Class Rating in Memory Cards – ALL YOU NEED TO KNOW
This entry was posted in General, Others on by .

          Memory cards are one of the most popular storage device which are used in portable electronic devices like smartphones, digital cameras, portable gaming consoles(PSP, Nvidia Shield etc), MP3 players etc. The revolution in science and technology has made made the memory card into very small chip with greater storage capacity ranging from megabytes to 256GB. Its a great thing that 256GB of data is accommodated into such a small chip. Also the price of the memory cards are getting cheaper and cheaper. Memory cards are available in different model(MMC, SD, microSD, SDXC, SDHC etc) which can be used based on the device compatibility or requirement.

          Transcend, Kingston, Sony etc are some of the popular memory card manufactures. It is quite normal that we always go for buying the products with less price and we expect a decent quality. This thought might lead to performance degradation in the electronic devices. Consider the below image.

8GB microSD memory card
1. Class 2
2. Class 4

          Both the 8GB memory cards in the above image are from same manufacturer, but the price in different. The memory card at the right side will be costlier than the memory card which at the left on the image. The difference lies in the Class Rating on it. Class Rating is a measure of read write performance of which is specified at the top right corner of the memory card with a number enclosed in a circle. The performance of any storage device can be measured by its read write performance. i.e the speed at which the data is transferred to and from the storage device. In the case of memory card Class Rating specifies its performance. The electronic device which we use may give low performance if we are using memory card with lesser Class Rating than the specified one. But in most cases we are considering only the storage with not being aware of the Class Rating. This will lead to performance degradation of the electronic device which we are using.

An example situation where we get degraded performance

          Consider we have digital camera which is capable of recording FullHD video which will be stored in the memory card. While shooting, the digital camera will shoot the video and the data will be continuously be transferred from camera to memory card. Consider we are using memory card with Class Rating 2 which will not be sufficient for recording FullHD video. This is because Class Rating 2 memory cards have read/write performance of upto 2MB/s. But the digital camera will be recording(generating the data) the video at 6MB/s or even 10MB/s. Thus the camera cannot record the video properly due to the low performance memory card. This is the case of any electronic device which uses memory  cards. So always go for memory cards with better class rating which is meant for the device we are using.Below table shows the Class Rating and its corresponding application use.

Class Rating and their Applications

Class Rating
Class 2
      1.    SD video recording
Class 4
4 MB/s
      1.   High-definition video (HD)
      2.    Full HD video recording
Class 6
6 MB/s
      1.    High-definition video (HD)
      2.    Full HD video recording
Class 10
6 MB/s
      1.    Full HD video recording
      2.    consecutive recording of HD stills
UHS Speed Grade 1
10 MB/s
      1.    Real-time broadcasts
      2.    large HD video files          

              UHS are Ultra High Speed memory card which gives better performance and are usually used in Digital-SLR cameras.

Leave a Reply