How To Choose SD Card: SD Card Speed Classes, Grades & Capacities explained

How To Choose SD Card for smartphone camera

How To Choose SD Card

These days every individual holds a smartphone or a gadget. With excessive use of apps, games, and movie making inbuilt memory  SD Cards Commonly used to expand the storage in devices ranging from smartphones to drones and DSLR cameras.

SD, SDHC, and SDXC all physically look the same, therefore they’ll all fit in a regular SD card slot. Devices are backward compatible, so an SDXC-compatible device can use SDHC and SD cards. An SDHC-compatible device can use SDHC and SD cards, but will not be able to use SDXC cards.

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microSD: Max storage of 2GB, transfer rate of 25MB/s — uses FAT12, FAT16 or FAT16B file systems

microSDHC: 4GB to 32GB of storage, transfer rates from 50MB/s — typically uses FAT32

microSDXC: 64GB to 2TB of storage, transfer rates from 50MB/s — uses exFAT

Here’s a quick overview of the different SD card sizes:

Standard SD cards: SD (SDSC), SDHC, SDXC, SDIO — 32 x 24 x 2.1-1.4mm
miniSD cards: miniSD, miniSDHC, miniSDIO — 21.5 x 20 x 1.4mm
microSD cards: microSD, microSDHC, microSDXC — 15 x 11 x 1mm

SD card speed classes explained

The SD Association has standardized the speed ratings for different cards. These are defined as ‘Speed Class’ and refer to the absolute minimum sustained write speeds.

Cards can be rated as Class 2 (minimum write speed of 2MB/s), Class 4 (4MB/s), Class 6 (6MB/s) or Class 10 (10MB/s). These are the minimum speed. So it’s entirely possible a card can achieve faster speeds but these give you an impression of the least you can expect.

sd card speed class

Many SD card manufacturers will also list a specific speed alongside the Class rating. This means a card can be Class 10 but also be listed as ‘up to 80MB/s’. You might also see a description such as ‘533x’. This refers to a multiplication of the speed of an old CD-ROM (150KB/s). So in this case 533 x 0.15 = 80MB/s. On any type of SD card, the Class rating is denoted by a number inside of a C symbol.

SD Speed Class/UHS Speed Class/Video Speed Class

There are three kinds of Speed Classes, “Speed Class”, “UHS Speed Class” and “Video Speed Class.”

SD Speed Class UHS Speed Class Video Speed Class (1)

As a characteristic of flash memory, actual transfer speed varies. Variable speeds are difficult to reliably record streaming because it requires a constant writing speed. All Speed Classes provide the constant speed necessary for video recording.

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SD Standard for Video Recording

When buying an SD card, you’ll need to buy the right speed class, size, and capacity for your needs. Be sure to check what your device supports and consider what speed and capacity you’ll actually need.

SD, SDHC, SDXC, and SDUC Card Capacity Choices

SDUC memory cards must only be used with SDUC Host Devices.

  • SDXC memory cards can be used with SDXC devices and SDUC Host Devices.
  • SD Host Devices can only use SD memory cards.
  • SDXC Host Devices can use SD memory cards, SDHC memory cards, and SDXC memory cards.
  • SD memory cards can be used with SD devices, SDHC devices, SDXC devices, and SDUC Host Devices.

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  • SDHC Host Devices can use both SD memory cards and SDHC memory cards.
  • SDHC memory cards can be used with SDHC devices, SDXC devices, and SDUC Host Devices.
  • SDUC Host Devices can use SD memory cards, SDHC memory cards, SDXC memory cards, and SDUC memory cards.

Application  Performance Class for Running Smartphone Apps

With the expanded usage of SD memory cards for storing applications, photos, and image data, there is a growing need for the best memory card to run smoothly.

The SD Memory Card Formatter was created specifically for memory cards using the SD/SDHC/SDXC standards.

This table describes the Application Performance Class 1 (A1) and Class 2 (A2) specifications. It describes the minimum random read performance inputs/outputs per second (IOPS), minimum random write performance (IOPS) and the minimum sustained sequential performance (MB/s) of the corresponding SDHC/SDXC Memory Cards under the conditions defined in SD 5.1/SD 6.0 Part 1 Physical specification.

best sd card fro smartphones (1)

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