Micro SD Memory Cards: Difference between Class 2, Class 4, Class 6 and Class 10

Looking for a suitable microSD memory card for my smartphone in the Amazon offers, I came across the terms Class 2, Class 4, Class 6 and Class 10 according to which the different memory cards were classified.

Up to now, I have never heard about such classes. If someone feels the same way, here is the necessary information:

• Class 2: minimum of 2 MB/s (16 Mbit/s)
• Class 4: minimum of 4 MB/s (32 Mbit/s)
• Class 6: minimum of 6 MB/s (48 Mbit/s)
• Class 10: minimum of 10 MB/s (80 Mbit/s)

The classes are an indication of the minimum speed with which you can write or read the memory card. The higher the class is, the faster information can be written to the card. Therefore, for example, you can write at least with 4 MB per second from a microSD card of Class 4.

Cases in which a higher class is better

Depending on how you want to use your card, the highest possible class or a lower class can be worthwhile.

For example, if you would like to record high resolution videos or many photos in quick succession and store them on the microSD simultaneously, the highest possible speed class is recommended, because - of course - the next picture can only be stored after the last one was saved.

The same applies to the reading of information. If you want to look at, for example, a high definition video that consumes 4 MB per second, you cannot succeed with a Class 2 Micro SD.

Cases in which a lower class is better

The specification of the writing speeds and reading speeds always refers to a sequential access, that is, the data is simply written or read consecutively.

However, a disadvantage of the higher classes is that this decreases the speed of the random access to a desired point on the card. This is especially important if you want to outsource some apps to your memory card, for example. Therefore, for this purpose, you should better use a lower class such as a Class 2 card instead of a Class 4 card.

Micro SD, Micro SD HC, Micro SD XC und Micro SD UC

Apart from the distinction of different speeds, there is also a difference between Micro SD, Micro SD HC, Micro SD XC as well as Micro SD UC flash memory cards.