MicroSD U1 vs. U3: What’s the Difference and Which is Better?

MicroSD U1 vs. U3: What’s the Difference and Which is Better?

Posted on Oct 04, 22 by Christian Muniz

How to Choose an SD Card: Class and Speed Ratings Explained

You might find yourself needing an SD card if you just purchased a new Nintendo Switch, GoPro camera, Android tablet or even a new camera. In order to avoid gear malfunctions or worse, data loss, it's imperative to purchase the right SD card for the job at hand.

Below are a list of reasons explaining the differences between U1 and U3 rated microSDs.

Data Transfer Speed

The first thing to consider between a U1 vs U3 MicroSD is the data transfer speed. Compared to the U1 Micro SD card, the U3 SD card has a faster data transfer speed. If you want to have a high write and transfer speed to record 4K Ultra-HD video, then the U3 SD card is the ideal choice.


When purchasing a new Micro SD card for your device, the storage capacity is also an important factor to consider. The U3 SD card has more capacities available compared to other types of cards like the U1 model, ranging from 32GB as far as to 1TB. This means the U3 specification is more suitable for individuals who want to store higher quality and larger videos - perfect for videographers.

UHS Bus Speed

The UHS Bus speed is usually found on the front of the SD card. The roman number on the SD card ranges from 1 to 3. For example, you will see the
I logo on the Hyundai SD card. The UHS Bus refers to how the data is transferred between the card pins and the host device connector.

Both U1 and U3 SD cards have a single row of pins on the back of the card, the data transfer speed can reach about 100MB/s respectively. Since the U3 model adds the second row of pins, it often has a faster transfer speed than the U1 model.

Although UHS Bus is compatible with a variety of cameras, it’s always better to confirm if it can work with your existing hardware. If you want to upgrade your card, make sure that the camera has a provision to install different UHS formats.

Video Speed Class

Video speed class is another important feature. Usually, you will see a V plus roman number icon on the face of the SD card. If you’ve seen the cards, you know the U1 Micro SD cards don’t have this feature on them. So it’s hard to know the exact video speed class of this card. However, the U3 SD card has the V icon with the number 30 alongside it.

The V30 icon indicates that you can record an HD video at 30mbps without dropping any frames. This function is currently available on SDXC cards only. U3 Micro SD cards provide more video recording options than U1 Micro SD cards.

UHS Speed Class

While UHS speed class is very similar to UHS Bus speed, it plays a different role in Micro SD cards. You also can find the Ultra-High-Speed rating on the face of the SD card. The number inside the U-shaped icon tells you the UHS speed class, which indicates the SD card’s write speed. The number inside of the U-shaped logo of the U1 Micro SD card is 1, while the U3 SD card is 3. That means the U3 SD card has a faster write speed than U1.

U3 Hyundai SD cards transfer data faster than U1 Micro SD cards. If you want to have a high write and copy speed to record 4K UHD video, then Micro SD card U3 is the ideal choice.

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