Understanding SD Cards (Part 2)

Different devices call for different types of SD cards. If you ever have tried to buy one online or at a store you know there a lot of different sizes, speed and capacity. Each size can have different speeds and different capacity making it very confusing. Let’s look at the differences.

Size

(REMEMBER: SD cards will only work in matching size slots. They do make adapters so that mini/micro cards can be used in a standard SD card slot.)

Standard SD cards are the largest and most common at 32 x 24 millimeters and 2.1 millimeters thick. These are common in digital cameras.

MiniSD cards are less common. They measure 20 x 21.5 millimeters and 1.4 millimeters thick. These were common in older mobile phones, but have been falling out of use.

MicroSD cards are the smallest of the bunch at 15 x 11 millimeters and 1 millimeter thick. These cards are used in most smartphones and tablets.

Speed

Not all SD cards offer the same speeds. This is not important if you’re just using the card to store some photos or word documents. However, if you’re using an SD card to record HD video, speed is very important. You'll find the logo for the speed next to the SD card's logo. It’s a number inside a circle (see the example above).

There are 4 different common speed classes, each associated with a number: 2, 4, 6, and 10. Class 2 is the slowest speed while class 10 is the fastest. Class 2 cards are typically used for standard video recording and data storage. Class 4 or 6 can be used for HD photographs and are commonly found in smartphones and digital cameras. Class 10 is the fastest speed, and these cards are typically used for recording full HD videos.

Capacity

SD stands for Secure Digital. This is standard format and the card will typically hold up to 4 GB of data. This capacity is available in all 3 sizes.

SDHC stand for Secure Digital High Capacity. This format will hold from 4 GB to 32 GB of data. This capacity is available in all 3 sizes.

SDXC stands for Secure Digital Extended Capacity. This format will hold 32 GB to 2 TB of data. This capacity is only available in Standard and Micro sizes.

When purchasing a SD card, it’s important to check with the manufacturer of your device to make sure you get a memory card that supports and works with your device. Thanks to their small size and durability, SD cards are perfect for transferring or backing up data. The one down side is their size: because they’re so small, they’re easily lost. So keep an eye on where you put them.