Most often, SD cards are used to expand the available memory of smartphones, tablets, drones and other devices, and among all existing types of flash drives, microSD is especially popular. Although full-featured SD is still actively used by owners of digital cameras and cameras.
What are SD cards :
- standard SD: SD (SDSC), SDHC, SDXC, SDIO - 32 x 24 x 2.1-1.4 mm
- miniSD: miniSD, miniSDHC, miniSDIO - 21.5 x 20 x 1.4 mm
- microSD: microSD, microSDHC, microSDXC - 15 x 11 x 1 mm
In addition, relatively recently, the SD Card Association introduced new formats of memory cards in the SD 7.0 and SD 7.1 specifications: SD Ultra Capacity (SDUC) with support for memory up to 128 TB and SD Express, in which the outdated interface is supplemented with PCIe 3.0 and support for NVMe v1.3 that allows you to get speeds of up to 985 MB / s while maintaining backward compatibility.
Just imagine a situation in which all your devices will have NVMe solid-state drives instead of outdated sluggish interfaces. They boast a high speed equivalent to many SSDs, so SD Express cards will be similar in their functionality to solid-state drives. In addition, support for PCI Express and NVMe can increase the speed of data transmission while ensuring backward compatibility.
Every year, the cameras used by mobile devices only get better, games are bigger, and complex desktop programs can already be run on tablets and smartphones. All this means an increase in demand for faster and more capacious flash drives. Cards microSD Express, which should appear on sale very soon, will have the same or slightly less power than what offers already existing options on the market. But they can guarantee that their maximum energy consumption will be at or below what was achieved by previous generations.
Read more about microSD
It is worth noting that in this guide we will consider microSD cards, but most of the information will help when choosing a flash drive of any other form factor. The SD Association approved the final microSD specification as early as July 2005, when their memory did not exceed 128 MB. Later, we managed to get rid of the limitation and more spacious SDHC and SDXC appeared on the market.
- microSD: memory up to 2 GB, data transfer rate from 25 MB / s - use FAT12, FAT16 or FAT16B file systems.
- microSDHC: memory size from 4 GB to 32 GB, data transfer rate from 50 MB / s - usually use the FAT32 file system.
- microSDXC: memory capacity from 64 GB to 2 TB, data transfer rate from 50 MB / s - use the exFAT file system.
As we have already noted, most of the SD cards available today on the SD card market have the microSD form factor, and the vast majority of them have the microSDXC specification. This means that they are much easier to find and buy.
MicroSDXC cards can be divided into several categories, depending on the speed of data transfer. In the future, this information can be applied to all flash drives of the SD family from those that we mentioned above.
The SD Association has proposed several different speed classification systems that will help determine which cards are best suited for a particular purpose.
The “Speed Class” column is the most important indicator that reflects the direct data transfer rate of SD cards. For example, Class 2 drives (at a speed of 2 MB / s) are best suited for working with standard definition video, while Class 10 cards (at a speed of 10 MB / s) are capable of recording and playing video in up to 4K format.
In addition, for some SDHC and SDXC cards, Ultra High Speed (UHS) is used. There are three UHS classifications (UHS-I, UHS-II and UHS-III). Each introduces a variety of progressive solutions that allow you to increase the speed of data transmission.
For example, the version of UHS-III v6.0, released in February 2017, includes two new full-duplex specifications. While the UHS-I has a 104 MB / s limit and the UHS-III has a maximum throughput of 624 MB / s with full-duplex, the UHS-II can transfer data to and from the card. 156 MB / s using half-duplex or 312 MB / s with full-duplex.
The classification established by the organization “Video Speed” gives brief information about the cards: for example, the “Video Class 10” indicator includes cards with a minimum sequential write speed of 10 MB / s. Video Class 90 cards (V90 at 90 MB / s) support recording and playback of video with a resolution of 8K at 60 or 120 frames per second.
последовательной записи Minimum sequential write speed
|UHS speed class||Video Speed Speed Class Video Speed|
нагрузка Optimal load
|Class 2 (C2)||2 MB / s||Record and play at standard resolution|
|Class 4 (C4)||4 MB / s||720p / 1080p video|
|Class 6 (C6)||6 MB / s||Video Class 6 (V6)||720p / 1080p, and 4K video|
|Class 10 (C10)||10 MB / s||UHS Class 1 (U1)||Video Class 10 (V10)||720p / 1080p / 4K video|
|30 MB / s||UHS Class 3 (U3)||Video Class 30 (V30)||1080p / 4K video at 60/120 fps|
|60 MB / s||Video Class 60 (V60)||8K video at 60/120 fps|
|90 MB / s||Video Class 90 (V90)||8K video at 60/120 fps|
The relatively new classification of SD cards “Application Class”, which was not included in the table, has two classes: A1 and A2, which reflect the minimum performance of the cards in IOPS. A1 standard cards are well suited for reading in 1500 IOPS and writing 500 IOPS, while A2 increases these figures to 4000 IOPS and 2000 IOPS, respectively.
In addition, if you see an SD card with an A1 or A2 stamp, you can be sure that this drive is capable of providing a consistent sequential write speed of 10 MB / s.
|Class||последовательной записи Minimum sequential write speed||Minimum random read speed||Minimum random write speed||Optimal load|
|A1||10 MB / s||1500 IOPS||500 IOPS||Not only data storage, but also editing, updating|
|A2||10 MB / s||4000 IOPS||2000 IOPS||They are more productive and suitable for special use.|
Of course, do not forget that the faster the card, the more expensive it is. Therefore, it makes sense to pre-determine their needs. If you are a professional in photography, you will need a higher-performance card than the average user can afford. If you plan to use it for the banal expansion of memory in a budget smartphone, then it is quite possible to do with a simpler option.
And although the main purpose of this article is to provide you with all the information you need to purchase a micro SD (or full-size SD) card, then we will tell you about several flash drives, each of which is ideally suited to perform certain tasks.
The best ratio of price and quality
- The best price-performance ratio is the Samsung Evo Select 64GB U3 (about $ 11), followed by the Samsung Evo Select 128GB U3 (about $ 20), featuring a higher capacity.
If you recently updated your PC and chose an SSD for it, you probably noticed that in recent years a huge number of various Samsung drives have appeared. Therefore, it is likely that you decide to install their branded microSD in your smartphone. One way or another, one should not be surprised at the presence of the brand in the market. Moreover, at the moment Samsung produces the best microSD
For only $ 11, the Samsung Evo Select with a capacity of 64 GB offers a speed of 100 MB / s when reading and 60 MB / s when writing. The card comes with an SD adapter, and by the end of 2018, it was one of the best-selling on Amazon. If 64 GB is not enough for you, then pay attention to the Samsung Evo Select with a capacity of 128 GB. The model offers the same read speed, but faster write speed (up to 90 MB / s). Consider that the Samsung Evo Select 128 GB will cost a bit more expensive than the 64 GB option, its average cost is about $ 20.
Of course, in this price segment there is a huge number of alternatives. But be careful when buying a microSD with a classification of U1. Most of them have the same reading speed as Samsung’s cards, but lower write speeds (around 20-30 MB / s).
Most high-performance microSD
- For tablets and smartphones - SanDisk Extreme 128GB U3 / V30 A2 (about $ 30)
- For digital cameras and video recording - Delkin 1900x 64GB UHS-II U3 / V60 (about $ 85)
- Alternative - Samsung Evo Select 128GB U3 (about $ 21)
For everyday use in any budget smartphone, almost any microSD from the middle price segment will do. Such cards, as a rule, have a rather large capacity and high speed of writing, reading data. If you are looking for microSD to perform any specific tasks (for example, 4K video recording), then make sure that the drive meets all the necessary requirements. To do this, do not forget to use the table above.
If you are looking for a memory card for a smartphone or tablet, then you should pay attention to the fact that microSD has fast random access to read small files. SanDisk Extreme 128GB (SDSQXA1-128G-GN6MA) boasts a sequential write speed of 90 MB / s and read speed of 160 MB / s. Of course, this is not about permanent, but about peak indicators. More importantly, SanDisk Extreme 128GB has a high speed of random write and read operations.
To record video using drones or any other video equipment you will need a card with the highest rating (UHS-II V90). However, they are not available in the microSD form factor. Next come the UHS-II V60 drives, providing a stable read speed of 60 MB / s. Cards Delkin MicroSDXC (UHS-II U3 / V60) boasts a read speed of up to 300 MB / s and write up to 100 MB / s. Lexar Professional from the 1800x and 1000x series are also considered good ones. In order to use the capabilities of these cards to the maximum, make sure that the microSD slot of your device supports UHS-II.
Finally, if the high performance of the card is of paramount importance to you and at the same time the device supports full-sized SD cards, then instead of microSD with an adapter, it is better to use a full SD. The most high-performance SD cards are produced by Sony and Lexar. On average, their reading speeds can reach 300 MB / s.
Most spacious microSD
- Largest capacity - Kingston Digital Canvas React 512GB U3 / V30 A1 (about $ 150)
- Large capacity and high speed - SanDisk Extreme 400GB U3 / V30 A2 (about $ 110)
Kingston, Micron and Sandisk offer microSD cards with the largest capacity available on the market today. Until the second half of 2019, their maximum capacity can reach 1 TB. The Kingston “Digital Canvas React” series boasts cards with a capacity of up to 512 GB. In addition, since the release of their value has fallen dramatically, and now this card can be purchased for only $ 150. PNY offers a similar variant in capacity, although their 512 GB microSD card will cost a little more (about $ 190).
The maximum capacity of cards from SanDisk is 400 GB, while other brands rarely boast 256 GB. SanDisk Extreme UHS-I microSD memory cards with a capacity of 512 GB and 1 TB will go on sale in April 2019, the cost of MSRP should be about $ 200 for a variant with 512 GB and $ 450 for a model with a capacity of 1 TB.
In terms of price and data reading / writing speeds (100 MB / s for reading and 80 MB / s for writing), the Kingston memory card is just between alternative recommendations, while SanDisk Extreme 400 GB can be called the best option. for those who really care about speed. This is practically the same card as the higher version, but with a higher capacity and peak write speeds of 160 MB / s, 90 MB / s reads and a unique A2 rating.