Luminous Intensity Converter

Our Luminous Intensity Converter is a comprehensive tool that helps you convert between different units of light measurement: candela (cd), lumen (lm), and lux (lx). Whether you’re working on lighting design, photography, or architectural projects, this calculator makes light measurement conversion simple and accurate.

Understanding Light Measurement Units

Base Unit

Candela (cd)

The candela is the SI base unit of luminous intensity. One candela is defined as the luminous intensity of a source that emits monochromatic radiation of frequency 540×10¹² Hz and has a radiant intensity in that direction of 1/683 watt per steradian.

Derived Units

Lumen (lm)

The lumen is the SI derived unit of luminous flux, a measure of the total amount of visible light emitted by a source. One lumen is equal to the luminous flux emitted into one steradian by a source of one candela.

Lux (lx)

The lux is the SI derived unit of illuminance, measuring luminous flux per unit area. One lux is equal to one lumen per square meter. It’s used to measure how much light is falling on a surface.

Conversion Formulas

Here are the key conversion relationships between different light measurement units:

Candela to Other Units

• 1 candela = 12.57 lumens (in a full sphere)
• Lux depends on distance and beam angle

Lumen to Other Units

• 1 lumen = 0.0795 candela (point source)
• 1 lumen = 1 lux over 1 square meter

Lux to Other Units

• 1 lux = 1 lumen per square meter
• Candela depends on distance and beam angle

Common Light Measurement References

Here are some common light measurement references:

• Standard candle: ~1 candela
• LED bulb (60W equivalent): ~800 lumens
• Full daylight: 10,000-25,000 lux
• Office lighting: 300-500 lux
• Full moon: ~0.1 lux
• Modern LED flashlight: 50-100 candela

How to Use the Calculator

1. Enter a value in any of the input fields
2. The calculator will automatically convert and display the equivalent values in other units
3. Use the Reset button to clear all fields and start a new conversion
4. Hover over the input fields for helpful tooltips

Applications

Light measurement conversion is essential in many fields:

• Lighting Design: Planning indoor and outdoor illumination
• Photography: Determining proper exposure settings
• Architecture: Designing natural and artificial lighting
• Stage Lighting: Creating theatrical lighting effects
• Safety Standards: Meeting workplace illumination requirements
• Horticulture: Managing plant growth lighting

Tips for Accurate Conversion

1. Always double-check critical measurements
2. Use decimal points for precise measurements
3. Consider rounding to appropriate precision for your application
4. Be aware of significant figures in your measurements

Technical Notes

This calculator provides conversions accurate to three decimal places, which is sufficient for most practical purposes. For extremely precise measurements or scientific applications, please use specialized measuring equipment and conversion tools.

The calculator uses standard conversion factors based on point source assumptions. For real-world applications, consider factors such as:

• Distance from light source
• Beam angle and distribution
• Surface reflectivity
• Atmospheric conditions
• Light source characteristics

Note that the relationship between these units can be complex in real-world scenarios, as they measure different aspects of light (intensity, flux, and illuminance). The conversions provided assume ideal conditions and point sources.