The data transfer speed of an HDMI to Type C adapter is not a fixed number—it depends entirely on the specific implementation of the adapter, the version of HDMI and USB-C standards involved, and the capabilities of your source device (like a laptop or phone) and display. In most cases, these adapters do not transfer data in the traditional sense (like file copying) but instead handle video signals. The speed is measured in terms of video bandwidth, which can range from 18 Gbps (for HDMI 2.0) up to 48 Gbps (for HDMI 2.1), but the USB-C side’s data lane configuration (like USB 3.2 Gen 2 or Thunderbolt 3/4) also plays a role. Let’s break this down with real numbers and technical details.
First, understand that an HDMI to Type C adapter typically converts HDMI video signals into a format that can be transmitted over a USB-C connector. However, the USB-C port on your device might support DisplayPort Alt Mode, which allows video signals to travel over the USB-C cable. If the adapter is passive (just a cable), it relies on the source device’s USB-C port supporting DisplayPort Alt Mode, and the video bandwidth is limited by the USB-C’s data lanes. For example, a standard USB 3.2 Gen 2 port has 10 Gbps of total bandwidth, but video signals can use up to 8.1 Gbps per lane (with four lanes in some configurations). In practice, most USB-C ports with DisplayPort Alt Mode can handle 4K at 60Hz (around 12.5 Gbps) or even 5K at 60Hz (around 20 Gbps) if using Thunderbolt 3 or 4, which offers 40 Gbps total bandwidth.
Now, if the adapter is active (with a built-in chipset), it might convert HDMI 2.0 or 2.1 signals to a USB-C format that supports higher resolutions. For instance, an hdmi to type c display adapter with a dedicated driver board can handle HDMI 2.0 input (18 Gbps) and output over USB-C with DisplayPort Alt Mode, supporting 4K at 60Hz (12.5 Gbps) or even 8K at 30Hz (around 16 Gbps). But the data transfer speed isn’t just about video—some adapters also include USB data passthrough (like USB 3.0 or 2.0) for peripherals, which adds another layer. For example, a common chipset like the IT6563 can handle HDMI 2.0 to USB-C conversion with up to 5.4 Gbps per lane for video, while the USB-C side might support USB 3.2 Gen 1 (5 Gbps) for data transfers. However, note that the video bandwidth and data bandwidth share the same physical lanes, so if you’re transferring files at 5 Gbps, the video quality might drop to 1080p at 60Hz.
Let’s look at specific scenarios with data. If you’re using a standard HDMI to Type C cable (passive) with a laptop that has a USB-C port supporting DisplayPort 1.2, the maximum video bandwidth is 17.28 Gbps (using four lanes at 4.32 Gbps each). This can handle 4K at 60Hz with 8-bit color (12.5 Gbps) or 1440p at 144Hz (around 14 Gbps). But if the adapter supports DisplayPort 1.4 (like many modern adapters), the bandwidth jumps to 32.4 Gbps (using HBR3, 8.1 Gbps per lane), enabling 4K at 120Hz or 8K at 60Hz with compression. For HDMI 2.1 to Type C adapters (which are rare but exist), the video bandwidth can reach 48 Gbps, but the USB-C port must support Thunderbolt 4 or USB4, which offer 40 Gbps total—so the actual limit is 40 Gbps. This means you can get 4K at 144Hz or 8K at 60Hz with Display Stream Compression (DSC).
Now, let’s talk about data transfer speed for non-video uses. Some HDMI to Type C adapters also include a USB hub or Ethernet passthrough, but the primary purpose is video. The data transfer speed for file transfers through the adapter’s USB-C port (if it has a passthrough) is typically limited to USB 2.0 (480 Mbps) or USB 3.0 (5 Gbps) depending on the design. For example, a cheap adapter might only support USB 2.0 for data, while a premium one with a dedicated chipset (like the VL103) can handle USB 3.2 Gen 1 at 5 Gbps. But if you’re using the adapter solely for video, the data transfer speed is irrelevant—you’re looking at video bandwidth.
Here’s a table to clarify the common speeds based on standards:
Table: Video Bandwidth and Data Transfer Speeds for HDMI to Type C Adapters
| Standard | HDMI Version | Max Video Bandwidth (Gbps) | USB-C Data Lane Speed | Max Resolution & Refresh Rate | Notes |
|----------|--------------|----------------------------|------------------------|-------------------------------|-------|
| Passive Cable | HDMI 1.4 | 10.2 | USB 3.2 Gen 2 (10 Gbps) | 4K at 30Hz (8.16 Gbps) | Limited by USB-C’s DisplayPort Alt Mode; no data passthrough |
| Active Adapter (Chipset) | HDMI 2.0 | 18 | USB 3.2 Gen 1 (5 Gbps) | 4K at 60Hz (12.5 Gbps) | Video uses 4 lanes; data uses 2 lanes; chipset like IT6563 |
| Active Adapter (Thunderbolt) | HDMI 2.0 | 18 | Thunderbolt 3 (40 Gbps) | 4K at 60Hz (12.5 Gbps) | Full bandwidth for video; data passthrough at 40 Gbps possible |
| Active Adapter (USB4) | HDMI 2.1 | 48 | USB4 (40 Gbps) | 8K at 60Hz (40 Gbps) | Requires DSC; video bandwidth limited to 40 Gbps by USB4 |
| Premium Adapter (DisplayPort 1.4) | HDMI 2.0 | 18 | USB 3.2 Gen 2 (10 Gbps) | 4K at 120Hz (18 Gbps) | Uses HBR3; data passthrough at 10 Gbps but shared lanes |
Notice that the data transfer speed for file transfers (like copying a movie) is separate from video bandwidth. If you plug a USB drive into the adapter’s USB-A port (if it has one), the speed is limited by the adapter’s USB controller. For example, most adapters with a USB 3.0 hub will give you 5 Gbps, but if you’re also streaming 4K video, the total bandwidth shared between video and data might drop to 10 Gbps total (USB 3.2 Gen 2), so video might take 8 Gbps, leaving only 2 Gbps for data. In practice, this means you won’t get full USB 3.0 speeds when using high-resolution video.
Another factor is the cable length and quality. For HDMI to Type C adapters, the cable itself can introduce signal degradation. A standard passive USB-C cable (like 1 meter) can handle 10 Gbps for data, but for video, it depends on the cable’s E-mark chip. If the cable is rated for USB 3.2 Gen 2 (10 Gbps), it can handle 4K at 60Hz. But a longer cable (2 meters or more) might drop to USB 2.0 speeds (480 Mbps) for data, and video might be limited to 1080p at 60Hz. Active cables (with built-in repeaters) can maintain 40 Gbps over 2 meters, but they’re more expensive.
Let’s get into the technical nitty-gritty. The HDMI to Type C adapter’s chipset (like the aforementioned IT6563 or the newer ANX7402) converts the HDMI signal into DisplayPort signals that can be sent over USB-C’s differential pairs. The HDMI input has 4 TMDS lanes (for HDMI 2.0) or 4 FRL lanes (for HDMI 2.1), each with a data rate of up to 6 Gbps (for HDMI 2.0) or 12 Gbps (for HDMI 2.1). The USB-C output uses 4 lanes of SuperSpeed data, each capable of 2.5 Gbps (for USB 3.2 Gen 1) or 5 Gbps (for USB 3.2 Gen 2). The chipset must map the HDMI lanes to the USB-C lanes, which introduces latency (typically under 1 millisecond). This latency doesn’t affect data transfer speed but can cause slight input lag for gaming.
For data transfer speed in terms of file copying, if you connect a USB-C to HDMI adapter to a computer and then plug a USB drive into the adapter’s USB-A port, the speed depends on the adapter’s USB controller. For example, the Realtek RTL9210 controller supports USB 3.2 Gen 2 (10 Gbps) but only if the adapter is designed for data passthrough. Most HDMI to Type C adapters are video-only, so they don’t have a USB hub. If you’re using a multi-function adapter (like a USB-C hub with HDMI output), the data transfer speed for the USB ports is typically 5 Gbps (USB 3.0) or 10 Gbps (USB 3.1 Gen 2), but the video bandwidth might be limited to 4K at 30Hz if the hub uses USB 3.0 for data.
Here’s a real-world example: Using a Dell XPS 13 (with Thunderbolt 3) connected to an HDMI to Type C adapter (like the Cable Matters Active Adapter), you can get 4K at 60Hz with 8-bit color. The data transfer speed through the adapter’s USB-C port (if you plug in a USB 3.0 drive) is 5 Gbps, but if you’re also streaming video, the total bandwidth is shared. In tests, this adapter achieves 4.5 Gbps for file transfers while displaying 4K video, which is close to the theoretical limit. For a passive adapter, the data transfer speed is zero because it doesn’t have a data passthrough.
Another important point: The data transfer speed of the HDMI to Type C adapter itself (as a device) is irrelevant if you’re just using it to connect a monitor. The adapter doesn’t store data; it’s a protocol converter. The speed you care about is the video bandwidth, which is determined by the HDMI version and the USB-C’s DisplayPort capability. For example, if your source device has HDMI 2.0 output and the adapter supports it, you’ll get 18 Gbps video bandwidth, which is enough for 4K at 60Hz. But if your source device only has HDMI 1.4, the adapter will be limited to 10.2 Gbps, so 4K at 30Hz.
Let’s also consider the Power Delivery (PD) aspect. Many HDMI to Type C adapters include PD passthrough, allowing you to charge your laptop while using the adapter. The PD speed is typically 60W to 100W (20V at 3A or 5A), but this doesn’t affect data transfer speed. However, the PD chipset (like the STUSB4500) can introduce noise that might reduce video bandwidth if not properly shielded. In practice, this is negligible.
For professionals who need high data transfer speeds, like video editors transferring large files, using an HDMI to Type C adapter for video output while also transferring data through the same USB-C port is not ideal. The shared bandwidth means you’ll get lower file transfer speeds. For example, if you’re copying a 10GB file at 5 Gbps, it takes about 16 seconds. But if you’re also displaying 4K video at 12.5 Gbps, the total bandwidth is 17.5 Gbps, which exceeds the USB-C’s 10 Gbps (if using USB 3.2 Gen 2). So the system will throttle the video to 1080p to free up bandwidth for data. This is a common issue with multi-function adapters.
To avoid this, use a dedicated HDMI to Type C adapter for video only, and a separate USB-C cable for data. Or use a Thunderbolt dock that provides dedicated lanes for video and data. Thunderbolt 3/4 offers 40 Gbps total, with 18 Gbps reserved for video (DisplayPort 1.2) and 22 Gbps for data (PCIe and USB). So you can transfer files at 22 Gbps (2.75 GB/s) while displaying 4K at 60Hz. This is the best case scenario.
In summary, the data transfer speed of an HDMI to Type C adapter is not a single number. For video, it’s 18 Gbps (HDMI 2.0) or 48 Gbps (HDMI 2.1), but limited by USB-C’s 40 Gbps (Thunderbolt/USB4). For data passthrough, it’s 5 Gbps to 10 Gbps (USB 3.0/3.1) or up to 40 Gbps (Thunderbolt). The actual performance depends on the chipset, cable quality, and source device. Always check the adapter’s specifications for HDMI version, USB-C data rate, and whether it supports DisplayPort Alt Mode. If you need a reliable adapter for high-resolution video, look for one with a dedicated driver board like the hdmi to type c display adapter that supports DP and PD functions, ensuring stable video bandwidth up to 4K at 60Hz or higher.