USB 2.0 vs USB 3.x: Speeds Explained
What are the official USB speeds?
The USB-IF’s USB 3.2 language guidelines list three rates with recommended consumer names:
| Technical name | Speed | Marketing name |
|---|---|---|
| USB 3.2 Gen 1 | 5 Gb/s | SuperSpeed USB |
| USB 3.2 Gen 2 | 10 Gb/s | SuperSpeed USB 10Gbps |
| USB 3.2 Gen 2x2 | 20 Gb/s | SuperSpeed USB 20Gbps |
The USB 3.2 page adds that 20 Gb/s comes from two lanes of 10 Gb/s, that the specification absorbed all earlier 3.x versions, and that products are backwards compatible and run at the lowest common speed.
How the versions fit together
Wikipedia’s version history gives the timeline of how USB got faster:
| Version | Released | Top signalling rate |
|---|---|---|
| USB 1.1 | September 1998 | 12 Mbit/s |
| USB 2.0 | April 2000 | 480 Mbit/s |
| USB 3.0 | November 2008 | 5 Gbit/s |
| USB 3.1 | July 2013 | 10 Gbit/s |
| USB 3.2 | September 2017 | 20 Gbit/s |
| USB4 | August 2019 | 40 Gbit/s |
| USB4 version 2.0 | October 2022 | 80 Gbit/s |
Wikipedia adds that the two-lane 20 Gbit/s mode of USB 3.2 is only possible with a full-featured USB-C cable, so a phone, a cable and the device at the other end all have to support it.
Why are the USB names so confusing?
USB 3.x has been renamed more than once. Wikipedia explains that “USB 3.2 Gen 1” is the original USB 3.0 at 5 Gbit/s under a newer name, and that more recent marketing names simply state the speed: USB 5Gbps, 10Gbps, 20Gbps, 40Gbps and 80Gbps. If a product page says “USB 3.2”, it is not enough on its own. You need the speed, or the Gen number.
How big is the gap?
Apple lists USB 2 at up to 480 Mb/s for the iPhone 17. Five gigabits is 5,000 Mb/s, roughly ten times that figure. Real transfers are slower than the signalling rate. Wikipedia puts the real-world speed of USB 2.0 at roughly two-thirds of its 53 MB/s theoretical maximum, and USB 3.0 at about 330 MB/s once overhead is counted.
Here is what that means for copying 10 GB of photos and video, using Wikipedia’s figures. These are estimates from those numbers, not lab tests, and a phone’s own storage and the computer can slow things further.
| Link | Approximate real speed | Time for 10 GB |
|---|---|---|
| USB 2.0 | About 35 MB/s | About 5 minutes |
| USB 3.0 (5 Gbit/s) | About 330 MB/s | About 30 seconds |
What does this mean for my phone?
- Check the phone’s own spec. Several phones in our library list USB 2 speed even though the plug is USB-C. Apple’s figure for the iPhone 17 is the example above. Our phone pages show the speed each maker publishes.
- The slowest part wins. If the phone is USB 3 but the cable is USB 2, you get USB 2 speed. A cable can be USB 2 even when the phone is faster, so check the cable’s own rating too.
- Charging does not need speed. A cable that is slow for data can still charge at full wattage if it is rated for it. See the wattage guide.
- Color is only a hint. Blue ports mark SuperSpeed on a computer, but the maker’s stated speed is the reliable guide.
What this means when buying
Your phone, cable and the device on the other end all matter, because the link runs at the slowest part. Read USB-C for the connector, cable buying safety for trusted sources, and the cables hub for the rest.