HDR test. What the browser is offered.
An HDR screen with HDR switched off in the system shows nothing in HDR, and most people never find out. This asks the browser what it is being offered: high dynamic range or not, and which colour gamut. It cannot measure a nit, and says so; it can tell you whether the switch is on.
One check
- HDR and wide colour
One check after another, with your progress along the top and a plain verdict on each. Nothing you show the camera or say into the microphone leaves this page.
What it measures
Measured here, not assumed.
- HDR offered
- Whether the system is giving the browser a high dynamic range surface. Off is the usual finding on an HDR capable screen.
- Colour gamut
- sRGB only, Display P3, or Rec. 2020, as the browser reports it. Firefox reports none, which is not a verdict on the screen.
- Colour depth
- Bits per pixel as the system reports it; 30 or more on a wide gamut screen.
If it fails
The usual failures, and what fixes each.
- HDR capable but reads off
- Turn HDR on in the system's display settings; the path for your device is shown under the fixes on this page. On macOS it is automatic on supported displays. Then run again.
- Reads on but content looks flat
- Windows has an SDR content brightness slider under the HDR settings; raise it. Some screens need HDR mode chosen in their own menu too.
- Not HDR capable
- Then off is correct and costs nothing for ordinary use. Do not turn HDR on for a screen that only accepts the signal; it looks worse.
Where a browser stops
What it cannot tell you.
- A page cannot measure peak brightness, contrast or the panel's true gamut. It reads what the browser is offered, which is the switch, not the screen.
- Firefox does not report HDR or the gamut, so it reads as unknown there.
- Chrome and Edge show HDR content only when the system has HDR on; that is the switch this finds.
Privacy
Nothing leaves this page.
The camera and microphone are read on this page and stopped as soon as they have been measured. The clip you can play back lives in the browser's memory and is discarded when you leave. The location check discards the position. The internet test sends random bytes to this site and nothing else. The result is stored nowhere unless you ask for it by email, and then only the fact that an email was sent is kept.
Questions
HDR test, answered
- How do I check if HDR is on?
- Run this. It reports whether the browser is being offered HDR, which is exactly the system switch. If the screen is HDR capable and this reads off, the switch is off.
- Why does HDR look washed out on Windows?
- Because standard content is shown at a fixed brightness inside the HDR range. Raise the SDR content brightness slider in the HDR settings, and check the screen's own HDR mode.
- Can a browser measure HDR brightness?
- No. It can ask whether HDR is offered and which gamut, and nothing more. Peak brightness needs a meter on the screen.
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