Illuminance Converter
Precision lighting calculations for architectural design, photography, and workplace safety standards.
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Common Illuminance Reference
Lux (lx)
The SI derived unit of illuminance. Equal to one lumen per square meter. Standard for most global lighting.
Foot-candle (fc)
US customary unit. One lumen per square foot. Widely used in American photography and architecture.
Phot (ph)
CGS unit of illuminance equal to 10,000 lux. Used in high-intensity lighting scientific contexts.
Nox (nx)
Obsolete unit equal to 1 millilux. Historically used for measuring low-light conditions like moonlight.
Standard Lighting Requirements
| Environment | Lux Requirement | Typical Purpose |
|---|---|---|
| Office Workspace | 300 - 500 lx | Writing, typing, reading documents |
| Detailed Drawing | 750 - 1000 lx | Technical drafting, fine assembly |
| Home Living Room | 100 - 300 lx | Casual reading, relaxation, socializing |
| Warehousing | 100 - 200 lx | Movement of vehicles, storage retrieval |
| Outdoor Parking | 10 - 50 lx | Safety, security, vehicle navigation |
What is Illuminance?
Definition
Illuminance is a measure of the amount of luminous flux incident per unit area. It tells us how bright a surface appears when illuminated by a light source.
Unlike luminance, which measures light emitted from a surface, illuminance focuses on light falling onto a surface and is critical for ensuring environments are adequately lit for human activities.
The Inverse Square Law
The intensity of light radiating from a point source is inversely proportional to the square of the distance from the source. Doubling the distance reduces illuminance to one-quarter.
E = I / d²Where E is illuminance, I is luminous intensity, and d is distance.