Luminous Flux Converter
Convert between lumens, candelas, lux and other light measurement units
Luminous Flux Converter
Conversion Formula:
1 lumen = 0.07958 candela (assuming uniform distribution)
Note: Converting between different types of light measurements (flux to intensity) involves assumptions about light distribution and area.
Equivalent Light Source:
A 75W incandescent bulb (1100 lumens)
Common Light Sources
Understanding Light Measurement Units
Luminous Flux Units:
- Lumen (lm): The SI unit of luminous flux, measuring total visible light in all directions.
- Kilolumen (klm): 1,000 lumens, used for bright light sources.
Luminous Intensity Units:
- Candela (cd): Unit for light intensity in a specific direction.
- Millicandela (mcd): 1/1000 of a candela, common for small LEDs.
Illuminance Units:
- Lux (lx): Light falling on a surface (1 lumen per square meter).
- Foot-candle (fc): Imperial unit (1 lumen per square foot).
- Phot (ph): CGS unit (1 lumen per square centimeter).
Other Units:
- Watt (light): Power equivalent, varies by wavelength.
- Lumen/watt: Measure of lighting efficiency.
Important Relationships:
- • Lumen to Candela: 1 cd = 1 lm / solid angle (sr). For omnidirectional sources: 1 cd ≈ 12.57 lm
- • Lumen to Lux: 1 lx = 1 lm / area (m²). Conversion depends on area and light distribution
- • Lumen to Watt: At 555 nm wavelength (peak eye sensitivity): 1 W = 683 lm
- • Lux to Foot-candle: 1 fc = 10.764 lx
Light Output Reference Chart
| Light Source | Lumens (lm) | Application |
|---|---|---|
| Candle | 10-15 | Decorative lighting |
| Small LED flashlight | 50-100 | Basic portable lighting |
| 40W equivalent LED bulb | 450-500 | Accent household lighting |
| 60W equivalent LED bulb | 800-900 | Standard household lighting |
| 100W equivalent LED bulb | 1500-1600 | Bright household lighting |
| Car headlight (low beam) | 1000-2000 | Vehicle lighting |
| Car headlight (high beam) | 3000-5000 | Long-distance vehicle lighting |
| Basic projector | 2000-3000 | Home theater, presentations |
| Street light | 15000-25000 | Roadway lighting |
| Stadium floodlight | 50000-100000 | Sports and event lighting |
Light Source Efficiency (Lumens per Watt)
Traditional Sources:
- • Incandescent: 10-17 lm/W
- • Halogen: 16-24 lm/W
- • Compact Fluorescent (CFL): 50-70 lm/W
- • Fluorescent tube: 60-100 lm/W
- • Metal Halide: 70-115 lm/W
Modern Sources:
- • LED (consumer): 80-120 lm/W
- • LED (professional): 120-200 lm/W
- • High-pressure sodium: 80-140 lm/W
- • Low-pressure sodium: 100-200 lm/W
- • Theoretical maximum: 683 lm/W (monochromatic at 555 nm)
Higher lumens per watt indicate more energy-efficient lighting. Modern LEDs are 5-10 times more efficient than traditional incandescent bulbs.
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Light Output Visualization
1.0k lumens
Bright light
Light Output Scale
Common Light Sources
Light Measurement Concepts
Luminous Flux (Lumens)
Total amount of visible light emitted by a source in all directions.
Luminous Intensity (Candela)
Luminous flux per solid angle in a particular direction.
Illuminance (Lux, Foot-candle)
Amount of light falling on a surface. Depends on distance from source and beam spread.
Luminous Efficacy (lm/W)
How efficiently a light source converts power to visible light.
Lighting Selection Guide
Recommended lumen levels by room:
Kitchen:
3,000-4,000 lumens total (75-100 lumens/sq ft)
Living Room:
1,500-3,000 lumens total (20-40 lumens/sq ft)
Bedroom:
1,000-2,000 lumens total (10-30 lumens/sq ft)
Bathroom:
4,000-5,000 lumens total (70-100 lumens/sq ft)
Office/Study:
3,000-4,000 lumens total (50-75 lumens/sq ft)
Hallway/Stairs:
500-1,000 lumens total (5-10 lumens/sq ft)
Mobile tip: Swipe left or right on the unit dropdown to quickly change units, or use the arrow buttons
About the Luminous Flux Converter
Convert between lumens, candelas, lux and other light measurement units All conversions run instantly in your browser and nothing you enter is sent to a server.
Common Conversion Formulas
| From | To | Formula |
|---|---|---|
| Lumens (lm) | Candelas (cd), Solid Angle (sr) | lm = cd × sr |
| Illuminance (lux) | Luminous Flux (lm), Area (m²) | lux = lm / m² |
| Luminous Efficacy | Luminous Flux (lm), Power (W) | Efficacy (lm/W) = lm / W |
| Luminance (cd/m²) | Luminous Intensity (cd), Area (m²) | Luminance = cd / m² |