Types of SD Cards & their Classes Explained in Detail

Last Updated on September 7, 2022 by Tech Queries Team

SD Card (also known as Memory Card) is often used in our daily lives. We use SD Cards for our Mobile Phones, Digital Camera, Drones, etc. SD Cards are similar to the Flash Drive and are used as External Storage Devices.

But, when you try to purchase an SD Card, you will come across different types of SD Cards. I am not talking about the storage capacity, there are different classes of SD Cards. Therefore, the price also differs.

So, to help you choose the Best SD Card, we will explain What is an SD Card, What are the Types of SD Cards, What are the Classes of SD Cards, and show you How to Choose which one is Best for You.

What is an SD Card?

Our devices like Phones & Cameras have limited Storage. So, if we want to store more data, we have to use a Memory Card (SD Card). SD Card is mandatory for some Devices like MP3 Players and Drones as they don’t have internal storage.

SD Card Stands for Secure Digital Card, and it was first invented in 1999.

You can store any kind of data on an SD Card, like audio, video, images, documents, etc.

Different Types of SD Cards:

SD Cards can be classified by Size, Technology, Capacity, and Class (speed). 

Types of SD Cards (By Size):

Memory Cards come in 3 sizes.

• Full-Size SD Card
• Micro SD Card
• Mini SD Card

Full-Size SD Card:

Full-Size SD Cards are usually used in Laptops, Digital Cameras, DSLR Cameras, etc. They are large in size.

Mini SD Card:

Mini SD Cards were previously used in Mobile Phones. But they got replaced by the Micro SD Cards. They are rarely used now.

Micro SD Cards:

These are the Memory Cards we use in our Mobile Phones and some other smaller devices like MP3 Players.

Micro SD Adapter:

These days, people mostly use Micro SD. So, a Micro SD Adapter was invented that lets you insert Micro SD into Laptops and Digital Cameras. Look at the image below. You need to insert the Micro SD Card into the Adapter, and it works as a Full-Size SD Card.

SD Card Categories (Based on Technology):

Based on Technology, we can categorize SD Cards into three Types.

• (Basic) SD
• SD HC
• SD XC
• SD UC

SD (Secure Digital):

The technology used to manufacture these cards supported a storage capacity of only 2 GB. 2 GB storage was more than enough for Smartphones a decade ago. 

However, in this era, we use HD, UHD, and 4K media. So, 2 GB wasn’t enough. Moreover, the SD Card would support only FAT 12 and FAT 16 File Systems.

Check out the Difference Between FAT Vs NTFS Vs exFAT and other File Systems.

SD HC (SD – High Capacity):

Therefore, a New Technology was introduced called SD HC. This technology allowed us to manufacture SD Cards upto 32 GB. They use the FAT32 File System.

SD XC (SD – Extreme Capacity):

As we are moving towards 4K and 8K resolution, even 32 GB won’t be enough. Hence, an even more advanced Technology was introduced that increased the storage capacity of SD Cards from 32 GB to 2 TB.

SD UC (SD – Ultra Capacity):

It is the future-proof SD Card technology that will have a storage capacity of 128 TB. Moreover, you will get transfer speeds of nearly 1 GB/s.

The XC and UC SD Cards use the exFAT File System.

Types of SD Cards (Based on Storage Capacity):

Previously, we used to have SD Cards with a capacity of 64MB, 128 MB, 256 MB, 512 MB, and 1 GB. But, as we moved towards the future, we got 2 GB, 4 GB, 8 GB, 16 GB, and 32 GB SD Cards. Nowadays, you will also find SD Cards with a storage capacity of 64 GB, 128 GB, 256 GB, 512 GB, and even 1 TB. 

What are the Classes of SD Cards?

We can also classify the Types of SD Cards based on their Class. The Class is indicated with a number in a circle. The class basically indicated the speed of the SD Card.

Classes of SD Cards:

• Class 2
• Class 4
• Class 6
• Class 10
• Class 10- UHS 1
• Class 10- UHS 2
• Class 10- UHS 3
• Express

If a card has a Class 2 logo, it means that the card can support a minimum write speed of upto 2 MB per Sec. 

Similarly, Class 10 SD Cards can have a minimum write speed of 10 MBps. However, Class 10 has three more advanced versions indicated as U1, U2, and U3. 

The UHS 1 (Ultra High Speed) standard SD Cards can have a transfer speed of 50 MBps to 180 MBps.

The UHS 2 SD Cards can offer a speed of 156 MBps to 321 MBps.

And, the UHS 3 SD Cards can have a transfer speed of 312 to 624 MB/s

There is also the latest technology called SD Express or EX Express that can have a transfer speed of 950 MB/sec to 400 MB/sec

More Classes (A, V, X):

If you purchase the latest SD Card model, you will see two more specs on the Card that are indicated by the letters A and V.

Application Performance Class (A):

The Application Performance Class Standard was introduced for SD Cards specially used for Mobile Phones. 

So, if you are installing or moving Apps and Games to the SD Card, you will get faster loading and better app performance if the SD Card has A1 and A2 Standards.

A1 has a minimum write speed of 400 IOPS, and a read speed of 1500 IOPS. Whereas the A2 has a minimum write and read speed of 2000 IOPS and 4000 IOPS respectively.

Video Speed Class (V):

They are usually indicated as V6, V10, V30, V60, and V90.

V6 SD Cards indicate Class 6, which has a maximum bitrate of 45 Mb/sec. 

V10 indicates the Class 10 UHS 1 with a max speed of 75 Mb/sec.

V30, V60, and V90 indicate the Class 10 UHS 3 with a max bitrate of 220 Mbps, 460 Mbps, and 700 Mbps respectively.

Check out the difference between MBps and Mbps.

What are the Numbers with X?

You will also see another specification like 633x, 1800x, etc. on the SD Card. This is actually a marketing stunt. It indicates that the Speed of the SD Card is 633 times more compared to the first memory card. Basically, it doesn’t matter much as we can determine the speed using the Class. 

Top SD Card Manufacturers:

Here are some of the leading and trusted SD Card Manufacturers.

• SanDisk
• Samsung
• HP
• Lexar
• Transcend
• Kingston
• PNY
• Gigastone

The first SD Card was made by the combined efforts of SanDisk, Toshiba, and Panasonic. 

How to Choose Which Card is Better for you?

1. First, you should see what Types of SD Card are supported by your Device. You can identify by using the device specs or by looking at the SD Card slot size. As Mini SD Cards are not used thesedays, it will be either a Full-size SD Card or a Micro SD Card.

2. Decide how much storage you want. It varies from person to person. If you like to store music and images on your phone, then 4-8 GB cards will be enough. However, if you shoot 1080p or 4K videos, then you must have at least 16 GB of storage. If you ask me, I would choose a 32 or 64 GB SD Card based on my activities. 

Based on the Storage Size, we get the suitable technology. Note that the Technology is not reverse compatible. Therefore, check the device specs to see which type of SD Card is compatible with it.

3. Third step is to choose the Class. Generally, a Class 4 or Class 6 is suitable for every user of the present generation. However, if you are recording in HD and chose an SD card as the storage, then I suggest getting a Class 10 SD Card. If your budget allows, you can even go for Class UHS1 or Class UHS3. For 4K recording, you must choose UHS 1 or UHS 3. Moreover, if you are moving applications and games to the SD Card, then you should choose a Class 10 Card. Because, the apps and games will load slower on Class 2, 4, and 6 cards.

4. Finally, choose the brand. As we have mentioned, there are several brands that manufacture SD Cards. However, we always purchase from a trusted and reputed manufacturer.

Note: You should also consider your budget before buying an SD Card. The Price of the SD Cards will increase with increasing speed and capacity. Moreover, some brands offer it less price and some have a comparatively high price. 

My suggestion is, that it does not matter how much capacity or whichever class you use. Do not compromise while choosing the Brand. Popular brands are trusted manufacturers. Unpopular brands may offer you the SD Card for a lower price. But, the chances of losing your data due to corruption will be more.

Frequently Asked Questions:

Conclusion:

Now that you understand What is an SD Card and What are the Types of SD Cards, you will be able to choose the Best SD Card that is suitable for you. Follow our guide on How to Choose the Best SD Card as well. We store our important data in our SD Cards. So, always choose the Best Quality SD Card even if it costs a little more.