HDR Test.
Check the live capability panel first, then compare the wide-gamut swatches and full-screen patterns to see whether HDR is genuinely active on your display.
Wide gamut: P3 vs sRGB
Each swatch is split: the left half is the standard sRGB colour, the right half is the same colour in Display P3. On a wide-gamut HDR panel the P3 half is visibly richer — most in the reds and greens. If both halves look identical, your display (or the browser pipeline) is limited to sRGB.
This is the one part of an HDR check a browser does truthfully: P3 colours only render wider on a panel that can actually show them.
HDR tiers & formats
What the certification numbers mean, and the formats that carry HDR. Peak brightness and local dimming separate real HDR from the "HDR compatible" badge.
| Tier | Peak | What to expect |
|---|---|---|
| HDR 400 | 400 nits | Entry — often no local dimming; marginal HDR |
| HDR 600 | 600 nits | Good — some local dimming, real highlights |
| HDR 1000 | 1000 nits | Premium — full-array dimming, punchy HDR |
| HDR 1400+ | 1400 nits+ | Elite — mini-LED / pro mastering |
| True Black 400/500 | 400–500 nits | OLED — perfect blacks, lower peak |
HDR10
Baseline, static metadata, 10-bit — universal
HDR10+
Dynamic metadata, scene-by-scene tone mapping
Dolby Vision
Dynamic metadata, up to 12-bit — licensed
HLG
Broadcast HDR, no metadata — live TV
How to check HDR on your display
HDR is a whole pipeline — panel, cable, GPU, OS setting and app all have to agree. This test checks the parts a browser can actually see and gives you patterns to judge the rest by eye.
- 1. Turn HDR on first. Enable it in Windows ("Use HDR") or macOS ("High Dynamic Range") — otherwise the browser reports SDR no matter what the panel can do.
- 2. Read the capability panel. Dynamic range "high" plus a P3 or Rec.2020 gamut means the pipeline is HDR-ready.
- 3. Check the wide-gamut swatches. The P3 halves should look richer than sRGB. Identical halves mean an sRGB-only panel or pipeline.
- 4. Run the patterns. Use black & white and the highlight ladder to judge local contrast and how many near-white steps stay distinct — then confirm real HDR with actual HDR video.
What your results mean
Read the live capability panel together with the wide-gamut swatches and patterns to tell genuine HDR from a pipeline that only claims it.
| What you see | What it means | What to do |
|---|---|---|
| Dynamic range reads "High (HDR)", gamut reads P3 or Rec.2020, and the P3 half of each swatch looks clearly richer than the sRGB half | Your panel, OS and browser are all in a genuine HDR / wide-gamut pipeline | Nothing to do — pair this with real HDR video content to judge true peak brightness. |
| Dynamic range reads "Standard (SDR)" | HDR isn't engaged anywhere in the pipeline — panel, OS or browser | Turn on HDR in Windows ("Use HDR") or macOS ("High Dynamic Range") and confirm the cable and GPU output support it. |
| Dynamic range reads "High", but every swatch's P3 and sRGB halves look identical | The pipeline is flagged HDR, but the panel (or its colour management) is capped at sRGB, so the wider P3 colour is clipped down to it | A panel gamut limit — no software setting adds colour a display isn't built to show. |
| Colour depth reads 24-bit (8 bits per channel) | Your output isn't in the 10-bit mode HDR content is mastered for, so gradients band more easily | Look for a 10-bit / 12-bit output option in the GPU driver, and check our colour depth test. |
| The highlight ladder's brightest two or three steps near white look identical | Highlights are clipping — detail near white is lost, from either the panel's peak brightness or a picture mode | Turn off any "vivid" or dynamic-contrast picture mode and re-check; if it's still flat at neutral settings, that's the panel's peak-brightness limit. |
Frequently asked questions
Can a browser really test HDR?
Partly, and this test is honest about which parts. It can reliably detect your display's HDR capability (dynamic-range, colour gamut and bit depth via the browser's media queries) and it can show genuine wide-gamut P3 colours that only render on a P3/HDR panel. What it cannot do is drive true peak-brightness HDR — a plain CSS white is SDR white, not a 1000-nit highlight. For that you need real HDR video content and, to measure peak nits, a colorimeter.
How do I know if HDR is actually working on my display?
Check the "Your display" panel: if dynamic range reads "high" and the gamut is P3 or Rec.2020, your browser is in an HDR-capable pipeline. Then open the wide-gamut swatches — on a working HDR/P3 panel the P3 half of each pair looks clearly more saturated than the sRGB half. If dynamic range reads "standard", HDR is off: enable it in your OS display settings (Windows "Use HDR", macOS "High Dynamic Range") and make sure the cable and GPU support it.
Why do the P3 and sRGB halves look identical?
Two reasons. Either your display only covers sRGB, so it clips the wider P3 colours down to the same values — common on budget panels — or your browser/OS is not in a wide-gamut mode. Confirm the gamut readout says P3 or Rec.2020; if it says sRGB, the panel or the pipeline is the limit. On a true wide-gamut screen the P3 halves are noticeably richer, especially red and green.
What do the DisplayHDR numbers (400, 600, 1000) mean?
They are VESA DisplayHDR tiers, set mainly by peak brightness in nits and whether the panel has local dimming. HDR 400 is entry-level and often barely better than SDR; HDR 600 and up start to deliver real highlights; HDR 1000 and 1400 are premium full-array or mini-LED. OLED panels carry "True Black" tiers instead — lower peak nits but perfect blacks for infinite contrast. The reference table on this page lists them.
HDR looks washed out or too dark — why?
Usually a pipeline mismatch, not the panel. On Windows, HDR can wash out SDR content if the SDR brightness slider is set wrong; on any system, viewing HDR content in a non-HDR app, or SDR content in forced-HDR mode, looks flat. Make sure HDR is switched on only when you have HDR content, calibrate the OS HDR settings, and use an app that supports HDR playback.