If you are thinking of buying an SD or micro SD card and have looked online you will have realized the large amount of products on the market. So how to choose a memory card and understand how fast it is ?
For this purpose, there are different classifications adopted by the SD Association , the consortium that includes the main producers, which allow the user to understand the performance of a ticket with relative ease. So let’s see how to interpret the acronyms that define SD and micro SD cards .
Division into “Classes”: speed Class 2, Class 4, Class 6, Class 10 (C2, C4, C6, C10)
Let’s start with the oldest classification, that is the one that uses the name “Class” followed by a number. This is very easy to interpret as you just have to take the name that follows “Class” (in the contracted form “C”) and write it in MB / s.
- Class 2 (C2):2 MB / s
- Class 4 (C4):4 MB / s
- Class 6 (C6):6 MB / s
- Class 10 (C10):10 MB / s
This is the minimum write speed value guaranteed by the manufacturer and the SD Association providing the standard. With this data you can then choose the SD or micro SD card that best suits your needs.
UHS classification: U1, U3, UHS-I and UHS-II
To meet the growing needs of videomakers and more generally of increasingly performing devices, SD and micro SD devices have been brought to the market with ever greater speeds. For this, an additional standard called UHS was created .
This has only two entries U1 and U3 , respectively for minimum write speeds of 10 and 30 MB / s. Another important aspect of the UHS standard is that it refers to the bus of the same name (hardware component that manages data exchange).
It is not uncommon to see signs such as UHS-I or UHS-II among the features of a card . This indicates the type of UHS bus , which allows (on devices compatible with UHS-I or UHS-II) writing speeds of up to 104 MB / s and 312 MB / s respectively.
Video Speed Class: V6, V10, V30, V60, V90
In 2016 , another standard was introduced , called Video Speed Class . This, similar to the first classification, clearly shows the writing speed thanks to a V followed by the digit. Just the number indicates the minimum writing speed:
- V6:6 MB / s
- V10:10 MB / s
- V30:30 MB / s
- V60:60 MB / s
- V90:90 MB / s
SD A1: cards for apps and games on smartphones
Among the younger standards also SD A1 and A2, or Application Performance Class 1 or 2 . These are terms explicitly dedicated to Android smartphones (therefore to micro SD ), those where it is possible to install apps and games even on external memory. In fact, these standards indicate that the card offers a high number of read and write IOPS , i.e. operations performed per second. With the latest generation memories , therefore the A2 , we are talking about 5,000 IOPS in reading and 2,500 IOPS in writing.
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How to choose SD and micro SD: full HD (1080p), 4K, apps and games
Ok, we figured out how to broadly frame the performance of an SD or micro SD card, but how do we figure out which one is actually suitable for our purpose? The first thing to do is figure out what we need the card for.
For example, if you use it for simple storage, you can aim for a card that is not too perforating (a Class 10 now costs very little), while if your video / camera runs in 4K or you intend to use the micro SD on an Android smartphone, even for apps and games, you should aim high.
To get an idea, inquire about the maximum bitrate (in MB / s) of your recording device and choose the SD / micro SD based on that. Also keep in mind that beyond the standards any SD card can offer speeds that go well beyond the guaranteed minimum. Always check the product description and look for hand evidence online.
