USB Standards: A Plain-English Guide
USB naming is needlessly confusing. Here is what USB 2.0, USB 3.0, USB 3.2, USB4, USB-A and USB-C actually mean – and which matters when buying a dongle.
USB connectors vs USB standards
The first thing to understand is that the connector shape and the speed standard are separate things. USB-A (the rectangular plug) and USB-C (the oval plug) are connector types. USB 2.0, USB 3.0, and USB4 are speed standards. A USB-C port can be USB 2.0, USB 3.2, or USB4 speed – you cannot tell from the connector alone.
USB speed standards
| Standard | Max Speed | Common Name |
|---|---|---|
| USB 2.0 | 480 Mbps | Hi-Speed USB |
| USB 3.2 Gen 1 | 5 Gbps | USB 3.0 / USB 3.1 Gen 1 |
| USB 3.2 Gen 2 | 10 Gbps | USB 3.1 Gen 2 |
| USB 3.2 Gen 2×2 | 20 Gbps | USB 3.2 |
| USB4 Gen 2 | 20 Gbps | USB4 |
| USB4 Gen 3 | 40 Gbps | USB4 40Gbps |
What this means for dongles
For most dongles, USB 2.0 is adequate. A WiFi dongle transferring data at 500 Mbps theoretical maximum does not saturate USB 2.0’s 480 Mbps bandwidth in real-world conditions. A 5G dongle reaching 400 Mbps downloads benefits from USB 3.0.
The practical rule: if a dongle spec sheet mentions USB 3.0, use it in a USB 3.0 port (blue inside on USB-A) to get the stated performance. Using a USB 3.0 dongle in a USB 2.0 port limits it to USB 2.0 speeds.
USB-C vs USB-A dongles
Older computers have USB-A ports. Modern thin laptops and smartphones typically have USB-C only. If you have a laptop with only USB-C ports and you want a dongle, you need a USB-C dongle or a USB-C hub to give you USB-A ports. Many dongles now come with both a USB-A and USB-C connector on a short cable.