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Do you need HDMI 2.1 for 4K 120Hz? Cable and bandwidth requirements

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.

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.

By TechCompare · Updated

Required bandwidth
33.4 Gbps
Uncompressed
With DSC
8.9 Gbps
Visually lossless 3:1
Mode
3840×2160 @ 120 Hz
10-bit 4:4:4

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.

Uncompressed Signal33.4 Gbps
With Display Stream Compression (DSC)8.9 Gbps

DSC uses visually lossless 3-to-1 compression, shrinking the required bandwidth so it fits through older cables.

Cable Limits Reference
HDMI 2.0
14.4 Gbps
⚠ DSC required
DP 1.4
25.9 Gbps
⚠ DSC required
HDMI 2.1
42.6 Gbps
✓ Native support
DP 2.1 (UHBR 20)
77.4 Gbps
✓ Native support
Display Mode: 3840 × 2160 @ 120 Hz
Color depth: 10-bit 4:4:4

Calculator

Display Bandwidth Calculator

Required Bandwidth

Uncompressed

33.44 Gbps

With DSC (Display Stream Compression)

8.92 Gbps

Interface Compatibility

HDMI 1.4
✗ Incompatible
HDMI 2.0
DSC Required
HDMI 2.1 (48G)
✓ Native
HDMI 2.2 (96G)
✓ Native
DisplayPort 1.2
DSC Required
DisplayPort 1.4
DSC Required
DisplayPort 2.1 (UHBR 10)
✓ Native
DisplayPort 2.1 (UHBR 13.5)
✓ Native
DisplayPort 2.1 (UHBR 20)
✓ Native
This exact 3840×2160 @ 120 Hz signal, pre-loaded. Swap the resolution, refresh, or chroma, or compare two modes.
Edit in the full tool

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

The 33.4 Gbps the mode needs sits 22% below HDMI 2.1's effective 42.6 Gbps ceiling, which is exactly the headroom the spec was designed around for variable-rate timing overhead and modern GPU metadata. HDMI 2.0's 14.4 Gbps can't carry it even with aggressive 4:2:0 chroma, which is why PS5 and Xbox Series X require HDMI 2.1 cables for their 4K 120 Hz modes. The DSC-free path is what keeps input latency identical to a simple 4K 60 signal, which matters for competitive console play where the compression latency of fallback paths is a real concern.

More HDMI 2.1 scenarios

HDMI 2.1 - 4K 60 Hz
4K at 60 Hz with 8-bit 4:4:4 color needs 13.4 Gbps of uncompressed bandwidth.
View details ➜
HDMI 2.1 - 4K 144 Hz HDR
4K 144 Hz with 10-bit 4:4:4 HDR needs 40.1 Gbps, within 6% of HDMI 2.1's effective 42.6 Gbps ceiling.
View details ➜
HDMI 2.1 - 8K 60 Hz (4:2:0)
8K at 60 Hz with 10-bit 4:2:0 chroma works out to 33.4 Gbps, the uncompressed figure HDMI 2.1 was carefully engineered to support.
View details ➜

Related guides

55" 16:9 TV screen size
Common 4K 120 Hz OLED TV size that needs HDMI 2.1.
View guide ➜
55" 4K TV PPI
PPI at 4K 120 Hz on a 55-inch TV.
View guide ➜

Frequently asked questions

Does PS5 require HDMI 2.1 for 4K 120Hz?
Yes, to output 4K at 120Hz in full HDR, you must use the supplied HDMI 2.1 cable and connect it to an HDMI 2.1 port on your TV or monitor.
Does HDMI 2.0 support 4K at 120Hz?
No, HDMI 2.0 does not have enough bandwidth for 4K 120Hz at full quality. It can only support 4K 120Hz if you lower the resolution or drop chroma subsampling heavily.
Does Xbox Series X output 4K 120 Hz over HDMI 2.1?
Yes. The Series X has a certified HDMI 2.1 port and ships with a cable rated for 48 Gbps. The console negotiates 4K 120 Hz with 10-bit 4:4:4 (33.4 Gbps) natively, well within HDMI 2.1's headroom. No DSC compression is needed.
What happens if I use an HDMI 2.0 cable for 4K 120 Hz?
The signal won't fit. HDMI 2.0 tops out at 14.4 Gbps effective, while 4K 120 Hz 10-bit 4:4:4 needs 33.4 Gbps. The display either falls back to 4:2:0 chroma (which degrades text edges), drops to a lower refresh, or shows no signal. Use a certified Ultra High Speed HDMI 2.1 cable.

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