Illumination Converter
Convert between different illumination units including lux, foot-candle, phot, nox, and flame.
Result
1 lx = 10.7639104167 fc
Understanding Illumination Units: Lux to Foot-Candle to Phot
Illumination converters are essential tools for calculating illuminance, light level, and lighting measurements in lighting design, architecture, and photometry. Whether you're working with lux (lx), lumen per square meter (lm/m²), meter-candle, foot-candle (fc), phot (ph), nox, flame, centimeter-candle, candela steradian per square meter, watt per square centimeter steradian at 555 nm, or any of twelve illumination units, understanding illumination conversions is crucial for engineers, designers, and analysts in lighting design, architecture, display technology, automotive lighting, and photometric measurement industries.
Illumination measurements quantify the luminous flux per unit area incident on a surface, representing light level essential for lighting design, visual comfort assessment, and photometric calculations. From low-illumination levels like moonlit scenes at 0.1-1 lux to high-illumination levels like bright sunlight at 100,000+ lux, and from indoor lighting at 100-1000 lux to outdoor lighting at 10,000-100,000 lux, this comprehensive converter supports twelve illumination units with instant, accurate results for all your illuminance, light level, and lighting measurement calculations across different measurement systems.
How to Convert Illumination Units: Formulas and Methods
Lux to Lumen per Square Meter and Meter-Candle Conversions
Converting from lux (lx) to lumen per square meter (lm/m²) is exact, since 1 lux equals 1 lumen per square meter by definition in the SI system. For example, an illumination of 500 lux equals 500 lm/m². Converting to meter-candle (m·c) is also exact, since 1 meter-candle equals 1 lux by definition. These conversions are exact and commonly used in modern photometry and lighting design.
Foot-Candle and Lumen per Square Foot Conversions
Converting from lux to foot-candle (fc) multiplies by approximately 0.093, since 1 foot-candle equals 1 lumen per square foot, and 1 square foot equals 0.09290304 square meters, giving 1 foot-candle = 0.09290304 lux. For example, 100 lux equals approximately 9.29 foot-candles. Converting to lumen per square foot (lm/ft²) uses the same factor, since 1 foot-candle equals 1 lumen per square foot. Foot-candles are commonly used in US lighting design and architecture.
Phot and Centimeter-Candle Conversions
Converting from lux to phot (ph) divides by 10,000, since 1 phot equals 1 lumen per square centimeter, and 1 square centimeter equals 0.0001 square meters, giving 1 phot = 10,000 lux. For example, 10,000 lux equals 1 phot. Converting to centimeter-candle (cm·c) uses the same factor, since 1 centimeter-candle equals 1 phot. Phot units are commonly used in CGS system photometry and older scientific literature.
Flame and Nox Conversions
Converting from lux to flame divides by 107.64, since 1 flame equals 10 foot-candles, and 1 foot-candle equals 10.764 lux, giving 1 flame = 107.64 lux. For example, 1076.4 lux equals 10 flames. Converting to nox multiplies by 1000, since 1 nox equals 0.001 lux (used for very low illumination measurements). Flame units are commonly used in British lighting specifications, while nox is used for extremely low light level measurements.
Illumination Versus Luminance and Luminous Intensity
Illumination (E, lux) measures luminous flux per unit area incident on a surface, while luminance (L, cd/m²) measures luminous intensity per unit area emitted by a surface. Luminous intensity (I, cd) measures light output per unit solid angle. For point sources, E = I/r², where r is distance. Converting illumination units helps engineers calculate light levels, predict visual comfort, and design lighting systems when working with different measurement systems and comparing international photometric standards.
Illumination Conversion Reference Table
| lux | foot-candle | phot | nox | flame |
|---|---|---|---|---|
| 0.1 | 0.009 | 0.00001 | 100 | 0.001 |
| 1 | 0.093 | 0.0001 | 1000 | 0.009 |
| 10 | 0.93 | 0.001 | 10000 | 0.093 |
| 100 | 9.29 | 0.01 | 100000 | 0.93 |
| 500 | 46.5 | 0.05 | 500000 | 4.65 |
| 1000 | 92.9 | 0.1 | 1000000 | 9.29 |
Typical Illumination Values by Application
| Application | lux | foot-candle | Description |
|---|---|---|---|
| Moonlight | 0.1-1 | 0.01-0.09 | Natural night lighting |
| Residential living room | 100-300 | 9-28 | General indoor lighting |
| Office workspace | 300-500 | 28-46 | Task lighting |
| Retail store | 500-1000 | 46-93 | Display lighting |
| Operating room | 5000-10000 | 465-930 | Medical procedure lighting |
| Overcast sky | 1000-2000 | 93-186 | Outdoor daylight |
| Full daylight (shade) | 10000-25000 | 930-2325 | Outdoor daylight |
| Full sunlight | 32000-100000 | 3000-9300 | Direct sunlight |
Industry Applications and Use Cases
Lighting Design and Architecture
Lighting designers use illumination measurements in lux or foot-candles to design lighting systems, optimize visual comfort, and ensure adequate illumination in architectural and interior design. Typical illumination levels range from 100-10,000 lux for various indoor and outdoor applications. Converting between lux, foot-candles, phot, and other illumination units helps designers work with international lighting standards, compare specifications, and design lighting systems when working with different measurement systems and equipment specifications.
Display Technology and Visual Comfort
Display engineers calculate illumination levels in lux to optimize screen visibility, assess visual comfort, and ensure appropriate ambient lighting for displays. Typical ambient illumination levels range from 100-1000 lux for various display applications. Converting between illumination units helps engineers work with international display standards, compare specifications, and design display systems when developing new display technologies.
Automotive Lighting and Safety
Automotive engineers use illumination measurements in lux to design headlights, assess road visibility, and ensure safety in vehicle lighting. Typical road illumination levels range from 1-50 lux for various road conditions. Converting between illumination units helps engineers work with international automotive lighting standards, compare specifications, and design lighting systems when developing new vehicle lighting technologies.
Photography and Cinematography
Photographers and cinematographers use illumination measurements in lux or foot-candles to set exposure, control lighting ratios, and achieve desired image quality. Typical scene illumination levels range from 1-100,000 lux for various photography and cinematography applications. Converting between illumination units helps professionals work with different lighting equipment, compare measurements, and achieve consistent results across different shooting conditions.
Frequently Asked Questions
What is illumination and how is it different from luminance?
Illumination (E, lux) measures luminous flux per unit area incident on a surface, while luminance (L, cd/m²) measures luminous intensity per unit area emitted by a surface. Illumination describes light falling on a surface, while luminance describes light emitted or reflected by a surface. Converting illumination units helps engineers quantify light levels and compare measurements when designing lighting systems.
How do I convert lux to foot-candle?
Multiply lux by 0.093 to get foot-candle (fc), since 1 foot-candle equals 1 lumen per square foot, and 1 square foot equals 0.09290304 square meters, giving 1 foot-candle = 0.09290304 lux. For example, 100 lux equals approximately 9.29 foot-candles. Foot-candles are commonly used in US lighting design and architecture.
How to convert lux to phot?
Divide lux by 10,000 to get phot (ph), since 1 phot equals 1 lumen per square centimeter, and 1 square centimeter equals 0.0001 square meters, giving 1 phot = 10,000 lux. For example, 10,000 lux equals 1 phot. Phot units are commonly used in CGS system photometry.
How to convert foot-candle to lux?
Multiply foot-candle (fc) by 10.764 to get lux, since 1 foot-candle equals 0.09290304 lux, giving 1 lux = 1/0.09290304 = 10.764 foot-candles. For example, 10 foot-candles equals approximately 107.64 lux. This conversion is commonly used in lighting design.
What's the relationship between illumination and luminous intensity?
Illumination (E, lux) measures luminous flux per unit area incident on a surface, while luminous intensity (I, cd) measures light output per unit solid angle. For point sources, E = I/r², where r is distance. Converting illumination units helps engineers calculate light levels and design lighting systems when working with different measurement systems.
How to convert lux to lumen per square meter?
lux equals lm/m² exactly, since 1 lux equals 1 lumen per square meter by definition in the SI system. For example, 100 lux equals 100 lm/m². This conversion is exact and commonly used in modern photometry and lighting design.
How is illumination measured in practice?
Illumination is measured using light meters or lux meters that detect light intensity through sensors with filters matching the human eye's spectral sensitivity. Measurements are performed at the surface where illumination is desired, and illumination is calculated from sensor readings. Converting illumination units helps engineers interpret measurements and compare data across different measurement instruments and international standards.
How to convert nox to lux?
Multiply nox by 0.001 to get lux, since 1 nox equals 0.001 lux. For example, 1000 nox equals 1 lux. Nox is used for very low illumination measurements, such as starlight or extremely dim lighting conditions.
How accurate are illumination conversions?
Our converter uses exact mathematical relationships with 10-decimal precision for SI units. lux to lm/m²: exact 1:1 conversion. lux to foot-candle: multiply by 0.093 (using 0.09290304 factor). lux to phot: divide by 10,000 exactly. These conversions ensure precision for scientific and engineering applications in photometry and lighting design.
How does illumination relate to visual comfort?
Appropriate illumination levels are essential for visual comfort, task performance, and safety. Insufficient illumination causes eye strain and reduces visibility, while excessive illumination can cause glare and discomfort. Recommended illumination levels range from 100-1000 lux for general indoor activities, with higher levels for detailed tasks. Converting illumination units helps engineers assess visual comfort and design appropriate lighting systems when working with different measurement systems.
How to convert flame to lux?
Multiply flame by 107.64 to get lux, since 1 flame equals 10 foot-candles, and 1 foot-candle equals 10.764 lux, giving 1 flame = 107.64 lux. For example, 1 flame equals 107.64 lux. Flame units are commonly used in British lighting specifications.
How is the lux defined in the SI system?
The lux is defined as one lumen per square meter (lx = lm/m²) in the SI system. This definition links illumination to luminous flux through unit area, representing the amount of light falling on a surface. Converting illumination units helps engineers work with the SI system and compare measurements across different photometric standards.
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