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HDR Support Check

Find out whether your display is running HDR — and what that certification actually guarantees.

How this test works

The browser exposes display capability through CSS media queries, and this reads them directly: `dynamic-range: high` for the page rendering context, `video-dynamic-range: high` for the video decode path, and `color-gamut` for the widest colour space the display will claim. Those queries are re-read whenever the display changes, because HDR is a toggle that can flip while the page is open — on Windows it is a settings switch, and laptops often drop HDR on battery. What the tool then refuses to do is convert a positive answer into a pass, because the certification behind it is weak enough that a positive answer routinely describes a panel you cannot tell from SDR.

What the results mean

Page dynamic range
Whether HDR is available for ordinary page rendering. Separate from video, and browsers handle the two differently on purpose.
Video dynamic range
Whether the video decode path can deliver HDR. This is often the only one that is true, which is why HDR films play correctly while the desktop looks unchanged.
Colour gamut
The widest colour space the browser will claim: sRGB, P3 or Rec. 2020. Wide gamut and HDR are independent — a display can have either without the other.
Peak brightness / dimming zones
Reported as not exposed, because they are. These decide whether HDR is visible, and no browser API provides them.

Common problems and fixes

Windows says my monitor is HDR but this reports standard
HDR in Windows is per-display and off by default. Settings, System, Display, then Use HDR for the correct monitor. It only appears if the display and the current connection both support it.
HDR works for video but not for anything else
That is a deliberate design in several browsers and operating systems, and this tool reports the two paths separately so you can see it. The video path gets HDR because the content carries its own metadata.
It turned off when I unplugged the laptop
Many laptops disable HDR on battery because it costs significant power at the panel. Plug in and re-run.

Frequently asked questions

Does this mean my monitor has real HDR?

It means the pipeline will accept an HDR signal. Whether the panel does anything with it is a separate question that comes down to peak brightness and local dimming, and no web page can measure either. DisplayHDR 400 panels report exactly the same as DisplayHDR 1000 ones here.

Why is HDR400 criticised so much?

Because it certifies a specification that a good standard-range monitor already meets: 400 nits peak, no local dimming required, no wide gamut required. The logo is accurate and the experience is close to unchanged, which is why the two are worth separating.

Is wide colour gamut the same as HDR?

No, and they are reported separately here for that reason. Gamut is how many colours the display can show; dynamic range is how bright and dark it can go. A P3 monitor with no HDR is common, and so is the reverse.

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