A nit is a unit of brightness (candela per square meter, cd/m²). Higher nits mean a brighter screen, improving outdoor visibility and HDR impact.
Nits scale and context: 0 nits: complete darkness. 100 nits: indoor office lighting, dim for outdoor. 300 nits: typical indoor brightness, borderline outdoor visibility. 600 nits: good outdoor visibility in partial sun (office LCD standard). 1000 nits: excellent outdoor visibility (flagship phone standard for peak/small-area). 2000 nits: exceptional brightness (flagship OLED peaks). 3000–4000 nits: cinema/commercial display (mastering grade), not consumer TV brightness.
Distinction: peak vs full-screen brightness. Peak: maximum brightness in a small area (10% of screen, brief flash). Manufacturers quote this (2500 nits peak on iPhone 15 Pro). Full-screen: sustained brightness across entire display. Much lower (~900 nits on same iPhone).
Why it matters: Outdoor readability: 1000 nits peak is the practical threshold for sunlight reading. 600 nits full-screen usually sufficient indoors + partial sun. HDR impact: higher peak brightness shows brighter highlights (sunset, explosions), improving contrast perception. Battery drain: brightness is the largest power consumer on phones and displays. Excessive brightness shortens battery life.
Standard mastery: SDR (Standard Dynamic Range): typically 100 nits peak (phone apps, web). HDR (High Dynamic Range): 1000 nits peak (cinema mastering), practical TV/phone HDR 1000–4000 nits.
When to prioritize: outdoor phone use or watching HDR content (Dolby Vision, HDR10) — higher nits improve visibility and visual pop. For indoor web browsing, anything 300+ nits is fine.