed. They are represented in MB/s which stands for Megabytes per second. Read speed tells us how fast you can transfer your files. On the other hand, write speed gives information about how fast will you be able to work on files stored in your SD card.
Bus interface
It is the one mentioned at the bottom of the card. It essentially tells you the fastest bus speed that your card can transfer data. Ultra High Speed is referred to as UHS.
UHS-I or UHS-II bus interfaces are used in almost all SD cards produced today. Roman numerals I and II are used on the card to designate them.
UHS-I allows a maximum of 104 MB/s while UHS-II supports data transmission rates of up to 312MB/s. Previous standards are all no longer applicable because their maximum data rate is 25MB/s.
In UHS-I-compatible devices, UHS-II cards can be used, although they won’t operate as quickly.
Now let’s take a pause as you have gone through few features of SD card and see ranges of Prograde’s SD cards available on Amazon. Here is the link, you can follow to purchase any of the Prograde SD card.
Speed class rating
This is an important rating for people who are in video making process. Your card must contain a certain amount of rating to avoid frame drops while recording. In simple terms, if you are looking to shoot video in 4K then you will need a higher speed class rating SD card.
As we can see in the image three different speed class ratings. The one with a number and letter “c” is called speed class rating. Here 10 represents a write speed of 10 MB/s. The second rating is displayed with a number inside the letter “U”, in our case the number is 3. It is referred to as UHS speed class You need to multiply that number by 10 to get the write speed. Hence it is 30MB/s. And finally, the Video speed class is represented by a number with the letter “V”. The number directly corresponds to the write speed.
To understand better how these speed classes relate to each other, below is the image showing the comparison.
Conclusion
Next time while buying an SD card look out for these numbers and letters. It is not just the storage capacity but read and write speed, speed class rating, etc which determines its cost and usage. If you are looking for a solution to simply store your data consider reading our article on “SSD vs HDD“.