What SD card should I buy for my cell phone: speed, capacity, etc.

To find the ideal external memory card for a cell phone, you have to look at a few things. The most important are size, capacity and speed. Manufacturers use various terms and numbers in their products, it helps to know what they mean in order to choose the most appropriate option.

Size

There are SD cards of various sizes: SD, mini SD and micro SD. The explanations below apply to all of these card formats, but today’s mobile devices often use micro SD.

Ability

The first thing is to find out what external storage capacity the phone supports. Depending on this value, which can be seen in the technical specifications of the equipment, you can put an SD card of equal or lesser capacity. It is not recommended to put a card with a higher capacity than the one supported by the phone.

For example, if the phone supports 64 GB maximum, you can put a card of 64 GB, 32 GB, 16 GB or even smaller capacity cards.

Cards have been given a “name” based on their capacity range (1):

SDSC (or simply SD): 128 MB up to 2 GB.
SDHC: 4 GB hasta 32 GB.
SDXC: 64GB up to 2TB.

For example, a 16GB SD card will have the SDHC name indicated on the outside as well as on its box. A 128GB card will have the name SDXC.

Velocity

This is one of the most technical aspects. Speed ​​refers to the time it takes to open files or applications (read speed), or how long it takes to install an app or save a video that is being recorded (write speed). SD cards are generally marketed based on the minimum write speed they offer:

Class 2: 2 MB / s
Class 4: 4 MB / s
Class 6: 6 MB / s
Class 10: 10 MB / s
UHS 1: 10 MB / s
UHS 3:30 MB / s

The higher the speed, the better.

There is another category of speed called “Video” that can offer minimum write speeds of 10, 30, 60 or 90 MB / s, but it will not be considered in this article because it is not very common.

This is a rating based purely on typing speed. The reading speed of each category is usually much higher.

What card speed do I need?

The decision usually comes down to what the user does with the device’s camera. Depending on that you must choose a card of a certain class. A higher speed card can have a positive impact on other tasks, as mentioned above, but the use of the camera is the critical point.

Class 2 is recommended for low resolution videos. Class 4 and Class 6 are for HD photos and videos and scratches in Full HD. Class 10 and UHS 1 are recommended for recording video in Full HD. UHS class 3 is recommended for 4K video recording. Higher speed ensures that large files, such as 4K videos, are recorded correctly.

Updated January 14, 2017: Review this article where the difference is explained real between a Class 10 card and UHS in a smartphone.

Certainly, a UHS 3 card is the best, but not necessarily the most recommended in all cases. First of all, it is more expensive than lower speed cards. Second, it is necessary for the mobile device or camera to support this UHS 3 technology to exploit its full performance. Third, if the user usually prefers to record videos in Full HD to save storage space, it would be a waste to choose a UHS 3 card that has a superior approach. (2)

A faster card is needed if the cell phone has problems taking photos or recording video. For example, when things like the camera app freeze after taking a photo, the video files are corrupted, the video recording stops abruptly, or the burst mode does not work properly (3).

Additional notes

UHS I and UHS II

While UHS 1 and UHS 3 above specify the minimum speed of a card, SDHC and SDXC, UHS I and UHS II define the maximum speed (this last word is key) on these same cards. UHS I can offer a maximum speed of 104 MB / s, while UHS II offers 312 MB / s. These values ​​are purely theoretical and in practice they are not reliable. Such figures say that a UHS II is faster than a UHS I card, but in reality this may be the other way around. A clear example of this is the micro SD card Lexar Professional UHS II (UHS 3) and Samsung PRO Select UHS I (UHS 3 too). The Samsung UHS I offers twice the speed of writing on paper.

For this reason it is important to refer to the manufacturer’s specification to determine the actual values. Similarly, the device must be verified to support the same maximum card speed to obtain full performance.

A UHS II card can work in a UHS I device or even one that does not support UHS.

Difference between Class 10 and UHS 1

In practice, both are the same. The maximum theoretical values ​​of one and the other may be different, but as before, it will be necessary to refer to the manufacturer’s specification to compare.

A UHS 1 card can work in a device that only supports Class 10. In fact, many UHS 1 cards also often carry the Class 1 label, indicating backward compatibility.

Example

The Samsung EVO Select micro SD card in this link It says the following on the outside: SDXC, 64, 1, I. Its 64GB capacity is in the range of an SDXC card (64GB – 2TB). The number “1” refers to UHS 1. This means it must have a minimum write speed of 10MB / s. And the manufacturer confirms it: it indicates that it has a write speed of 20 MB / s. The letter “I” refers to UHS I, which means that it can reach a maximum transfer speed of 104 MB / s. Being maximum, it means that the read and write speed may be below that value. And just that happens: the 20 MB / s of writing speed and 80 MB / s of reading correspond to this specification.

More information: Wikipedia (it is), Electric hacker

How to know which micro SD my cell phone supports?

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