luminance converter
Unit Converters
L
=
I
A à cos(θ)
- L (Luminance): Perceived brightness (cd/m² or Nits).
- I (Luminous Intensity): Light power in a direction (cd).
- A (Area): Physical surface area (m²).
- cos(θ): Viewing angle correction factor.
Luminance converter Table
| Unit | cd/m² | cd/cm² | cd/ft² | cd/in² |
|---|---|---|---|---|
| 1 cd/m² | 1 | 0.0001 | 0.0929031299 | 0.00064516 |
| 1 cd/cm² | 10,000 | 1 | 929.0312990645 | 6.4516 |
| 1 cd/ft² | 10.7639 | 0.00107639 | 1 | 0.0069444377 |
| 1 cd/in² | 1,550.0031 | 0.15500031 | 144.0001393547 | 1 |
What is luminance converter?
Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction. It describes the amount of light that passes through, is emitted from, or is reflected off a particular area, and falls within a given solid angle. In simpler terms, while "illuminance" measures how much light hits a surface, Luminance measures how "bright" that surface appears to the human eye. A Luminance Converter is a mathematical tool used to translate these values between various units such as Candelas per square meter (cd/m²), Nits, and Foot-lamberts (fL).
Understanding the Values
The Nit (nt): This is the non-SI name for 1 cd/m². It comes from the Latin nitere, meaning "to shine." It is the standard unit for measuring the brightness of smartphone screens, monitors, and TVs.
Foot-lambert (fL): A unit used primarily in the United States motion picture industry. It represents the luminance of a perfectly reflecting surface receiving one foot-candle of illumination.
The Factor of Ď: In many luminance conversions, the mathematical constant Ď appears. This is because light often reflects off a "Lambertian" surface (like a piece of paper) in a hemispherical pattern, and Ď is required to relate the flat surface area to that curved distribution of light.
History and Origin
A History of "Perceived" Brightness
The history of the luminance converter is a journey from the flickering flame to the high-dynamic-range (HDR) displays of the 21st century.
The Lambertian Foundation
In the 18th century, Johann Heinrich Lambert established the laws of photometry. He realized that a "perfect" surface looks equally bright from any angle because the decrease in apparent area is exactly balanced by the decrease in light intensity. This became known as Lambert's Cosine Law, the very foundation of the luminance formula we use today.
The Cinema Era
In the early 20th century, with the rise of the film industry, engineers needed to standardize how bright a movie screen should be so that audiences wouldn't suffer from eye strain. They developed the Foot-lambert. This allowed a theater in New York and a theater in London to ensure their projectors were calibrated to the same "perceived" brightness, despite using different equipment.
The Digital Revolution
As cathode-ray tube (CRT) televisions were replaced by Liquid Crystal Displays (LCD) and OLEDs, the term Nit became a household word for tech enthusiasts. Manufacturers began using luminance converters to boast about their products; for example, a standard laptop might have 300 nits, while a high-end smartphone can reach 2000 nits to remain visible in direct sunlight.
Today, luminance converters are vital for safety in automotive engineering (ensuring dashboard lights aren't blinding at night) and in architecture (preventing "glare" in office buildings).
Frequently Asked Questions
How accurate is this luminance converter tool?
Our tools utilize high-precision floating point math guaranteeing accuracy up to the 6th decimal place.
Is this free to use?
Yes, all converters and calculators on ToolsMetrics are 100% free with no limits.