Colour gamut test. The switch, not the screen.
A wide-gamut screen only shows wide colour when the system and the browser pass it through. This test reads which gamut the browser is given, whether it can draw Display P3 and Rec. 2020 colours, and then shows paired swatches: an inner square more saturated than sRGB can hold, inside the most saturated sRGB colour. If the wider colour reaches you, the inner square stands out. It cannot measure the panel, and says so.
One check · Your eyes
Asks for: Nothing. It runs in its own window and nothing leaves this page.
In short
Colour gamut test: the answer first
A colour gamut test in a browser can read which gamut the system gives the browser, sRGB, Display P3 or Rec. 2020, and show colours past sRGB for your eyes to judge. It cannot measure the panel's coverage or accuracy; that needs a colorimeter, and this page never prints a percentage.
Reading your result
- Reported wide, seen richer
- Wide colour reaches you: the panel, the system and the browser all pass it through.
- Reported sRGB
- Either the panel is sRGB, which is normal, or a wide panel is not being passed through. The steps under the result cover the system settings.
- Reported wide, seen the same
- Check the angle, the brightness and the screen's own sRGB mode before anything else.
What it measures
Measured here, not assumed.
- Gamut the browser reports
- The color-gamut media query: sRGB, Display P3 or Rec. 2020, the widest that matches. Some browsers report none, which is not a verdict on the screen.
- Wide colour in CSS and canvas
- Whether CSS can name color(display-p3 ...) and color(rec2020 ...) colours, and whether a canvas can be made in the Display P3 colour space.
- Swatches, by eye
- Pairs of red, green, blue and cyan at the edge of sRGB with the same primary at the edge of Display P3 inside, and a Display P3 green around a Rec. 2020 green. On an sRGB path each pair looks like one square.
- HDR and colour depth
- Whether the browser is offered HDR, and the colour depth the system reports, because both change what reaches the page.
If it fails
The usual failures, and what fixes each.
- A wide-gamut screen reads sRGB on Windows
- In Settings, System, Display, look for Automatically manage color for apps under the screen, where your hardware offers it, or turn HDR on. Install the screen's own colour profile from its maker; Chrome and Edge read the gamut from it.
- A wide-gamut screen reads sRGB on a Mac
- System Settings, Displays, Color profile: choose the display's own profile rather than sRGB.
- It reports P3 but the swatches look the same
- Look straight on at full brightness. Check the screen's menu for an sRGB mode, which clamps a wide panel on purpose.
Where a browser stops
What it cannot tell you.
- Coverage percentage, accuracy (delta E), white point and calibration. These need a colorimeter on the screen; this test never prints a percentage.
- Whether a panel that reports sRGB is wide underneath. A wide panel on an sRGB path and an sRGB panel look the same from a web page.
- Your eyes, the room and the angle. The swatch answer is yours.
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
Colour gamut test, answered
- How do I test my monitor's colour gamut?
- Run the test above. It shows which gamut the browser is given and asks whether you can see the wider swatches. For a coverage percentage you need a colorimeter; no web page can measure one.
- Can a website measure DCI-P3 coverage?
- No. A web page can read the gamut the browser is given and show colours, but it cannot measure light from the panel. Sites that print a coverage percentage from a browser are guessing.
- Why does my P3 laptop show sRGB here?
- The system or the browser is not passing the wider gamut through: a colour profile set to sRGB, colour management off, or a browser that does not report it. The fixes above cover each.
- Is this the same as the HDR test?
- No. The HDR test reads whether high dynamic range is on. This reads the colour gamut and adds swatches for the eye. A screen can be wide gamut without HDR.
- Do I need a wide-gamut screen?
- Only for work or play made in a wide gamut: photo editing for print or P3 devices, HDR video and some games. Most web pages and documents are sRGB.
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