This is 2019.

Is there any adapter that can display the video signal of a HDMI/DP device like a tv-box, PC or Notebook to a thunderbolt 3 Display?

The other way around doesn't count.

Edit: Delock has made it! It should be at least compatible with all USB-C Alt mode compatible displays.

They also have good HDMI male to DP female adapters with an extra usb for power on the HDMI side, not at 4k@60hz like on the first cable, but still.


2 Answers 2


Revised Answer:

After taking a closer look at USB-C or Thunderbolt 3 and how they achieve video output, I don't think an adapter exists to connect an HDMI video source to connect to a USB-C display. Even the official HDMI website shows the conversion as being one-way: USB-C to HDMI.

A major caveat is that sending HDMI over USB-C requires the video source to send additional signals that are not part of the HDMI specification; They're part of the USB-C specification.

For conversion in this direction to work, an adapter would have to be a USB-C Host controller and signal to the monitor that it wants to use the HDMI alternate mode. Creating a video adapter that acts as a USB-C host device is not trivial, and almost pointless since most devices or screens have multiple video connectors to use instead.

I believe that it may be possible to make such an adapter, but the demand for it is too low for any to exist yet.

Old Answer:

"This is 2019." Yes, but new video connectors don't always make things simpler.

To answer your question seriously, the thunderbolt 3 (USB-C) connection uses a DisplayPort signal for video. Unfortunately HDMI to DisplayPort (in that direction) is not compatible with just a simple wire-to-wire converter. You actually need something known as an "Active HDMI to Displayport Adapter", and obviously the displayport side needs to be the USB-C connector.

I am also fairly certain that the USB-C monitors get their power from the USB-C connection. If you have a monitor like that, the adapter would have to supply power too!

I have never seen an adapter that meets all of those requirements so I cannot recommend one for you.

It might be possible to combine two adapters:

  1. HDMI -> DisplayPort
    This one must be active, so requires its own power usually from USB.
  2. DisplayPort -> USB-C
    This one may be VERY hard to find in this direction but theoretically possible. (It probably doesn't exist.)

Old Update:

It turns out that I entirely missed that USB-C (and thunderbolt 3) can output HDMI signals too (as an Alternate Mode on top of USB-C). That implies that USB-C displays (but not necessarily ones that require Thunderbolt 3) can accept HDMI signals through that connector. This raises some hope that there is a passive HDMI to USB-C cable/adapter out there. (This isn't possible without negotiating the video mode over USB first.)

  • 1
    @KevinCrans, I'm reading elsewhere that a passive HDMI <--> USB-C cable did not work with an HP portable monitor, it will depend on the portable monitor you're using whether the passive cable could work, since some USB-C inputs don't accept HDMI. (I presume the ones that call themselves thunderbolt displays?)
    – Romen
    Aug 30, 2019 at 14:46
  • 1
    @KevinCrans, No info sorry. Here's the question on SuperUser that could actually be considered a duplicate of this. I suspect that HP screen just doesn't support HDMI over USB-C, but it might be hard to find since Thunderbolt and USB-C defined the DisplayPort mode first. Monitor manufacturers will probably opt for that as the "default" mode assuming the output is a USB-C port on the PC too.
    – Romen
    Aug 30, 2019 at 15:07
  • 1
    Actually the power can go both ways... There are enterprise-class displays which also work as USB hubs all the while charging your notebook. All over a single USB-C cable.
    – jaskij
    Sep 9, 2019 at 1:52
  • 1
    HDMI does not output power. So something like a laptop or TV box would not send power over an HDMI --> USB-C adapter. As mentioned earlier, this means the USB-C display would need its own power cable. Since this is a very unusual use-case for HDMI and USB-C, there just isn't any demand or reason to make an adapter that goes HDMI to USB-C for only video. People who buy that adapter might try to use it backwards and return the product in frustration because their USB-C or TB3 port wouldn't output HDMI video without a proper USB-C device on the other end.
    – Romen
    Nov 10, 2019 at 13:29
  • 1
    @KevinCrans, USB-C displays are almost exclusively intended to be used with laptops that have USB-C. Connecting them to other devices is not an expected use-case, and if too few people want to use the product that way, manufacturers won't consider it profitable to support those users by implementing non-standard functionality. (Like passive HDMI over USB-C) Also, USB-C can output 100W of power so it is often used for charging laptops and portable displays with batteries.
    – Romen
    Dec 10, 2019 at 21:02

Looks like Delock has made one explicitly called USB-C to bidirectional DP Alt mode Cable! Everyone, hooray for Delock!

  • 1
    This may work for many USB-C displays, but anyone looking at this recommendation should know that the cable does not support DisplayPort to Thunderbolt 3. DisplayPort via Thunderbolt-3 (on a USB-C connector) and DisplayPort Alternate Mode via USB-C are different video signals!
    – Romen
    Mar 3, 2020 at 18:04
  • Thank you for sharing your intel with us, TB3 is backwards compatible with USB-C Alt mode right? What you're saying is funny, because of how Virtuallink is different.
    – Ciel Ruby
    Mar 4, 2020 at 14:49
  • 1
    Thunderbolt 3 hosts are backwards compatible with USB-C, that is correct. But Thunderbolt 3 displays may be expecting a thunderbolt-format DisplayPort signal. It is possible that some "Thunderbolt 3" displays do not support USB-C Alt-Mode at all, because Thunderbolt 3 itself provides an alternative DisplayPort implementation.
    – Romen
    Mar 4, 2020 at 14:59
  • 1
    And VirtualLink is a USB-C alt mode. Not related to TB3 at all. Right now mostly video cards and specific ports on gaming laptops have support for VirtualLink, not all USB-C outputs!
    – Romen
    Mar 4, 2020 at 15:01
  • Good thinking! And thanks for sharing that last one as well, didn't got a clue.
    – Ciel Ruby
    Mar 4, 2020 at 15:04

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