HDR Monitor Test
Check if your HDR monitor is working. Detects HDR support, wide color gamut, and includes peak-brightness, local-dimming, and gradient-banding test modes.
Detected capabilities
Detecting...
What is HDR on a monitor?
HDR (High Dynamic Range) on a monitor means the display can show brighter highlights, deeper shadows, and more colors at the same time than a standard SDR monitor. Standard SDR tops out around 250 nits and covers sRGB. HDR monitors target 400-1000+ nits and cover wider gamuts like DCI-P3.
HDR400 vs HDR600 vs HDR1000
VESA DisplayHDR tiers refer to peak sustained brightness:
- HDR400: 400 nits, 8-bit, no mandatory local dimming. Marketing label - experience is close to SDR.
- HDR600: 600 nits, 10-bit, local dimming required. Real HDR starts here.
- HDR1000: 1000 nits peak, proper local dimming. Full HDR experience.
- HDR True Black 400/500: OLED certification. 400 nits peak but infinite contrast.
HDR10, HDR10+, and Dolby Vision
These are the HDR metadata formats carried in video streams. HDR10 is the royalty-free baseline and is most common. HDR10+ and Dolby Vision use dynamic per-scene metadata for better tone mapping on dimmer displays.
Why my HDR monitor looks washed out
If HDR mode looks worse than SDR, possible causes: (1) HDR400 panel lacking true HDR capability, (2) Windows HDR calibration needed (Settings → Display → HDR), (3) running SDR content in HDR mode without proper gamut clamping, (4) low peak brightness in a bright room.
Read our full HDR monitor guide or check Color Gamut Test for wide-color-gamut testing.
Testing guide
How to test HDR on your monitor
This test reads your browser and display capabilities to report HDR, wide color gamut, and color depth support, then gives you fullscreen patterns for peak brightness, local dimming and blooming, and gradient banding so you can judge how your HDR actually performs, not just whether it is technically enabled.
Best for
- Confirming HDR is actually active after enabling it in Windows or macOS display settings.
- Checking for blooming or haloing around bright objects on a local-dimming LCD.
- Spotting 8-bit color banding in gradients that a real HDR panel should render smoothly.
How to run the test
- 1Check the detected capabilities panel first to confirm your browser reports high dynamic range and your target color gamut.
- 2Run the Peak Brightness pattern in a normal-lit room and judge how comfortable and bright the white appears.
- 3Run the Dark Scene pattern in a dim room and look for glow or blooming around the near-black discs.
- 4Run the Gradient Banding pattern and look for visible steps rather than a smooth transition from black to white.
How to read the result
If dynamic range reports Standard instead of High, HDR is not actually engaged, check your OS display settings and cable, not just the monitor menu.
Visible glow around the discs in the dark scene test means the local dimming zones are too coarse or too few for that content.
Visible banding in the gradient test points to an 8-bit panel or an 8-bit signal path rather than true 10-bit HDR output.
Related tools and guides
Frequently asked questions
Why does my browser say I have no HDR support even though my monitor is HDR?
The browser, operating system, cable, and monitor all need to agree on HDR. Check that HDR is switched on in Windows Display settings or macOS displays preferences, that you are using a DisplayPort or HDMI cable and port rated for it, and that you are on a Chromium-based browser like Chrome or Edge, since HDR detection support varies by browser.
What is the difference between HDR400, HDR600 and HDR1000?
These VESA DisplayHDR tiers describe peak brightness in nits. HDR400 requires only 400 nits and no mandatory local dimming, so it often looks like SDR with a label. HDR600 requires 600 nits and local dimming, where HDR starts to look meaningfully different. HDR1000 requires 1000 nits peak with real local dimming for the full effect.
Why does HDR mode look washed out or worse than SDR?
This usually happens on HDR400 panels that lack real local dimming and enough peak brightness to deliver what HDR content expects. It can also happen if Windows HDR calibration has not been run, or if SDR content is being displayed in HDR mode without correct gamut clamping.
What is blooming in an HDR test?
Blooming is a halo of light that spreads from a bright object into the surrounding dark area, caused by a local dimming zone lighting up a region larger than the bright object itself. Fewer, larger dimming zones produce more visible blooming than a dense Mini-LED array.
Does gradient banding mean my monitor is broken?
No. Banding in a black-to-white gradient usually just means the panel or its current signal path is 8-bit rather than 10-bit. It is a normal limitation of many SDR and entry-level HDR monitors, not a defect.
Testing guide
How to test HDR on your monitor
This test reads your browser and display capabilities to report HDR, wide color gamut, and color depth support, then gives you fullscreen patterns for peak brightness, local dimming and blooming, and gradient banding so you can judge how your HDR actually performs, not just whether it is technically enabled.
Best for
- Confirming HDR is actually active after enabling it in Windows or macOS display settings.
- Checking for blooming or haloing around bright objects on a local-dimming LCD.
- Spotting 8-bit color banding in gradients that a real HDR panel should render smoothly.
How to run the test
- 1Check the detected capabilities panel first to confirm your browser reports high dynamic range and your target color gamut.
- 2Run the Peak Brightness pattern in a normal-lit room and judge how comfortable and bright the white appears.
- 3Run the Dark Scene pattern in a dim room and look for glow or blooming around the near-black discs.
- 4Run the Gradient Banding pattern and look for visible steps rather than a smooth transition from black to white.
How to read the result
If dynamic range reports Standard instead of High, HDR is not actually engaged, check your OS display settings and cable, not just the monitor menu.
Visible glow around the discs in the dark scene test means the local dimming zones are too coarse or too few for that content.
Visible banding in the gradient test points to an 8-bit panel or an 8-bit signal path rather than true 10-bit HDR output.
Related tools and guides
Frequently asked questions
Why does my browser say I have no HDR support even though my monitor is HDR?
The browser, operating system, cable, and monitor all need to agree on HDR. Check that HDR is switched on in Windows Display settings or macOS displays preferences, that you are using a DisplayPort or HDMI cable and port rated for it, and that you are on a Chromium-based browser like Chrome or Edge, since HDR detection support varies by browser.
What is the difference between HDR400, HDR600 and HDR1000?
These VESA DisplayHDR tiers describe peak brightness in nits. HDR400 requires only 400 nits and no mandatory local dimming, so it often looks like SDR with a label. HDR600 requires 600 nits and local dimming, where HDR starts to look meaningfully different. HDR1000 requires 1000 nits peak with real local dimming for the full effect.
Why does HDR mode look washed out or worse than SDR?
This usually happens on HDR400 panels that lack real local dimming and enough peak brightness to deliver what HDR content expects. It can also happen if Windows HDR calibration has not been run, or if SDR content is being displayed in HDR mode without correct gamut clamping.
What is blooming in an HDR test?
Blooming is a halo of light that spreads from a bright object into the surrounding dark area, caused by a local dimming zone lighting up a region larger than the bright object itself. Fewer, larger dimming zones produce more visible blooming than a dense Mini-LED array.
Does gradient banding mean my monitor is broken?
No. Banding in a black-to-white gradient usually just means the panel or its current signal path is 8-bit rather than 10-bit. It is a normal limitation of many SDR and entry-level HDR monitors, not a defect.