HDMI versions define how much bandwidth the link carries and which features it supports. The version number on a device tells you its capabilities; the cable must be rated to carry the bandwidth those capabilities need. Both ends and every device in between must support a feature for it to work.
Versions at a glance
| Version | Max bandwidth | Headline capability | Key features added |
|---|---|---|---|
| 1.4 | 10.2 Gbps | 4K30 | ARC, HEC, 3D, HDMI Ethernet |
| 2.0 | 18 Gbps | 4K60 4:4:4 8-bit | Wide color, 32 audio channels |
| 2.0a / 2.0b | 18 Gbps | + HDR | Static HDR (HDR10), HLG (2.0b) |
| 2.1 | 48 Gbps | 4K120 / 8K60 | VRR, ALLM, eARC, Dynamic HDR, QMS |
The bandwidth figure is the total signalling rate. Usable video bandwidth is lower after 8b/10b (v2.0) or 16b/18b (v2.1) encoding overhead — roughly 14.4 Gbps usable on 2.0, 42 Gbps on 2.1.
What each version enables
- 1.4 — 4K but only at 30 Hz; fine for signage and non-motion content. Introduced the Audio Return Channel (ARC).
- 2.0 / 2.0a / 2.0b — the workhorse for 4K60. Handles 4K60 at full 4:4:4 chroma and 8-bit color, or 4K60 10-bit HDR at reduced 4:2:2/4:2:0 chroma. 2.0a added HDR10; 2.0b added HLG.
- 2.1 — jumps to 48 Gbps, enabling 4K120 and 8K60 at full color depth, plus gaming and audio features: VRR (variable refresh), ALLM (auto low-latency mode), eARC (high-bitrate audio return), and QMS (quick media switching to kill mode-change blackouts).
Cable categories (the part that trips people up)
| Cable rating | Certified bandwidth | Supports |
|---|---|---|
| Standard | ~4.95 Gbps | 1080i / 720p |
| High Speed | 10.2 Gbps | 4K30, 1080p |
| Premium High Speed | 18 Gbps | 4K60 HDR |
| Ultra High Speed | 48 Gbps | 4K120, 8K60 |
“HDMI 2.1” is not a cable spec — the correct cable is Ultra High Speed. A device can be HDMI 2.1 while only implementing a subset of 2.1 features, so confirm the specific feature (e.g. 4K120, eARC) is supported, not just the version number.
Practical notes
- Passive copper HDMI is short. Full-bandwidth 4K60/48 Gbps runs are reliable to only a few metres. For longer runs use active optical HDMI, HDBaseT, or AV-over-IP.
- Chroma trades against bandwidth. When a link can’t carry full 4:4:4, sources drop to 4:2:2 or 4:2:0 — see Chroma Subsampling.
- HDR needs the whole chain. HDR also requires HDCP 2.2 and a display that advertises it in EDID.
Related
- HDR Formats · HDCP · EDID Explained
- Estimating link/network load? Use the Bandwidth Calculator.
Sources
- HDMI Forum / HDMI Licensing Administrator — HDMI Specification 2.1b, 2.0, and 1.4 (bandwidth and feature definitions).
- HDMI Cable categories — Standard, High Speed, Premium High Speed, and Ultra High Speed cable certification programs.