HDR Explained
The tier on the box is a set of measured requirements. What your browser reports is something else entirely, and this page keeps the two apart.
VESA's DisplayHDR tiers set published minimums. DisplayHDR 400 requires 400 cd/m² peak luminance on an 8% center patch, a 0.4 cd/m² black level, 90% DCI-P3 and a 10-bit video signal; DisplayHDR 600 requires 600 cd/m² and a 0.1 cd/m² black level; DisplayHDR 1000 requires 1000 cd/m², 0.05 cd/m² and 95% DCI-P3; and the True Black tiers keep the same luminance steps with a 0.0005 cd/m² black level. A browser cannot measure any of that — it can only report what your system says is available, which is what the HDR Test shows.
“Is my monitor really HDR?” has two answers, and they are not the same answer. One is about a certification with published, measured requirements. The other is about what your computer and browser currently have switched on. Most confusion about HDR lives in the gap between them.
The tiers, as VESA publishes them
VESA describes DisplayHDR as “the display industry’s first fully open standard specifying HDR quality, including luminance, color gamut, bit depth, and rise time”. These are the figures a display must meet to carry each logo.
| Tier | Peak luminance (8% center patch) | Black level | Color gamut | Bit depth |
|---|---|---|---|---|
| DisplayHDR 400 | 400 cd/m² | 0.4 cd/m² | 90% DCI-P3 | 10-bit video signal |
| DisplayHDR 500 | 500 cd/m² | 0.1 cd/m² | 90% DCI-P3 | 10-bit video signal |
| DisplayHDR 600 | 600 cd/m² | 0.1 cd/m² | 90% DCI-P3 | 10-bit video signal |
| DisplayHDR 1000 | 1000 cd/m² | 0.05 cd/m² | 95% DCI-P3 | 10-bit video signal |
| DisplayHDR 1400 | 1400 cd/m² | 0.02 cd/m² | 95% DCI-P3 | 10-bit video signal |
| True Black 400 to 1400 | the same luminance steps | 0.0005 cd/m² | as above | 10-bit video signal |
Read from VESA's published performance criteria on September 23, 2026.
Two things in that table do most of the work.
The luminance figure is measured on an 8% center patch, not across the whole screen. A small bright area is far easier to drive than a full white field, which is why a display can meet a peak-luminance requirement and still not be blindingly bright in ordinary use.
The black level is where the tiers really separate. From 0.4 down to 0.02 cd/m² across the standard tiers, and 0.0005 cd/m² for True Black. Peak brightness makes highlights pop; black level decides whether the dark half of the picture looks like night or like gray fog.
Two screens can share a number on the box and differ by a factor of hundreds in the part of the picture you actually sit in.
An HDR claim without a tier
VESA is direct about this: only displays that meet all the specifications may carry the DisplayHDR logo, and if a monitor claims HDR support without the DisplayHDR specification, “it’s likely that the product does not meet the certification requirements”.
That does not mean the screen is lying about accepting HDR content. A display can take an HDR signal, decode it correctly and show it — with whatever brightness and black level it happens to have. Accepting the signal and reproducing it well are different abilities, and only the second one is what the tiers measure.
What your browser can tell you
Very little, and the HDR Test is built to be honest about exactly how little.
It asks your browser a few standard questions — whether high dynamic range output is available, whether wide color is available — and shows the answers as they come back. That is all.
A "reported" answer means the mode is available to the browser at that moment. It is not a measurement, not a certification, and not a promise that anything will look good. A screen that reports high dynamic range may be an entry-level panel accepting an HDR signal and showing it with ordinary brightness and contrast.
The answers also depend on things that have nothing to do with the panel: the operating system’s HDR switch, the connection, the browser, and whether the window is on an HDR-capable display at all. Turning HDR on in the system and reloading the page often changes what is reported, which tells you the reporting is about the pipeline, not the glass.
Checking your own setup, in order
- 1
Find the tier, not the word. Look for a DisplayHDR number on the box or the product page. "HDR ready" or "HDR support" on its own is not a tier.
- 2
Turn HDR on in the system, not just in the monitor menu. Both have to agree before anything reaches the screen as HDR.
- 3
Open the HDR Test and reload. The answers describe the pipeline as it is right now, so they change when the system setting does.
- 4
Check the SDR side too. If ordinary windows look washed out once HDR is on, the system's brightness balance for standard content is the setting to look for.
Judging HDR properly
There is no way around content made for it, played in something that supports it, on a display with HDR switched on. What you are looking for is bright highlights that stand out against genuinely dark shadows, without the whole picture looking washed out or the dark half turning gray.
Two checks on this site cover the parts a browser can show honestly. The Screen Contrast Test shows whether near-black steps stay distinguishable, which is the same question the black-level requirement asks. The Color Banding Test shows whether gradients break into steps, which is where a 10-bit signal earns its place.
And if HDR looks worse than SDR on your screen, that is worth knowing too: on a display near the bottom of the tier list, with the system’s HDR brightness setting untouched, it often will.
Questions
Is DisplayHDR 400 real HDR?
It is the lowest published tier, and it is a real certification with measured requirements: 400 cd/m² peak on an 8% center patch, a 0.4 cd/m² black level, 90% DCI-P3 and a 10-bit video signal. Whether that looks like HDR to you is a different question, and the black-level requirement is where it differs most from the higher tiers.
What does True Black change?
The black level. VESA's True Black tiers keep the same peak-luminance steps but require a black level of 0.0005 cd/m², against 0.4 down to 0.02 cd/m² for the standard tiers. That is the figure that decides whether a dark scene looks deep or gray.
My monitor says HDR but has no DisplayHDR logo. What does that mean?
VESA's own position is that if a monitor claims HDR support without the DisplayHDR specification, "it's likely that the product does not meet the certification requirements". It may still accept an HDR signal; it has simply not been tested against a published standard.
Does the HDR Test prove my screen is HDR?
No, and it says so. It reports what your browser answers to a few standard questions. A "reported" answer means the mode is available to the browser right now — not that the panel meets any tier, and not that content will look good.
Why does my screen look washed out with HDR switched on?
Usually because non-HDR content is being shown through an HDR pipeline, or because the system's HDR brightness setting is off. It is a setting problem far more often than a panel problem.
How this guide was made
Every tier requirement is quoted from VESA's own DisplayHDR performance criteria page, with the date it was read, and the statement about uncertified HDR claims is quoted from the DisplayHDR home page. What the browser reports describes ScreenTail's own HDR Test as it is built.
No verdict on which tier is worth buying, and no claim that any tier looks a particular way: brightness, black level and gamut are measured figures, and how they look depends on the room and the content. No measurement of your own screen either, because a browser has no light sensor.
- 01The DisplayHDR tier requirements: peak luminance on an 8% center patch, black level, DCI-P3 coverage and bit depth for 400, 500, 600, 1000 and 1400, and the True Black black-level requirement: VESA, DisplayHDR performance criteria — retrieved Sep 23, 2026.
- 02What the DisplayHDR specification covers, that only displays meeting all specifications may carry the logo, and what an HDR claim without the specification likely means: VESA, DisplayHDR — retrieved Sep 23, 2026.