If you are thinking of purchasing an SD or micro SD card and you 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 several classifications adopted by the SD Association, the consortium that includes the main manufacturers, which allow the user to understand the performance of a coupon with relative ease. Let’s go to see how to interpret the acronyms that define the SD and micro SD cards.
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 it is enough to take the name that follows “Class” (in the contracted form “C”) and report it in MB / s.
This is the minimum write speed value guaranteed by the manufacturer and the SD Association that provides the standard. With this data, you can then choose the SD or micro SD card that best suits your needs.
To meet the growing needs of videomakers and more generally more and more high-performance devices, SD and micro SD cards have been brought to the market with ever increasing speeds. For this, an additional standard called UHS has been created.
This has only two voices 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 the exchange of data).
It is not uncommon to see among the characteristics of a board such as UHS-I or UHS-II. 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.
In 2016, an additional standard was introduced, called Video Speed Class. This, like the first classification, clearly shows the writing speed thanks to a V followed by the digit. Just the number indicates the minimum writing speed …
Among the younger standards also the SD A1 and A2, or Application Performance Class 1 or 2. These are words explicitly dedicated to Android smartphones (therefore to micro SD), those where you can install apps and games also on external memory. In fact, these standards indicate that the card offers a high number of IOPS for reading and writing, that is operations performed per second. With the latest generation memories, therefore the A2 , we speak of 5,000 IOPS for reading and 2,500 IOPS for writing.
Ok, we understand how to frame the performance of an SD or micro SD card, but how can we figure out which one is actually suitable for our purpose? The first thing to do is to understand what we need the card for.
For example, if you use it for simple storage, you can point to a not too perforating card (now a Class 10 costs very little), while if your video / camera runs in 4K or you are going to use the micro SD on an Android smartphone, also 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 according to that. Also keep in mind that beyond the standards every SD card can offer speeds that go well beyond the guaranteed minimum. Always check the product description and look for hand tests online.
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