HDMI 2.0 max refresh rate at 1080p, 1440p and 4K

HDMI 2.0 is enough for 1440p at 144 Hz, but only at 8-bit colour and with about 2% to spare. It is not enough for 1440p at 165 Hz or 240 Hz. At 1080p it carries up to about 246 Hz, and at 4K up to about 68 Hz. There is no compressed mode to fall back on, so anything past those limits needs DisplayPort or HDMI 2.1.

What limits HDMI 2.0

HDMI 2.0 is the HDMI version from 2013. HDMI Licensing's release gives it "increased bandwidth (up to 18Gbps)", enough for "4K@50/60". The HDMI Forum's release gives the same figures.

That 18 Gbps is not all picture. HDMI 2.0 sends 8 bits of picture as 10 bits on the wire, a scheme called 8b/10b. So only 80% of the link is picture data. Wikipedia's HDMI article lists a 600 MHz top character rate and a 14.4 Gbps data rate for HDMI 2.0. Both follow from the 18 Gbps:

The pixel clock is how many pixels the link sends per second. It counts the visible pixels plus blanking, the unseen gap a video signal leaves around each line and each frame. More blanking means a higher pixel clock for the same picture.

DSC (Display Stream Compression) is how newer links squeeze modes that do not fit. Wikipedia's HDMI article puts DSC support in HDMI 2.1. HDMI 2.0 does not have it. So on HDMI 2.0 a mode either fits uncompressed or it does not run.

Every mode against HDMI 2.0

We calculated pixel clocks with an open implementation of VESA's CVT 1.2 timing formula, in reduced blanking v2 mode. That mode uses 80 pixels of blanking per line and at least 460 microseconds per frame. It is the same method as our DSC and bandwidth article, and it reproduces that article's 1025.8 MHz for 1440p 240 Hz and 583.2 MHz for 1080p 240 Hz.

Turned around, this gives the top refresh at each resolution. We stepped the refresh up one hertz at a time until the pixel clock passed 600 MHz (8-bit) or 480 MHz (10-bit):

4K 120 Hz is out of reach by a long way. HDMI.org lists 4K120 among the modes of HDMI 2.1.

Worked case: a 165 Hz 1440p monitor on a laptop's HDMI 2.0 port

Take a 27-inch 1440p monitor rated for 165 Hz, and a laptop whose only video port is HDMI 2.0. Here is how the numbers decide it.

At 165 Hz the mode needs a 679.1 MHz pixel clock. At 8-bit that is 679.1 x 24 = 16.30 Gbps. The link carries 14.4. The mode is 13% too big, and with no DSC there is nothing to shrink it. 165 Hz will not run on this link.

Step down to 144 Hz and it needs 14.08 Gbps, which fits at 8-bit. So 144 Hz is the best this pair can do, if the monitor offers 144 Hz on its HDMI input. If you have set 10-bit colour, 144 Hz needs 17.6 Gbps and will not fit. Set 8-bit in the graphics driver first.

To get the full 165 Hz, change the link. DisplayPort 1.4 carries 25.92 Gbps of payload, per the DSC article, so 16.30 fits easily. If the laptop has a USB-C port that outputs DisplayPort, and the monitor has a DisplayPort input, that is the route.

144 Hz or 120 Hz: which answer is right

Two answers circulate. One KTC post says "HDMI 2.0 can run 1440p at 144 Hz without compression", but shows no maths. Another KTC post asks why HDMI 2.0 "caps at 1440p 120Hz". It calls 1440p 120 Hz the mode "that fits the connection".

The arithmetic says 144 Hz is right at 8-bit. It is a real fit, not a comfortable one: 586.6 MHz against 600. At 1440p 144 Hz the timing can hold at most 138 blank lines per frame, against the 103 that reduced blanking v2 uses. Or it can hold at most 140 blank pixels per line, against 80. A monitor whose own timing has more blanking than that will not reach 144 Hz on HDMI 2.0.

The 120 Hz answer persists for two reasons. At 10-bit, 1440p tops out at 119 Hz, so a 10-bit setup never sees 144. And the graphics card only offers modes the monitor reports for that input. If the monitor's HDMI input lists 120 Hz as its top, 120 Hz is all you get. In both cases what you see is real, but it is not a limit of HDMI 2.0 at 8-bit.

Where this stops applying

Every figure here is full RGB colour (4:4:4) at CVT reduced blanking v2. Monitors ship their own timings. A shorter blank lowers the pixel clock and a longer one raises it, which only matters for the close cases: 1440p 144 Hz and 1080p 240 Hz at 8-bit, and 1440p 120 Hz at 10-bit. Chroma subsampling modes, which send less colour data, are not covered. A link runs at its slower end, so an HDMI 2.1 card on a monitor with an HDMI 2.0 input is an HDMI 2.0 link. The worked case is arithmetic, not a test of any laptop or monitor. USB-C and Thunderbolt limits depend on the port and dock, and are left out. For what each refresh step is worth once it runs, see the refresh rate guide.

Sources

• HDMI Licensing, HDMI 2.0 specification release, September 4, 2013 (18 Gbps, 4K at 50/60).
• HDMI Forum, HDMI Forum releases version 2.0 of the HDMI specification, September 4, 2013.
• HDMI.org, HDMI 2.1 specification page (4K120).
• Wikipedia, HDMI (600 MHz character rate, 14.4 Gbps data rate, 8b/10b, DSC from HDMI 2.1).
• kevinlekiller, CVT 1.2 modeline calculator (reduced blanking v2 timings, run for every mode here).
• KTC, Can HDMI 2.0 Ports Handle 1440p at 144Hz Without Compression?, May 7, 2026.
• KTC, Why Does My HDMI 2.0 Cable Cap at 1440p 120Hz Instead of 4K?, June 15, 2026.