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HDR & Color Depth Checker — Test Your Display Online

Check your display color depth, gamut, and HDR support.

Check your display's colour depth, HDR support, and gradient smoothness.

HDR Support

Checking...

Colour Depth (screen)

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Colour Gamut (estimated)

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8-bit gradient ramp — look for visible steps/banding

Luminance stepped ramp (banding test)

Colour bars — HDR test pattern

Fine greyscale steps (reveals banding)

HDR detection via window.matchMedia('(dynamic-range: high)'). Browser-reported HDR does not guarantee good HDR hardware.

How it works

What is an HDR and colour depth test?

This tool checks your display's ability to render high dynamic range content and smooth colour gradients. It reads your browser's HDR capability flags, estimates colour depth from the Screen API, and displays several gradient patterns designed to reveal colour banding. A display that handles HDR well should show smooth, step-free gradients across all test patterns.

HDR vs SDR — what to look for

Brightness and contrast

HDR content relies on high peak brightness and deep blacks to create a realistic, high-contrast image. A proper HDR display should reach at least 400 nits peak brightness (DisplayHDR 400) with good local dimming. Higher certifications like DisplayHDR 600, 1000, or Dolby Vision indicate more capable hardware. Without sufficient brightness, HDR content can look flat and dimmer than expected.

Colour gamut

HDR uses the DCI-P3 or Rec.2020 colour spaces, which are significantly wider than the sRGB space used by most SDR content. A display that covers 90% or more of DCI-P3 will show noticeably more vibrant reds, greens, and blues in HDR content. Budget HDR monitors often cover only sRGB, defeating the purpose of HDR.

What banding reveals about your display

Colour banding in the gradient test is a clear sign of limited colour depth. If you see distinct horizontal stripes instead of a smooth fade, your display is likely operating in 8-bit mode. Some displays use FRC (Frame Rate Control) to simulate 10-bit — these may show faint dithering noise instead of hard bands. True 10-bit panels should display a nearly perfect gradient. Banding is also more visible at lower brightness levels and on VA panels compared to IPS or OLED.

Limitations of browser-based HDR testing

This test relies on the browser's reported capabilities via the CSS Media Queries Level 5 specification. A "yes" for HDR support means the OS and display driver have HDR enabled, but it does not measure peak brightness, colour gamut coverage, or local dimming quality. For accurate HDR assessment, use dedicated calibration tools like DisplayCAL or an HDR calibration pattern from a known source. Additionally, screen-reported colour depth via the Screen API is unreliable on many browsers and may always report 24-bit (8-bit per channel) even on 10-bit panels.

Related tools

Frequently Asked Questions

What is the difference between HDR and SDR? expand_more
Standard Dynamic Range (SDR) uses a limited brightness range (typically up to 100–300 nits) and a standard colour space (sRGB/Rec.709). High Dynamic Range (HDR) extends brightness up to 400–10,000 nits and uses wider colour spaces like DCI-P3 or Rec.2020, producing more vibrant colours, brighter highlights, and deeper blacks. HDR also uses 10-bit colour depth to avoid banding in smooth gradients.
Why does the browser say HDR is supported but the test looks the same? expand_more
The browser reporting HDR support via matchMedia means the OS and display are configured for HDR output. However, many factors affect actual HDR quality: peak brightness, colour gamut coverage, local dimming quality, and proper HDR calibration. A display can correctly report HDR support but deliver a poor HDR experience if it lacks the hardware capability.
What is colour banding and what causes it? expand_more
Colour banding appears as visible steps or stripes in smooth gradients instead of a seamless transition. It happens when there are not enough colour values to represent the gradient smoothly. 8-bit panels display 256 levels per channel (16.7 million colours), which can show banding in subtle gradients. 10-bit panels show 1,024 levels per channel (1.07 billion colours), producing much smoother gradients.
How can I tell if my display is truly 10-bit? expand_more
Many monitors advertise "8-bit + FRC" (Frame Rate Control) which simulates 10-bit by rapidly flickering between two nearby shades. True 10-bit panels are less common and more expensive. The gradient tests on this page can help: an 8-bit panel will show visible banding in the smooth ramp, while a true 10-bit panel should show a nearly seamless transition. Some browsers can report colour depth via the Screen API, but the reported value may be inaccurate.
Does HDR work in all browsers? expand_more
HDR support varies by browser and OS. As of 2025, Safari on macOS has the most mature HDR implementation, properly sending HDR metadata to the display. Chrome and Edge support HDR on Windows and ChromeOS. Firefox has limited HDR support. For accurate HDR testing, use the latest version of Safari on a Mac or Chrome on Windows with HDR enabled in display settings.