Since I got one yesterday Article on Y-USB cables wrote, I had to research how fast USB 2.0 actually is compared to USB 3.0. When it comes to Y cables, there are those that support USB 2.0 and only a few that are compatible with the USB 3 standard. I would also like to clarify here whether and when this is important.

SanDisk SSD hard drive

If you use SSD storage devices like this one from SanDisk (which I use), you should make sure that the cable or the hub with which you connect the storage device to the computer also supports USB 3 (Photo: SanDisk).

When does the difference matter?

To me, USB 2.0 always sounds like an age-old standard that is insanely slow. But if you look at the speeds in comparison, USB 2.0 is not really slow with almost 40 MB per second (usable data rate).

This speed should easily be sufficient for DVD players and CD drives. But if you think of fast SSD memories that can transfer several hundred megabytes per second, you quickly understand why USB 3.0 support is perhaps the better choice after all. A USB 2 hub would mercilessly slow down an SSD and thus bring the entire performance to its knees.

Recommended reading: I already have a more general article on the differences between USB C, USB 3.1 and Thunderbolt 3 written, which might also be interesting in this context.

The USB Type C connection of the 12 inch Apple MacBook has the specification USB 3.1 Gen 1 and manages up to 10 GBit / s (Photo: Sir Apfelot).

The USB Type-C port of the 12 inch Apple MacBook from 2015 has the specification USB 3.1 Gen 1, which was then renamed USB 3.2 Gen 1. In practice, this USB standard achieves up to approx. 300 MB / s (Photo: Sir Apfelot).

USB spec speeds compared

But now finally to the actual content of the article, because after all we want to know how the speeds of the USB standards compare. This is the only way to decide whether a device that is only compatible with a certain standard is really fast enough for your own use.

Theoretical speeds and practical values

The information that can be found in the specifications relates to theoretical values ​​(gross data rate), which of course cannot be achieved in practice. In order to have a better comparison, I am listing the theoretical value and a practical value, which is also referred to as the net data rate.

I have the practical values Wikipedia taken from where you can find this note:

Real achievable net data rates are at least 30 percent, but mostly 45 percent below the gross data rate (real measurements on USB 2.0 systems).

With the data from Wikipedia and some information from other websites, the following table with the net and gross data rates was created.

USB specificationData rate theoryData rate practice
USB 1.01,5 MB / s1,0 MB / s
USB 2.060 MB / s40 MB / s
USB 3.2 Gen 1625 MB / s300 MB / s
USB 3.2 Gen 21.250 MB / s900 MB / s
USB 3.2 Gen 2x22.500 MB / s1.800 MB / s
USB 45.000 MB / sapprox. 2.750 MB / s

Note on the designations:

  • USB 3.2 Gen 1 was formerly also known as USB 3.0 or USB 3.1 Gen 1.
  • USB 3.2 Gen 2 was formerly known as USB 3.1 Gen 2.
The USB-C connection has a few mechanical disadvantages, but it has technical advantages!

The new USB 4 standard uses the well-known USB-C type as the connector type that has been found on Apple Macs for a long time (Photo: Sir Apfelot).

Short trip to USB 4

Incidentally, USB 4 is the successor to USB 3.2 and Thunderbolt 3 and should finally be a standard that is supported equally by PCs and Macs. The first products that support USB 4 cannot be expected until the end of 2020. If you want to find out more about the specifications of USB 4, you will find it here in my post on the subject.

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