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💡 Luminance & Light Measurement Converter

Advanced photometry tools, natural lighting reference data, and interactive learning

Display & Surface Brightness

400 nit = 400 cd/m²
Smartphone screen (typical)
1000 nit = 1000 cd/m²
HDR TV peak brightness
100 cd/m² = 29.2 fL
Computer monitor
10,000 nit = 10,000 cd/m²
HDR reference monitor

Lighting Conditions

100,000 lux = 9,290 fc
Direct sunlight
10,000 lux = 929 fc
Overcast day
500 lux = 46.5 fc
Office lighting
0.25 lux = 250 mlux
Full moon

🔬 Photometry & Vision Science

Human Visual System & Photometry

Photometry measures light as perceived by the human eye, weighted by the luminous efficiency function V(λ). This differs from radiometry, which measures all electromagnetic radiation regardless of human perception.

Φᵥ = Km ∫ Φₑ(λ) × V(λ) dλ

Where Km = 683 lm/W is the maximum luminous efficacy at 555nm (peak human sensitivity).

Interactive Brightness Demonstration

Click buttons to see different brightness levels

Experience the logarithmic nature of human vision perception

🌈 Color Temperature & Light Quality

Light sources emit different color temperatures measured in Kelvin (K), affecting mood, circadian rhythms, and visual perception.

2700K
Warm Incandescent
3000K
Halogen
4000K
Fluorescent
5000K
Daylight
6500K
Cloudy Sky
9000K
Blue Sky

📚 History of Light Measurement

1860
Standard Candle First attempts at standardizing light measurement
1884
Hefner Lamp German standard for luminous intensity
1948
Modern Candela Defined based on blackbody radiation
1979
Current Definition Candela redefined using monochromatic radiation
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Display Technology

HDR, OLED, brightness standards

📸
Photography

Exposure, metering, lighting

🏢
Architecture

Daylighting, energy efficiency

🔬
Research

Vision science, circadian studies

🚗
Automotive

Headlights, HUD, safety

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Agriculture

LED grow lights, plant biology

❓ Frequently Asked Questions

What is luminance?
Luminance measures the brightness of a surface as perceived by the human eye, expressed in cd/m² or nits. It's different from illuminance, which measures light falling on a surface.
How is photographic exposure calculated?
Exposure is controlled by three factors: aperture (f-stop), shutter speed, and ISO. The exposure value (EV) formula is EV = log₂(N²/t) where N is f-number and t is shutter speed in seconds.
What does color temperature mean for lighting?
Color temperature describes the warmth or coolness of light, measured in Kelvin. Lower values (2700K) appear warm/yellow, while higher values (6500K) appear cool/blue. It affects mood and circadian rhythms.
How bright are typical displays in nits?
Display brightness is measured in nits (cd/m²). Typical smartphones: 400-800 nits, HDR TVs: 1000+ nits, professional monitors: 4000+ nits. Higher brightness improves visibility in bright environments.
How much light do different activities need?
Lighting standards specify minimum illuminance levels for different activities:
  • Reading: 500 lux
  • Office work: 300-500 lux
  • Detailed tasks: 750-1000 lux
  • Surgery: 50,000 lux

📊 Quick Reference

Key Constants
Km = 683 lm/W
1 cd = 1 lm/sr
1 fc = 10.764 lux
Common Conversions
1 nit = 1 cd/m²
1 fL = 3.426 cd/m²
1 sb = 10⁴ cd/m²
Typical Levels
Moonlight: 0.25 lux
Office: 500 lux
Sunlight: 100,000 lux

📷 Exposure Calculator

Camera Settings

🏢 Lighting Standards

Reading 500 lux
Office Work 300-500 lux
Retail 750 lux
Surgery 50,000 lux
Photography 1000+ lux
Sports Arena 1500 lux

🌡️ Color Temperature

Candle 1900K
Incandescent 2700K
Fluorescent 4000K
Daylight 5600K
Sky 10000K

☀️ Typical Lighting Levels

Reference illuminance values for common natural and artificial lighting conditions

32,000–100,000 lux
Direct Sunlight (~5,500K)
1,000–10,000 lux
Overcast Daylight (~6,500K)
300–500 lux
Office Lighting
0.1–0.3 lux
Full Moon

Approximate values • Actual levels vary with latitude, season, weather and time of day