Enter your Luminous Intensity (in candelas) and Beam Angle, then choose your Calculation Type to find Luminous Flux (in lumens) — or flip it around and enter a known Luminous Flux value to back-calculate Luminous Intensity and Solid Angle.
Luminous Flux
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Luminous Intensity
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Solid Angle
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Luminous flux (lumens) measures the total light output from a source, while luminous intensity (candela) measures how bright the beam appears in a specific direction. Flux considers the entire light emission, intensity focuses on directional brightness.
LED luminous intensity is typically listed in the product datasheet or specifications, usually measured in millicandela (mcd) or candela (cd). Look for values like 'luminous intensity at peak wavelength' or 'axial luminous intensity'.
Beam angle determines how the light is distributed. A narrow beam concentrates light in a smaller solid angle, while a wide beam spreads it over a larger area. The solid angle (calculated from beam angle) is essential for converting between intensity and total flux.
Narrow beams (15-30°) are ideal for spotlights and accent lighting. Medium beams (30-60°) work well for task lighting. Wide beams (60-120°) are perfect for general ambient lighting and area illumination.
This calculator assumes a uniform light distribution within the beam angle, which is accurate for most LEDs and standard light sources. For complex beam patterns or non-uniform distributions, professional photometric testing may be needed.
Yes, this calculator works for any light source where you know the luminous intensity and beam angle - including LEDs, halogen bulbs, fluorescent lights, and other fixtures with defined beam characteristics.