The short answer to the question “does HDMI support 240Hz?” is a yes. Yes HDMI CAN support 240Hz. However, the more comprehensive answer is that it depends upon the version of the HDMI your PC supports as well as the resolution and color bit depth of your monitor.
240Hz refresh rate, as we know, really pushes the limit of what the monitors can achieve. In fact only the best and top of the line monitors support such high refresh rates.
However, in order to support such high refresh rates, you not only need a powerful graphics to push those 240 frames, but also the right HDMI port and cable.
If you have an older PC with the older HDMI 1.4 port, then unfortunately, such high refresh rates will simply not be supported. If you have a newer PC with the newer HDMI 2.0 port, then there is a high chance that you will have no issue supporting 240 Hz refresh rate.
But then again, it depends upon the resolution you wish to play on and the colors your monitor can display and in the following text I will explain this all.
Refresh Rate, Resolution and Color Bit Depth Affect Bit Rate
Before you delve deeper into whether the refresh rate of 240Hz is supported by your HDMI interface, you have to understand a few key concepts.
For starters know that there are different versions of the HDMI protocol. Each version has a different amount of bandwidth it can carry. The following table shows this.
|HDMI Version||Max Resolution||Max Refresh Rate||Max Bandwidth|
|HDMI 1.0||1080p||1080p @ 60 Hz||4.95||3.96||No||- 8 Audio Channels|
|HDMI 1.1/1.2||1440p||1440p @ 30 Hz||4.95||3.96||No||- 8 Audio Channels
-Super Audio CDs
|HDMI 1.3/1.4||4096 x 2160 (4K)||120 Hz @ FHD Resolution|
30 Hz @ 4k Resolution
24 Hz @ 4k Resolution
|10.2||8.16||No||- 8 Audio Channels
- Dolby TrueHD
|HDMI 2.0||4096 x 2160 (4K)||60 Hz @ 4K Resolution||18||14.40||Yes||- 32 audio channels,
- Dynamic Resolution Adaptation (DRA)
- High-Efficiency Advanced Audio Coding (HE-AAC)
|HDMI 2.1||Upto 10240 x 4320 (10K)||Upto 120Hz @ 10K||48||42.67||Yes||- 32 audio channels
Also Read: How to Check HDMI Port Version?
The most important parameter here is the Effective Bandwidth of the HDMI version. If you think of HDMI version as a pipeline carrying water, then Effective Bandwidth pertains to the amount of water it can carry in a second.
Now if the data you transfer (data rate) exceeds the supported amount by the particular HDMI version, then the overall performance will be affected in the form of stutters, freezes or simply lower than expected frame rate.
In other words, if you send 12 Gbit/s of data over an HDMI 1.4 interface, then the performance will be affected. However, if the same is transferred over an HDMI 2.0 interface, then you will have no issues at all
There are three important parameters that determine the bit rate or the amount of data your display interface is generating or carrying.
- The Resolution
- Refresh Rate
- Color Bit Depth
The higher the resolution, the refresh rate or the color bit depth, the more data is being carried.
Color bit depth of a monitor basically pertains to the amount of colors it can show. Normal monitors have an 8-bit color depth. These have the potential to show 16.7 million colors.
Professional monitors have a 10-bit color depth which can show 1 billion colors. Even more robust monitors have a 12-bit color depth.
So the higher the color bit depth, the higher is the data rate generated by your video interface.
Calculating Your Bit Rate
To calculate the data transfer rate for your desired refresh rate and resolution you can use the following equation.
(H + Hblank) × (V + Vblank) × (C x 3) × F
In this equation,
- H is horizontal pixel count
- V is vertical pixel count
- C is the color depth
- F is the refresh rate
- Hblank is the Horizontal blanking interval
- Vblack is the Vertical blanking Interval
Note on Blanking Intervals:
Blanking Interval is the time between the last line scanned of a frame and the first line scanned of a frame. You don’t need to know this indepth for the purpose of this article. For CVT-RB Format,
- Hblank = 80 pixels for FHD @ 60 Hz
- Vblank = 30 Pixels for FHD @ 60 Hz
- Vblank = 134 Pixels for FHD @ 240 Hz
You can also use online calculators to determine the data rate. Such as this very popular calculator
So Does HDMI Support 240Hz?
Given the equation above and since we know the effective data rate each HDMI version can carry, we can determine whether a certain HDMI version can support 240Hz refresh rate or not.
Here for instance, I will use 1920×1080 resolution and take 8 bit as the color depth of my monitor.
(H + Hblank) × (V + Vblank) × (C x 3) × F
(1920 + 80) × (1080 + 134) × (8 x 3) × 240
= 13,985,280,000 bits per second / 1,000,000,000 (to get this into Gbit/s)
Therefore, running 240 Hz on Full HD resolution on an 8 bit monitor will generate about 14 Gbit/s of data. Hence you will need at least an HDMI 2.0 interface in order to support this fully.
HDMI 1.4 would be a bottleneck here if you run these settings on an HDMI 1.4 port and perhaps the video will simply not work with an HDMI 1.4.
What about higher resolution and color depth? What HDMI version would you require if running at 240 Hz?
The following table explain this:
|240Hz||1920x1080 (FHD)||8||14||HDMI 2.0|
|240Hz||2560x1440 (QHD)||8||24.62||HDMI 2.1|
|240Hz||3840x2160 (UHD/4K)||8||54.97||HDMI 2.1 with DCS|
|240Hz||1920x1080 (FHD)||10||17.50||HDMI 2.1|
|240Hz||2560x1440 (QHD)||10||30.77||HDM 2.1|
|240Hz||3840x2160 (UHD/4K)||10||68.56||HDM 2.1 with DCS|
You can see from the table above that an HDMI 2.0 can support 240 Hz refresh rate only at 1920×1080 Full HD resolution and on an 8-bit monitor.
Any higher resolution or a higher bit rate monitor would saturate the HDMI 2.0 interface.
If you wish to play on 240 Hz monitor with higher than FHD resolution, then you will need to have the HDMI 2.1 interface.
Here is the summary:
|HDM 2.0||Yes||- 240Hz @ 1920x1080|
|HDM 2.1||Yes|| - 240Hz @ 2560 x 1440
- 240Hz @ 3840 x 2160 with DCS
Does HDMI 2.0 Support 240Hz?
Yes, both HDMI 2.0a and HDMI 2.0b can support 240Hz refresh rate or 240 FPS at 1920×1080 resolution given that you have an 8 bit monitor.
Does HDMI 1.4 Support 240Hz Monitor?
The data rate 240Hz generates is higher than that supported by HDMI 1.4. While the monitor will work, the HDMI 1.4 interface will be a bottleneck and thus limit the maximum potential frame per second you can get.
Can HDMI Support 4K 240Hz?
No, not without DCS support. From the above discussion we can see that 4K @ 240Hz generates 68.46 Gbit/s of data. This far exceeds the maximum carrying capacity of HDMI 2.1.
However, certain HDMI 2.1 cables that support VESA’s Data Stream Compression algorithm can support 4K @ 240Hz or even higher depending upon the ratio of compression.
VESA DSC can have a compression ratio of upto 3:1 meaning, HDMI 2.1 can support 3 times as much as its maximum effective transfer rate with this technology.
How Do I Get 240Hz on My Monitor?
Firstly, you need to have a monitor that supports 240Hz refresh rate. Secondly, you need to have the right cable and the version to enable the support for 240Hz refresh rate.
You not only need to have the right ports, but also the right cable. For instance, when running at 4K @ 240Hz, you will not only need HDMI 2.1 ports on the monitor as well as on the PC, but you will need to have an HDM 2.1 cable.
Also Read: How to Check HDMI Cable Version?
So does HDMI support 240Hz? Yes, HDMI 2.0 and newer version can support 240Hz refresh rate.
However, the exact version you would require in order to fully support 240Hz refresh rate depends upon the resolution and the color depth of your monitor.