External drives · Speed, cables and hardware
What do USB 3.0, 3.1, 3.2 and USB4 mean when buying a drive?
Short answer: They're USB generations with confusing, repeatedly changed names. Compare the speed in Gbps on the drive, cable and port instead — the slowest part sets the speed, and some top USB modes aren't supported by Mac ports.
They're generations of the USB standard, and the names have been changed several times, so the same speed can appear under different labels. Ignore the version number and look at the speed in Gbps printed on the drive, cable and port — that's what decides how fast a copy can go.
Rules of thumb for a Mac:
- The connection runs at the speed of the slowest part — drive, cable, hub or port.
- Some very fast USB modes aren't supported by Mac ports, so a drive advertised at the top USB speed may run slower on a Mac.
- USB4 and Thunderbolt drives work at their best on Macs with Thunderbolt or USB4 ports.
For choosing between the two families, see Thunderbolt or USB-C.