Things to Look for Before Buying an SD Card

We all use SD cards every so often either in a smartphone, tablet, digital camera or other devices as additional storage. Not all SD cards are same. There are different types of cards available with different sizes, capacity, and speed too. So, how much do you really know about an SD card and numbers on it? Here we’ve explained what those numbers on the SD cards mean and what to look for before buying an SD card.


Physical Size

The physical size of an SD card has shrunk significantly over the years. The cards are available in different sizes like Standard or Full-size SD cards, Mini and Micro SD cards.

Standard SD card is the biggest in size and still used in laptops and most of the digital cameras. They weigh about two grams and measures 32x24x2.1 mm.

Mini SD cards are slightly smaller than Full-size SD cards and designed especially for small mobile phones. This card weighs about 0.8 grams and measures 21.5x20x1.4 mm. This was a common size available until even smaller size SD card took over.

Micro SD cards are the smallest of all weighing about 0.25 grams and measuring 15x11x1 mm. These cards are widely used in smartphone, mobile phones and even in tablets.

Micro SD cards can be used in the devices that support Mini and standard SD cards with the help of an adapter. However, standard SD cards will not fit in Mini or Micro SD card slots. So check what type of card your device requires before selecting an SD card.

Speed Class

Just like size, the speed of an SD card also differs. And speed does matter for some tasks. Like if you are shooting RAW images and need to transfer them in one go, then buying a card with more speed makes sense. Else, you need a memory card recovery tool if something goes wrong while transferring.

A high-speed SD card is also important when you are recording high-resolution videos and saving them straight to your SD card. If your objective is only to store media files from smartphone or laptop then, speed isn’t really that important.

The term “Speed Class” is used to measure the speed of an SD card. However, the SD Association don’t exactly define the speed of a standard SD card, but they just provide the guidelines. Now, let's look at the different types of speed class.

There are 4 types of speed classes available – 10, 6, 4 and 2.

10 being the fastest and 2 the slowest. For a standard definition video recording, class 2 is suitable. Class 4 and 6 can be used for high-definition video recording. For full high-definition video recording, you can use class 10.

What about professional photographers who shoot RAW images or HDR video? Well, for all professional who are into RAW shooting or heavy video recording, you have Ultra High-Speed SD cards – 1 and 3. These cards can be identified with letter ‘U’ on them. Whereas class 2 to 10 have ‘C’ alphabet.

Also Read: How to recover deleted photos from sd card


Again, the capacity of the SD card differs too. This where the markings SD, SDHC or SDXC comes in. The standard SD cards come with less than 2 GB or sometimes 4 GB storage capacity.

The cards available these days have SDHC marking on them. These cards are used in smartphones and other devices which support high storage capacity. The SDHC or “High Capacity” cards are basically made for day-to-day usage. The cards come in 2 GB to 32 GB in size.

Next, comes the SDXC. These are usually paired with U1, U3 and class 10. XC which stands for “eXtended Capacity” are created for high performance and have 32 GB to 2 TB storage capacity. Which also means they are expensive!


When buying an SD card make sure to check your device user manual on what size, speed, and capacity it supports. So that you’ll buy the right SD card. At the same time, it’s also good to buy the future ready card than the present device as the technology is moving fast forward. You never know when you might upgrade your device.

Things to Look for Before Buying an SD Card was last modified: September 10th, 2019 by John Harris

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