Do you need HDMI 2.1 for 4K 120Hz? Cable and bandwidth requirements
4K 120 Hz with 10-bit 4:4:4 color HDR needs 33.4 Gbps, the benchmark mode HDMI 2.1 was designed to support without compression. It sits 22% below HDMI 2.1's effective 42.6 Gbps ceiling, giving just enough headroom for the variable-rate timing overhead modern GPUs use.
Interface Bandwidth Analysis
See how much uncompressed and compressed bandwidth this resolution and refresh rate mode demands, compared to the native limits of common video cables.
DSC uses visually lossless 3-to-1 compression, shrinking the required bandwidth so it fits through older cables.
Calculator
Display Bandwidth Calculator
Required Bandwidth
Uncompressed
33.44 Gbps
With DSC (Display Stream Compression)
8.92 Gbps
Interface Compatibility
How this is calculated
This is the mode that made HDMI 2.1 matter. HDMI 2.0 tops out at 14.4 Gbps and can't reach it even with 4:2:0 chroma. You have to drop either refresh or bit depth. HDMI 2.1 handles it natively without Display Stream Compression, which is why PS5 and Xbox Series X require HDMI 2.1 cables for their 4K 120 Hz output modes.
Verdict
33.4 Gbps is squarely in HDMI 2.1's wheelhouse. Any certified Ultra High Speed HDMI cable (48G) drives this mode without DSC, keeping latency identical to a simpler 4K 60 signal.
More HDMI 2.1 scenarios
Frequently asked questions
Does PS5 require HDMI 2.1 for 4K 120Hz?
Does HDMI 2.0 support 4K at 120Hz?
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