What a pass looks like at 120 Hz
At 120 Hz a new frame arrives every 8.33 ms, so the frame-time chart should run flat along that line and the verdict should read Pass. A reading of exactly 60 means something is halving the rate: a setting, power saving or the connection, never a “slow” 120 Hz panel. Readings between 60 and 120, or a chart that jumps between 8.3 and 16.7 ms, usually mean the screen is switching rates on its own, which is what Windows’ dynamic refresh rate does. For the general steps, see the refresh rate test.
The motion test is the quick check by eye: next to the 60 fps row, a screen really at 120 shows the top object visibly crisper. If all rows look the same, you’re at 60.
Laptops with a 120 Hz panel
Many laptops with a 120 Hz screen don’t hold it. Windows 11’s Dynamic refresh rate needs a screen with variable refresh rate and at least 120 Hz, and Microsoft describes it as adjusting the rate to what you are doing, keeping it high for gaming, browsing or inking and saving battery on lighter work (as of October 2026). Microsoft also notes that it can limit the refresh rate of games not made for variable refresh, and that the fix is to turn it off. To test the panel itself:
- Open Start, Settings, System, Display, Advanced display.
- Pick 120 Hz under Choose a refresh rate, and turn Dynamic refresh rate off while you test.
- Plug in the charger and turn battery saver off, so power saving plays no part in the reading.
On a MacBook Pro, use Chrome or Firefox: Safari keeps web pages near 60 fps, and the verdict then shows the browser’s limit rather than the screen’s.
A TV at 120 Hz from a computer
A TV only shows 120 Hz from a computer if every link in the chain carries it. With the same VESA timing the verdict uses, 1080p at 120 Hz needs about 6.6 Gbps of video, which even HDMI 1.4 carries, and 1440p about 11.6 Gbps (HDMI 2.0). 4K at 120 Hz needs about 25.8 Gbps at 8 bits per color, more than HDMI 2.0’s 14.4 Gbps, so it takes a full 48 Gbps HDMI 2.1 output, an HDMI 2.1 input on the TV and an Ultra High Speed HDMI cable, which HDMI Licensing describes as the cable for systems of up to 48 Gbps.
Things to check, in this order:
- The input. Check which of the TV’s HDMI ports its manual lists for 4K at 120 Hz, and use that one.
- The TV’s HDMI setting. If the TV has an enhanced or high-bandwidth HDMI option for that port, turn it on; the manual gives its name.
- The computer. Pick 120 Hz for the TV in Windows’ Advanced display settings or in the graphics driver’s control panel. If 120 Hz is only offered at a lower resolution, the link is the limit: the table under What 120 Hz needs from the connection below shows which ports carry each resolution.
Phones and other rates
Phones and tablets at 120 Hz have their own pages, because their browsers and battery settings are the usual limit: the iPhone 120 Hz test and the Android refresh rate test. A monitor rated 144 Hz belongs on the 144 Hz test.
What 120 Hz needs from the connection
The video data a monitor needs grows with its resolution and refresh rate. This table works it out for 120 Hz with VESA’s reduced-blanking timing (CVT-RB2), the tightest standard timing, and compares it with what each connection carries after its line coding. It shows the oldest version that carries the signal uncompressed at 8 bits per colour, then at 10 bits (HDR).
The graphics card’s output and the monitor’s input must both support that version, with a cable certified for the speed: High Speed HDMI (10.2 Gbps), Premium High Speed (18 Gbps), Ultra High Speed (48 Gbps).
| Resolution at 120 Hz | Video data | DisplayPort | HDMI |
|---|---|---|---|
| 1080p1920 × 1080 | 6.6 Gbps10-bit: 8.2 Gbps | 1.2 or newer | 1.4 or newer10-bit: 2.0 or newer |
| 1440p2560 × 1440 | 11.6 Gbps10-bit: 14.5 Gbps | 1.2 or newer | 2.0 or newer10-bit: 2.1 |
| Ultrawide 1440p3440 × 1440 | 15.5 Gbps10-bit: 19.3 Gbps | 1.2 or newer10-bit: 1.4 or newer | 2.1 |
| 4K3840 × 2160 | 25.8 Gbps10-bit: 32.3 Gbps | 1.4 (only just) or newer10-bit: 2.1 UHBR10 or newer, or 1.4 with DSC | 2.1 |
“Only just” means the signal fits with the standard timing but leaves under 5% to spare, so a monitor with looser timings of its own may stop short on that link: its manual has the final word. “With DSC” and “DSC only” refer to Display Stream Compression, which VESA added in DisplayPort 1.4 and describes as visually lossless; the monitor and graphics card both have to support it.
HDMI 2.1 ports run at 18 to 48 Gbps; the figures assume a full 48 Gbps port: check the monitor’s and card’s specs. Every HDMI 2.1 feature is optional, so a port sold as HDMI 2.1 may run no faster than HDMI 2.0.
| Connection | On the wire | Left for video |
|---|---|---|
| HDMI 1.4 | 10.2 Gbps | 8.16 Gbps |
| HDMI 2.0 | 18 Gbps | 14.4 Gbps |
| HDMI 2.1 | 48 Gbps | 42.67 Gbps |
| DisplayPort 1.2 | 21.6 Gbps | 17.28 Gbps |
| DisplayPort 1.4 | 32.4 Gbps | 25.92 Gbps |
| DisplayPort 2.1 (UHBR10) | 40 Gbps | 38.69 Gbps |
| DisplayPort 2.1 (UHBR13.5) | 54 Gbps | 52.22 Gbps |
| DisplayPort 2.1 (UHBR20) | 80 Gbps | 77.37 Gbps |
Sources: HDMI Licensing Administrator (HDMI 1.3 announcement: 340 MHz, 10.2 Gbps, the speed HDMI 1.4 keeps; HDMI 2.0: 18 Gbps; cable types: 10.2, 18 and 48 Gbps; HDMI 2.1 labelling: optional features) and VESA (DisplayPort 2.0 announcement: 25.92 Gbps of payload for DisplayPort 1.4, 77.37 Gbps for UHBR20). HDMI up to 2.0 and DisplayPort 1.x lose 20% to 8b/10b coding, HDMI 2.1’s fixed-rate link 11% (16b/18b over 3 or 4 lanes of 3 to 12 Gbps, Granite River Labs) and DisplayPort 2.1 about 3%.