What is the difference between micro sd card classes

Consumers can find the best card for a host via Speed Class symbol match; choose the same or higher class symbol card than class symbol of the host indicated. Video Speed Class is also the same. Note that expected write speed will not be available by a combination of different class symbols between host and card such as Host Class 10 and Card U1, Host U1 and Card V10, etc.

By repeating deletion and write of files, data area is gradually fragmented and it influences write speed. Generally, write speed to a fragmented area is slower than sequential write speed due to flash memory characteristics. There are no less than six ways to show how fast a card is, and it's not uncommon for manufacturers to use all of them. The Speed Class shows the minimum write speed of a memory card in megabytes per second.

There are four Speed Classes to choose from:. Showing the base-level performance differences in microSD cards helps the manufacturer communicate whether a card is suitable for your needs. Because this attribute tells you nothing about the SD card's maximum possible speed, it's technically possible for a Class 2 card to be faster than a Class 6 card.

Class 10 cards should always be noticeably faster, though, as they have a bus speed of 25MBps compared to Of course, the devil is in the details. We're listing it as a separate category because some manufacturers list both classes on their cards. The two UHS Speed classes are:. The Application Performance Class specifies a minimum sustained write speed of 10MBps, along with a minimum random read and write speeds measured in input and output operations per second IOPS.

This guarantees an acceptable level of performance when storing and running Android apps on your card. The Application Performance Class is something you can look at when you're planning on installing Android apps on different types of microSD cards. It isn't a necessity, though, as SD cards without the A-rating may still perform adequately.

The Video Speed Class sets a minimum sequential write speed, which is essential when shooting video. The higher the resolution of your video, the faster the speed you need. There are five classes for video:. While it's generally safe to assume that a higher Speed Class correlates to faster all-around performance, and UHS cards faster still, some manufacturers also quote a maximum speed for their products.

These speeds are in megabytes per second and help you pick out the absolute fastest microSD cards. However, the speeds are based on manufacturer tests, so they may represent a best-case scenario rather than real-world performance. In practice, other external factors will affect read and write speeds. The other way manufacturers show the speed of their microSD cards is a throwback to the old CD writing days.

The Class rating is displayed on the card, by a number nested inside a circle. After the Class 10 classification, it becomes a little more complicated. An additional standard called UHS was introduced, which allows cards to reach higher speeds. UHS speed classes are shown on the card with a number inside a U.

Some cheaper action cameras will buffer the recording, but this is not practical in the slower card speed classes, and may cause juddering or stuttering of the recorded footage, as well as other issues. Similarly with the latest Digital SLR Cameras especially in modes such as sport, multi-frame or burst-mode where multiple images are taken, having a faster card will allow you to review the images much sooner less waiting for the images to write to the card.

As a disclaimer, most devices such as cameras, mobile phones and card readers will generally work with older SD Cards , but newer SD Cards with higher Class and Speed classifications may not work in these older devices — check your owners manual or Search online for compatibility for cards that work with your device before purchasing.

Also Full-size SD cards and Micro SD cards may not work in devices that are specifically designed for one or the other, even though smaller cards can fit into larger card slots via adapters see the section below.

The next area of confusion is around speed classes. High-resolution and high bit rate video requires a lot of data to be written to the card very quickly. Stills cameras with high resolutions and fast burst shooting will also take modern cards to their limits. The SD Association devised a way to standardise the speed ratings for different cards. Many SD card manufacturers will also list a specific speed alongside the Class rating. So in this case x 0. On any type of SD card, the Class rating is denoted by a number inside of a C symbol.

This stands for Ultra High Speed and refers to minimum sustained writing performance for recording video. UHS came about due to 4K-capable video devices needing faster write speeds. As a rule of thumb, 4K-capable camcorders will usually require at least a U3 rated SD card.