If you are looking for a new SD card, you might be confused by the SD card speed classes.

These ratings indicate the minimum write speed of the SD card, which is crucial for determining how quickly data can be saved to the card.

In this post, you’ll learn about the differences between SD card speed classes and how to choose the right one for your needs.

 

 Different SD Card Speed Classes


When it comes to SD cards, speed matters! The speed class rating of an SD card refers to its minimum write speed or the speed at which it can write data to the card. The higher the speed class, the faster the card can write data. Does it all sound quite confusing? Then I recommend you to read How SD Cards Work

There are three different speed class ratings that you may encounter: Speed Class, UHS Speed Class, and Video Speed Class. Each of these ratings indicates the minimum write speed of an SD card and can help you choose the right card for your needs.

Speed Class

The original speed class rating system was introduced in 2005 and is denoted by a number inside a “C” symbol (e.g. C2, C4, C10). This rating indicates the minimum sustained write speed of an SD card, measured in megabytes per second (MB/s). For example, a Class 10 SD card has a minimum sustained write speed of 10 MB/s.

Here’s what to expect from different speed classes:

  1. Class 2: This is the slowest SD card speed class, with a minimum write speed of 2 MB/s. Class 2 cards are suitable for basic tasks like storing music or photos, but they may struggle with video or high-resolution images.
  2. Class 4: Class 4 SD cards have a minimum write speed of 4 MB/s. These cards are a step up from Class 2, and can handle basic video recording as well as larger image files.
  3. Class 6: With a minimum write speed of 6 MB/s, Class 6 SD cards are a good choice for capturing HD video or shooting high-resolution photos.
  4. Class 10: This is the most common SD card speed class, with a minimum write speed of 10 MB/s. Class 10 cards can handle full HD video recording and are suitable for high-speed continuous shooting with DSLR cameras.

When choosing an SD card, it’s important to consider what you’ll be using it for. If you just need to store a few photos or music files, Class 2 or 4 cards may be sufficient. However, if you’re planning to shoot video or capture high-resolution images, it’s worth investing in a higher-speed class card like a Class 10.

UHS Speed Class

The UHS (Ultra High Speed) Speed Class rating system was introduced in 2009 and is denoted by a number inside a “U” symbol (e.g. U1, U3). UHS Speed Class ratings indicate both a minimum sustained write speed and a minimum sequential write speed, measured in megabytes per second. For example, a U3 SD card has a minimum sustained write speed of 30 MB/s and a minimum sequential write speed of 30 MB/s.

In addition to the UHS Speed Class rating system, there are also different versions of UHS technology that offer even higher transfer speeds. These include UHS-I, UHS-II, and UHS-III, and they are denoted by different logos on the SD card.

Here’s what to expect from different UHS speed classes:

  1. U1: UHS (Ultra High Speed) Speed Class 1 SD cards have a minimum write speed of 10 MB/s, but they can also support faster write speeds up to 104 MB/s. These cards are ideal for capturing high-speed action shots and 4K video.
  2. U3: UHS Speed Class 3 SD cards have a minimum write speed of 30 MB/s, and can support faster write speeds of up to 312 MB/s. These cards are recommended for professional photographers and videographers who need to capture high-quality images and videos at high frame rates.
  3. UHS-I: UHS-I SD cards are the most common and offer a maximum bus speed of 104 MB/s. They are compatible with most devices that have an SD card slot and support UHS technology.
  4. UHS-II: UHS-II SD cards are designed for devices that require even higher transfer speeds, such as professional cameras and video recorders. They offer a maximum bus speed of 312 MB/s, but are only compatible with devices that support UHS-II technology and have a UHS-II-compatible card slot.
  5. UHS-III: UHS-III SD cards are the latest and fastest type of SD card available, offering a maximum bus speed of 624 MB/s. However, they are still relatively new and are only compatible with devices that support UHS-III technology and have a UHS-III-compatible card slot.

It’s worth noting that while the speed class rating indicates the minimum write speed of an SD card, the actual write speed may be higher than the rating, depending on factors like the device it’s being used in and the type of data being written. Additionally, not all devices may support higher speed class ratings, so it’s important to check your device’s specifications before purchasing an SD card. If you’re a professional photographer or videographer, a UHS Speed Class 3 (U3) card is the way to go.

If you have a GoPro and wonder what UHS speed class, size and capacity SD Card you should choose check out this article.

Video Speed Class

The Video Speed Class rating system was introduced in 2016 and is denoted by a “V” followed by a number (e.g. V30, V60, V90). Video Speed Class ratings are specifically designed for recording video and indicate the minimum sustained write speed of an SD card when recording video at various resolutions and bitrates. For example, a V30 SD card has a minimum sustained write speed of 30 MB/s and can handle recording 4K video at up to 60 frames per second.

Here’s what to expect from different video UHS speed classes:

  1. V6: This video speed class has a minimum sustained write speed of 6 MB/s and is suitable for recording standard definition (SD) video.
  2. V10: With a minimum sustained write speed of 10 MB/s, this video speed class can handle recording HD video up to 720p.
  3. V30: V30 SD cards have a minimum sustained write speed of 30 MB/s, making them suitable for recording HD video up to 1080p and 4K video.
  4. V60: This video speed class has a minimum sustained write speed of 60 MB/s and can handle recording 4K video at higher bitrates.
  5. V90: The highest video speed class, V90 SD cards have a minimum sustained write speed of 90 MB/s and are recommended for recording high-quality 4K and 8K video.

It’s worth noting that not all devices may support the higher video speed classes, so it’s important to check your device’s specifications before purchasing an SD card. Additionally, using a card with a lower speed class than what is recommended for video recording may result in dropped frames, buffering, or other issues during playback.

Have a look at the graphic below to understand more about different SD card speed classes:

speed class table

 

Best SD Cards in Different Speed Class Combinations


When choosing an SD card, be sure to consider factors like read and write speeds, storage capacity, and compatibility with your device. These factors will also affect its price. If you wonder how much are SD cards visit this article.

Here are some of the best SD cards that feature different speed class combinations:

Best UHS-I, U3, V30, Class 10 SD Card

SanDisk Extreme PRO UHS-I

SPECIAL SALE
SanDisk 128GB Extreme PRO SDXC UHS-I Memory Card - C10, U3, V30, 4K UHD, SD Card - SDSDXXD-128G-GN4IN
  • Save time with card offload speeds of up to 200MB/s powered by SanDisk QuickFlow...
  • Pair with the SanDisk Professional PRO-READER SD and microSD to achieve maximum...
  • Shot speeds up to 90MB/s (Write speed up to 90MB/s. Based on internal testing;...

This SD card is a popular choice among photographers and videographers who need fast and reliable performance. It offers read speeds of up to 200 MB/s and write speeds of up to 104 MB/s, making it great for high-resolution photos and 4K video.

sd card speed classes

Best UHS-II, U3, V90, Class 10 SD Card

SanDisk Extreme PRO UHS-II

SPECIAL SALE
SanDisk 128GB Extreme PRO SDXC UHS-II Memory Card - C10, U3, V90, 8K, 4K, Full HD Video, SD Card - SDSDXDK-128G-GN4IN
  • Tap into pro performance designed for professional and advanced photographers and...
  • Super-fast write speeds of up to 260MB/s help rapidly clear buffer time to support...
  • Sustained V90 video speeds and UHS Speed Class 3 (U3) deliver cinema-quality 8K, 4K...

This SD card is a popular choice among professionals who need fast and reliable performance. It offers read speeds of up to 300 MB/s and write speeds of up to 260 MB/s, making it great for high-resolution photos and 4K, 5K, or even 8K videos. It also comes with a lifetime limited warranty.

Best UHS-II, U3, V60, Class 10 SD Card

Sony TOUGH-M series UHS-II

SPECIAL SALE
Sony TOUGH-M series SDXC UHS-II Card 128GB, V60, CL10, U3, Max R277MB/S, W150MB/S (SF-M128T/T1)
2,344 Reviews
Sony TOUGH-M series SDXC UHS-II Card 128GB, V60, CL10, U3, Max R277MB/S, W150MB/S (SF-M128T/T1)
  • Waterproof (IPX8)/ Dustproof (ipx6)3
  • Up to 277MB/s read speed and 150MB/s write speed
  • Toughness design (18x stronger than standard UHS II card)

This SD card is designed for professional photographers and videographers who need fast and reliable performance. It offers read speeds of up to 277 MB/s and write speeds of up to 150 MB/s, making it great for high-resolution photos and 4K video. It’s also durable and resistant to shock, vibration, and extreme temperatures.

 

Last Word Of Advice


If you’re looking for an SD card for everyday use, a Class 10 card is a great choice.

For professional photographers and videographers who need faster speeds, UHS-II cards offer even greater performance. However, UHS-III cards are not widely available due to the limited number of devices that support the UHS-III standard.

 

If you don’t know either opt for SD or SSD read: SD Card vs SSD Drive

 

 

Thanks for reading!

I hope this guide helped you learn about the different SD card speed classes and how they impact device performance.

 

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