A nit is short for candela per square meter (cd/m²) — a measure of how much light a surface actually emits. It's the unit displays are rated in, and the unit HDR transfer functions like PQ are calibrated against directly. When a spec sheet says "1000-nit peak brightness," that's a physical claim, not a vibe.
Some real reference points
- ~0.001 nits — a moonless night sky
- ~1–5 nits — a dim room, most phone screens at night
- 100 nits — the SDR reference white point most images are graded against
- 200–300 nits — typical laptop/monitor brightness indoors
- 400–600 nits — a bright HDR-capable phone or monitor
- 1,000–2,000 nits — a good HDR TV at peak highlight brightness
- 4,000–10,000 nits — the outer edge of what HDR mastering formats can specify (PQ tops out at 10,000)
- ~1.6 billion nits — the sun's surface, for scale, and no display will ever get near it
Why HDR cares so specifically
SDR never needed this precision — everything was implicitly relative to that ~100-nit reference white, and the actual brightness on your specific screen was whatever your brightness slider was set to. HDR's PQ transfer function is different: it's an absolute scale, so a given code value is supposed to mean the same real-world nit value on every compliant display. That's what lets a 1,000-nit highlight look like a genuinely bright highlight rather than just "pretty bright for this screen."
The catch: your screen still has to keep up
A file can specify 4,000 nits; your screen still can only show what it can physically produce. Most displays tone-map anything above their real peak brightness back down. This is normal and expected — it's exactly why our tools distinguish between what a file says and what your specific display can actually show, rather than assuming one implies the other.