in Software

USBO-LOGOS-2There are various method and utilities to test how fast are your external (and internal) drives really working. You might have bought a USB 3 thumb drive (or a certain USB port) that doesn’t appear to be as fast as others and this will help you verify your suspicions.

First up, what are you supposed to be getting as a result? Well, these vary a lot more than what you might expect. Below are the theoretical speeds for USB 2.0, 3.0 and 3.1:USB-LOGOS-1

These theoretical read rates translate into:

  • USB 2.0 – 480 megabits / s – 60 megabytes / second
  • USB 3.0 – 4.8 gigabits / s – 600 megabytes / second (10x USB 2.0)
  • USB 3.1 – 10 gigabits / s – 1.250 megabytes / second ( 2x USB 3.0)




Most of us do not have USB 3.1 computers just yet, but it should be a very good  improvement, though not as dramatically significant as the speed increase from USB 2 to USB 3.

So here’s the free tool for the job, the Blackmagic Disk Speed Test (get it here from Apple’s Mac AppStore). This app if offered by Blackmagic Design, the makers of impressively powerful Video gear, including the Blackmagic Digital Film cameras 

Just download the app and open it. You’ll see immediately it’s made for Video editing in mind, with an easy to read table of video formats and resolutions/fps available in the bottom half:


First hit the Settings icon in the center, above the Start button and select the drive you want to test.


After that just hit Start and let it run for how long you want to, stopping by pressing Start again.



I tested these three USB devices:

  • Seagate Expansion 1Tb Portable Drive (USB 3.0) – SDR00F1 STBX1000101
  • Sandisk Cruzer Fit USB 16Gb Flash Drive (USB 2.0)
  • Transcend 1TB StoreJet 25M3 Anti-Shock External Hard Drive (USB 3.0) – TS1TSJ25M3

Test 1 – Left USB port – Seagate

Note that this hard-drive was already connected to my MacBook Pro Retina for a few hours now and I had been working on files inside.

Seagate benchmark

Seagate – First test – MBPr Left port

  • Write: 36.0 MB/s
  • Read: 37.9 MB/s

Pretty slow speeds here, well under the theoretical 600 MB/s!


Test 2 – Right USB port – Sandisk 16Gb

Sandisk 16Gb USB - First test - MBPr Left port

Sandisk 16Gb USB – First test – MBPr Left port

  • Write: 4.2 MB/s
  • Read: 18.1 MB/s

Again, well under, but 18 MB/s is much closer to 30 MB/s.


Test 3 – Right USB port – Transcend 1Tb

Test 3 - Right USB port - Transcend 1Tb

Test 3 – Right USB port – Transcend 1Tb

  • Write: 77.4 MB/s
  • Read: 95.3 MB/s

Well under 600 MB/s, but better than Test 1.


Test 4 – Right USB port – Seagate 1Tb

Let’s see if switching ports makes any difference…

Test 4 - Right USB port - Seagate 1Tb

Test 4 – Right USB port – Seagate 1Tb

  • Write: 85.8 MB/s
  • Read: 89.4 MB/s

And it does! So the culprit was the operating system, not the drive.

Test 5 – Left USB port – Transcend 1Tb

Test 5 - Left USB port - Transcend 1Tb

Test 5 – Left USB port – Transcend 1Tb

  • Write: 72.3 MB/s
  • Read: 102.4 MB/s

So we got similar speeds to the first test.


It’s difficult to take any conclusions out this, but one thing is for sure: theoretical speeds are not easy to get in any situation. These aren’t high performance devices but they all performed well under the theoretical read speeds. In any case Blackmagic Disk Speed Test is a very handy tool to have an idea of how well your devices perform in real life scenarios, though it would be nice to have some graphical speed charts and averages.