Peak brightness is the maximum luminance a display can output, measured in nits (cd/m²). Higher peak brightness improves HDR impact and outdoor visibility.
One nit equals one candela per square meter. Reference points: phone outdoor visibility 800+ nits, premium LCD 600 nits, premium OLED phone 2000+ nits peak (small area), HDR cinema mastering 1000–4000 nits.
Note distinction between full-screen brightness (sustained on entire panel) and peak brightness (small area, brief flash for HDR highlights). Manufacturers often quote peak figures, which are higher.
For smartphones, 1000 nits is the practical sunlight-readable threshold. Flagship phones now reach 2500–3500 peak. For TVs, 1000 nits is the minimum for credible HDR.