Peak Nits and the Conditions That Produce Them

The Number Is Always Conditional

Peak luminance is measured on a small white window — typically 10 % of screen area, sometimes 2 % — against a black surround. That window size matters because self-emissive panels (OLED, microLED) draw power proportional to how many pixels are lit, and LCD backlights have finite thermal limits. At 2 % APL (average picture level), the panel can dump most of its power budget into a tiny patch of screen. At 100 % APL — a full white field — that same panel might sustain only a fifth of the headline figure. The spec sheet quotes the first condition and buries the second.

The distinction between burst brightness and sustained brightness follows directly. Burst peak is measured over a few seconds before thermal throttling intervenes; sustained peak is what the panel actually holds after the display's thermal management kicks in — typically thirty to ninety seconds of continuous stimulus. On many LCD panels the gap between burst and sustained is modest. On some OLED panels it is dramatic: a display that briefly touches 1,500 nits at 10 % APL may sustain 700 nits at the same window size after two minutes. Neither figure is dishonest in isolation; quoting only the former is.

Window size conventions are not standardised across manufacturers. One brand measures at 10 %, another at 2 %, and marketing copy rarely discloses which. A useful cross-check is to find the full-field white measurement — the number that reflects typical rather than peak brightness — and treat the ratio between that and the headline peak as a rough indicator of how aggressively the panel is being pushed into burst mode.

Real HDR content rarely lives at a single APL. A specular highlight occupies a few pixels; an overcast sky fills the frame. A panel that compresses aggressively above 50 % APL will clip midtone-adjacent highlights in exactly the scenes that matter most. The peak nit figure tells you the ceiling; the APL curve tells you where the walls are.