What does a display's nits rating actually mean?
Nits measure luminance — how much light a display emits per unit area — and the figure matters most for two things people rarely connect: outdoor readability and HDR.
What the number describes. One nit is one candela per square metre. Higher means brighter. A typical indoor monitor might operate comfortably around a couple of hundred nits; phones and premium televisions reach far higher figures.
Where brightness genuinely matters:
Sunlight readability. This is the most practically relevant use. A screen competing with daylight needs high peak brightness simply to remain legible, which is why phone brightness figures rose sharply and why cheap devices become unusable outdoors.
HDR. High dynamic range content is mastered with specific brightness levels in mind. A display that cannot reach high peak brightness cannot show HDR as intended — it will accept the signal and tone-map it down, which is why HDR frequently looks disappointing or even dimmer than standard content on lower-specification screens. This is the largest single reason for the gap between HDR's reputation and people's experience of it.
Room conditions. A bright room needs a brighter display.
Why quoted figures are hard to compare:
Peak versus sustained. Many displays hit a high figure briefly, on a small portion of the screen, and cannot maintain it. Full-screen sustained brightness is frequently far lower than the headline, and is the more meaningful number.
Window size. Measurements are quoted on a percentage of the screen — a 10% window figure is not comparable with a 100% one.
OLED behaves differently from LCD. OLED produces perfect black by switching pixels off, so its contrast is effectively infinite, and it can look better than a brighter LCD despite lower peak brightness. Contrast frequently matters more than absolute brightness for perceived quality.
Automatic brightness limiting reduces output to manage heat and power, particularly on OLED.
The certification tiers — DisplayHDR and similar — specify minimum brightness levels, and the lowest tiers are widely regarded as too low to deliver a meaningful HDR effect.