With so many types, standards, and speed classes of SD cards, you may find it hard to decide which SD card you actually need for recording videos. So in this article, I’ll explain you all about the various standards of SD card speed and classes. You’ll also get a quick recommendation of a few fast SD cards that are good for general video recording videos (up to 4k) with most cameras and GoPros.

 

Speed Class Standards


Recording videos requires a constant minimum write speed to avoid ‘frame drop’ while you’re recording. A “fast” SD card would ensure a smooth video recording as well as proper playback. The SD Association has defined various Speed Class standards. This is mainly useful for camcorders, video recorders and other devices with video recording capabilities.

There are three kinds of SD Card speed indications:

  1. Speed Class
  2. UHS Speed Class
  3. Video Speed Class

These speed classes are labelled on the front side of each SD memory card. The labelling is in the form of little numbers with a circle, a U shape, or a V shape. The manufacturers use these “classes” to determine the speed of the memory card.

#1. Speed Class

The Speed Classes include: Class 2, 4, 6 and 10. Class 2 cards are the slowest and class 10 cards are the fastest. The class number refers to the minimum write speeds in megabytes per second (MB/s), so Class 2 = 2MB/s, Class 4 = 4MB/s, Class 6 = 6MB/s, and Class 10 = 10MB/s.

#2. UHS Speed Class

The UHS Speed Classes are UHS Speed Class 1 (U1) and UHS Speed Class 3 (U3). On the top high-end cards, the speed class rating is designated with a U symbol. U1 supports at least a 10MB/s write speed (like a Class 10), and U3 cards offer at least a 30MB/s write speed. If you shoot in 4K, you need a minimum U3 SD card.

UHS Speed Class has another classification as well. It includes UHS-I, UHS-II & UHS-III. This classification refers to the absolute top theoretical speed of the SD card, instead of the minimum speed. It’s a good way to gauge burst shot speeds. UHS-I Cards have a maximum speed of 104 MB/s, while UHS-II cards have a maximum speed of 312 MB/s. The newer UHS-III Cards theoretically support up to 624 MB/s, but aren’t widely available yet.

#3. Video Speed Class

The Video Speed Classes include V6, V10, V30, V60 and V90. For 4K, a video speed class of V30 or more is ideal.

Have a look at the graphic below to understand the minimum sequential write speed you’ll get with each SD Card speed class. It also has the recommended corresponding video format for different speed classes.

video speed class

Graphic Source: SD Association

From this graphic, it’s clear that if you’re looking to record standard definition videos, SD cards with specifications Class 10, U1 & V10 are sufficient. For HD/Full HD video recording, you need up to U3, V30 rating. For 4K videos, you need an SD card with video speed class V30 and above. Lastly, for 8K video recording, you need at least a V60 video speed class rating.

 

Recommended SD Cards for 4K Video Recording


It’s generally a good idea to get a high-speed SD card, especially if you are shooting in RAW or filming high-resolution videos. An SD card that offers a minimum of 30MB/sec write speed is sufficient for recording in 4K. So, for 4K, a video speed class of U3, V30 or more is ideal.

Here are the top three recommended SD Cards for smooth and hassle-free 4K Video Recording:

#1. SanDisk Extreme UHS-I SD Card

  • Brand: SanDisk
  • Speed Class: UHS-I, U3, V30
  • Maximum Read Speed: 160MB/s
  • Maximum Write Speed: 90MB/s
  • Storage Capacity: 32GB, 64GB, 128GB, 256GB, 400GB, 512GB, 1TB
SanDisk 256GB Extreme MicroSDXC...
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SanDisk 256GB Extreme MicroSDXC...
  • Up to 160MB/s read speeds to save time transferring high res images and 4K UHD...
  • Up to 90MB/s write speeds for fast shooting; Requires compatible devices capable of...
  • 4K UHD and Full HD Ready with UHS speed class 3 (U3) and video speed class 30 (V30)

The SanDisk Extreme UHS-I SD Card is arguably the most popular SD card and our top recommendation for recording 4K videos. With its awesome write speeds of up to 90 MB/s and read speeds of up to 160 MB/s, you can easily capture Full HD, 4K videos, as well as raw and burst photography with your camera.

Available in 32GB, 64GB, 128GB, 256GB, 400GB, 512GB and 1TB sizes, the SanDisk Extreme SD Card is ideal for recording extreme sports and other fast-action activities.

#2. SanDisk Extreme PRO UHS-I SD Card

  • Brand: SanDisk
  • Speed Class: UHS-I, U3, V30
  • Maximum Read Speed: 170MB/s
  • Maximum Write Speed: 90MB/s
  • Storage Capacity: 32GB, 64GB, 128GB, 256GB, 512GB, 1TB
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SanDisk 128GB Extreme PRO SDXC...
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SanDisk 128GB Extreme PRO SDXC...
  • Shot speeds up to 90MB/s, transfer speeds up to 170MB/s [requires a compatible device...
  • Perfect for shooting 4K UHD video (1) and sequential burst mode photography, (1)Full...
  • Capture uninterrupted video with UHS Speed Class 3 (U3) and video Speed Class 30...

With top notch read (up to 170 MB/s) and write speeds (up to 90MB/s), the SanDisk Extreme PRO is one of the fastest UHS-I microSD cards. With these speeds, you can smoothly capture burst photos, 4K videos and access many other features of your camera without any hassle.

SanDisk Extreme PRO UHS-I SD Card comes in 16GB, 32GB, 64GB, 128GB, 256GB, 512GB and 1 TB variants. It’s built for and tested in harsh conditions, which is why it’s temperature-proof, waterproof, shock-proof, and X Ray-proof.

#3. Lexar Professional UHS-II U3 1000x SD Card

  • Brand: Lexar
  • Speed Class: UHS-II, U3, V60
  • Maximum Read Speed: 150MB/s
  • Maximum Write Speed: 90MB/s
  • Storage Capacity: 32GB, 64GB, 128GB, 256GB
Lexar Professional 1000x 128GB...
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  • High-speed performance—leverages UHS-II technology (U3) for a read transfer speed...
  • Premium memory solution for sports camcorders, tablets, and smartphones
  • Designed for high-speed capture of high-quality images and extended lengths of 1080p...

Designed for DSLRs, action cameras and drones, the Lexar Professional 1000x leverages UHS-II technology (U3) for an optimum read transfer speed. It’s capable of providing amazing read speeds of up to 150 MB/s and write speeds of around 90 MB/s, making it perfect for high-speed capture of high-quality images and extended lengths of 1080p Full-HD and 4K video.

Lexar Professional UHS-II U3 1000x SD Card backwards compatible and works at the highest UHS-I speeds if your camera supports only UHS-I SD cards.  It comes in multiple sized variants: 32GB, 64GB, 128GB and 256GB.

 

What SD Card Speed do You Need for Video Recording?


After reading this article, you must have an idea of how important the SD card speed is for video recording. If you don’t have a fast memory card in your camera, it may adversely impact your camera’s performance and videos files may fail to save. The SD card speed you need for video recording depends mainly upon the bitrate of the video.

Generally, the higher the resolution and frame rates, the higher the bitrate. So, as a general rule of thumb, if you’re shooting at high resolutions (eg. 4K) or high frame rates (eg. 240fps) go for a minimum of U3, V30 card.

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