Luminance Converter

Same value in every unit

UnitValue

Nits and candela per square metre are the same thing

There is no conversion between them: one nit is one candela per square metre. The word "nit" survives because it is shorter, and display marketing prefers it. Standards documents use cd/m².

Screen brightness in practice

  • 250–350 nits — an ordinary laptop, fine indoors
  • 400–600 nits — comfortable in a bright room
  • 1000+ nits — readable in direct sunlight, and typical of HDR peaks
  • 48 cd/m² (14 fL) — cinema screen white, far dimmer than any phone

Luminance is not illuminance

Lux measures light arriving on a surface. Nits measure light leaving one. A desk lit to 500 lux and a monitor emitting 500 nits are describing different things, and no factor converts between them without knowing how the surface reflects.

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Frequently Asked Questions

What is a nit?

Another name for one candela per square metre. They are the same unit — screen manufacturers say nits, standards documents say cd/m². When a phone is advertised at 1000 nits, that is 1000 cd/m².

How many nits do I need?

Around 250 to 350 for a laptop indoors, 400 to 600 to be comfortable near a window, and 1000 or more to stay readable in direct sunlight. HDR content is mastered against much higher peaks, often 1000 or 4000 nits.

What is the difference between luminance and illuminance?

Illuminance, in lux, is light landing on a surface. Luminance, in nits, is light coming off one — which is why screens are rated in nits and rooms in lux. They are not interchangeable.

Why do projector people use foot-lamberts?

Because it is the customary unit for projected images in the United States. Cinema standards specify around 14 fL for a film print white, which is roughly 48 cd/m² — far dimmer than any phone screen.

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