I have a doubt about USB type declared by smartphone manufacturer. Some smartphone declares USB Type C 3.2, for example Galaxy S20 Ultra.

The new Xiaomi Mi 10 Pro is declared as USB 2.0 on Type C.

I try to check the real connection, and when I connect to my Mac the Samsung I have 480 Mb/s negotiation. Looks like even if Samsung declare USB Type C 3.2 the max data transfer is 480 Mb/s, and I can prove it with a benchmark.

I connect the Xiaomi, the same. The Huawei P30 Pro, the same. Is not the cable: I use a very good cable and when I connect my Oculus Quest to the same port, the connection is negotiated at 5 Gb/s.

So my question: why a lot of smartphone manufacturer declare USB 3.2 port but the data transfer is capped to 480 Mb/s?

  • Does your benchmark measures the USB Transferspeed only? Usually you transfer files via USB and therefore you are measuring the flash performance as well.
    – Robert
    Apr 7, 2020 at 10:38

1 Answer 1


tl:dr; You aren't doing an apple to apple, real-world comparison and missing out on many other factors

You are looking at speeds at the USB controller end on PC, further, it is shared between the ports attached to it drawing incorrect conclusions (because you aren't considering other factors)

  • Firstly, USB 2.0 is half - duplex, which means that while the maximum speed is 480 megabits per second, the actual is roughly half of that. In practice you won't exceed 240 megabits per second speed

In contrast USB 3.0 is full - duplex so, in theory, you can get 10 times higher performance. In practice you aren't likely to get that because of

enter image description here

  • On the far right of the graph, the Galaxy S10e and Honor View 20 provide results indicative of what one can expect from a USB 3.0 and UFS 2.1 hardware combination

  • To the left of those results, the Huawei Mate 30 Pro and OnePlus 7T Pro indicate peak performance from a USB 3.1 and UFS 3.0 memory setup.

Note that the second set of phones have better standards but poorer performance compared to the first! In other words, latest is not equal to best

To sum it up, consider all factors before comparing and do a real world comparison as explained in link above.

  • I try also a live benchmark using a USB 3.0 memory stick. It's the same: the S20 Ultra is very slow. I try also file transfer with a very good USB-C cable, then one I use for the Oculus Quest. Also the P40 Pro is very slow. I cannot obtain the USB 3.0 speed. Apr 7, 2020 at 12:05
  • Does your benchmark use read and write cycles? Is it complete as described in answer? Did you see the test procedure in the last link of the answer? Also edit your question to link the test results very slow is subjective
    – beeshyams
    Apr 7, 2020 at 12:08
  • I'm downloading a 10 GB sample file. Apr 7, 2020 at 12:20

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