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The upcoming USB 3.2 standard will provide a maximum speed of 20 Gbps when products supporting it hit the market later this year, but due to confusing labeling from USB-IF, the USB industry group, it may be difficult to figure out what speed any particular device supports. That’s because USB-IF is retroactively subsuming the older USB 3.0 and USB 3.1 standards under the new USB 3.2 name. Here’s how the new names work out:
|Spec||Speed||New Spec Name||Marketing Name|
|USB 3.0||5 Gbps||USB 3.2 Gen 1||SuperSpeed USB|
|USB 3.1||10 Gbps||USB 3.2 Gen 2||SuperSpeed USB 10Gbps|
|USB 3.2||20 Gbps||USB 3.2 Gen 2×2||SuperSpeed USB 20Gbps|
To be fair, USB-IF is being consistently confusing, since the initial release of USB 3.1 was called USB 3.1 Gen 2, and USB-IF also then retroactively renamed USB 3.0 to USB 3.1 Gen 1. What was wrong with the simple USB 3.0, 3.1, and 3.2 names?
The practical upshot of all these naming changes is that any given “USB 3.2” device might not provide the speed you expect, so you’ll have to read the specifications carefully.
Just before we published this article, the USB Promoter Group announced the draft specification of USB4, due in the middle of 2019. USB4 is slated to be backward-compatible with USB 2, USB 3.2, and Thunderbolt 3. In fact, it’s based on Thunderbolt 3 and doubles USB 3.2’s 20 Gbps top throughput to 40 Gbps, enabling it to support multiple simultaneous data and display protocols. What’s not clear is how USB4 will differ from Thunderbolt 3, given its backward compatibility, USB-C connector, and need for new cables certified for 40 Gbps.