I have the Late 2013 Macbook Pro, which has two USB 3.0 ports and two Thunderbolt 2 ports. I currently use both USB 3.0 ports and one TB2 port. I want to connect a third USB 3.0 device to the machine, but I don't want to use a USB splitter on one USB port as I'm concerned the devices would draw too much power from the bus. I have no current use for the second TB2 port and I would love to be able to use it for this purpose.

Browsing extensively online, I've found numerous docks, such as Belkin's Thunderbolt Express, that connect via a Thunderbolt cable. This would work, but it's an expensive, 'bulkier' solution (and not the one I'm looking for).

I'm aware that a USB 3.0 device wouldn't be able to take advantage of Thunderbolt's I/O speeds, but it's certainly compatible, which is all I'd need. After all, Apple even sells a Thunderbolt to Firewire Adapter. I also know that Thunderbolt is not only used for digital video purposes (along with the TB > Firewire option, there exists Thunderbolt External Hard Drives).

There are almost no Thunderbolt to USB 3.0 cables/adapters on the market. I'd think this hardware would be more prevalent given the prominence of USB devices out there. What adapters are available for OS X?

  • Apple has released Thunderbolt3/USB-C to Thunderbolt 2/1 adapter for $29. It will require to use USB-C connector from your external devices, but other than that it looks more compatibility-promising than any third-party connectors.
    – yurkennis
    Commented Dec 12, 2016 at 17:27
  • @yurkennis I believe that adapter allows you to connect TB 2 external devices > Mac USB C port, not the other way around...additionally only the newest line of Macs use USB C, so it's still not viable adapter for the 99% of Mac users who remain dependent on USB 3.0 external devices. So, unfortunately still no USB 3.0 > TB 2 adapter from Apple. The third party Kanex adapter is unreliable...Still no good option.
    – njboot
    Commented Dec 13, 2016 at 5:01
  • Quote from the official product page: "As a bidirectional adapter, it can also connect new Thunderbolt 3 devices [=>any USB-C as well] to a Mac with a Thunderbolt or Thunderbolt 2 port."
    – yurkennis
    Commented Dec 13, 2016 at 10:20
  • @yurkennis okay, that makes sense. the male end is USB C and the female TB2, so I guess you'd just flip it by using an additional TB2 cable? at any rate, it's not a USB 3/2 adapter.
    – njboot
    Commented Dec 13, 2016 at 15:17
  • 1
    Not an USB-A female adapter, to be precise.
    – yurkennis
    Commented Dec 13, 2016 at 15:30

6 Answers 6


Thunderbolt and USB are quite different protocols, so you can't just use a cable -- it would need to have active electronics in it to convert between the protocols. And that means it would cost a lot more than a cheap commodity USB hub and so no one would buy it -- they'd just get a hub instead. If you're concerned about the power drain, get a powered USB hub.

  • 1
    As a matter of fact it is not uncommon at all for Apple adapters to contain a whole lot more than basic cables. Prices are also usually dominated by the market.
    – Asmus
    Commented Jun 25, 2014 at 19:08
  • 3
    Thank you for your response. Thunderbolt and Firewire are also very different protocols, as is Thunderbolt/Ethernet. Yet, both adaptors are sold by Apple despite the fact the USB3 connections are much more widely used now than either firewire cables or ethernet cables among notebook users.
    – njboot
    Commented Jun 25, 2014 at 19:52

As a matter of fact "Kanex" the only company I know of that offers "true" adapters put their Thunderbolt to eSATA + USB 3.0 adapter on the market 18 hours ago, at a price point of 69.95$

  • The Kanex USB 3 adapter would not work with USB 3 external hard drives that I bought it for so I had to return it. Make sure the place you buy it from has a decent return policy.
    – Mark
    Commented Nov 25, 2014 at 17:16
  • 2
    Does someone have real-life numbers for transfer speed, e.g. copying a few thousands files around 10 MB each from external disk to dev/null?
    – Nemo
    Commented Oct 22, 2015 at 13:47
  • @Nemo are you looking for benchmarks comparing Thunderbolt to USB 3.0 or benchmarks for the Kanex adapter?
    – Asmus
    Commented Oct 23, 2015 at 9:45
  • the adapter (or any Thunderbult to eSATA adapter really)
    – Nemo
    Commented Oct 23, 2015 at 16:37
  • the link seems to have broken, could this be fixed?
    – Zerium
    Commented Dec 14, 2016 at 6:09

I also ended up looking for good solutions. Thunderbolt 2 supports 20 Gb/s. So it could provide enough reserves for a real usb 3 hub where every port could finally run 5 Gb/s = 640 MB/s.

As a single SSD already exceeds the speed of a USB 3 connection, we should not put them through a USB 3 Hub bottleneck to not enforce slowing the transfer rates down.

Actually there are some companies that already considered these issues:

Other good manufacturers to check out:

  • Promise
  • OWC
  • G-Technology

All in all going for thunderbolt 2 is always on the much more expensive side of the table.


So, I believe the main reason these cables/adapters don't exist is explained in your question, actually. That is, the fact that many, if not all, devices that come with a Thunderbolt port, also already have one or more USB 3.0 ports.

If your primary concern is simply power draw on the bus, I'd recommend simply buying a powered USB 3.0 hub.

  • 4
    "devices that come with a Thunderbolt port, also already have one or more USB 3.0 ports"... except, of course, a couple of years' worth of Apple products, that came with a Thunderbolt port, but still only had USB 2, such as the Mac Mini, iMac and Macbook models of 2011-2013.
    – RCross
    Commented Apr 11, 2015 at 9:39
  • @RCross Mac mini 2012 has USB 3 ports, not USB 2. I don't know about the other devices in your list.
    – tubedogg
    Commented Jun 1, 2015 at 21:53
  • 2
    Macbook pro late 2011 has 2 USB 2 ports and Thunderbolt, no USB 3 :( Commented Jun 13, 2016 at 0:55

I have found the solution to my problem. I've got an eight port USB hub by Akasa, self powered. I connected four controllers, a sound card and two liscenses to it, while I use an USB 3.0 hub for my external drives. Works like a charm.


Thunderbolt T2 and USB3 are compatible as Apple device components. Market-place adapters may no work so well. Say you want to swap data from your Mac to the HP-PC business customer.

Apple-only T2 HighPoint RocketStar with 10 Gbps data transfer is no help, because half-speed PC's lack Thunderbolt technology. Universal UB3 StarTech STSDOCK2U33 may 'seem' more promising. Consider that fact that Mac/PC swap drive formatting is very tenuous.

Assuming anyone wants an external drive dock for a Mac, the only pro for half-speed StarTech over faster RocketStar is saving $136… Forget the swappable desktop drive dock idea, if possible. Why swap out data using a drive dock? USB is the best way for Mac/PC users to swap and co-produce compatible Microsoft Office and Adobe Creative Cloud data files.

Can you swap a external hard drive between Mac and pc without affecting it?

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .