Enter your illuminance in lux, choose your area unit, then provide either a surface area or sphere radius to calculate luminous flux in lumens — with your conversion factor and calculated area shown alongside.
Luminous Flux
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Conversion Factor
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Calculated Area
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Lux measures illuminance (light intensity on a surface), while lumens measure luminous flux (total light output from a source). Lux = lumens per square meter.
Multiply lux by the surface area in square meters: Lumens = Lux × Area (m²). For square feet, use the conversion factor 0.09290304.
Use spherical calculation for point light sources like bulbs where light radiates in all directions. The formula uses 4πr² as the surface area of the sphere.
Office work requires 300-500 lux, reading needs 500-750 lux, detailed tasks require 750-1000+ lux, and outdoor daylight ranges from 10,000-100,000 lux.
Lumens represent total light output while lux measures light per unit area. To convert between them, you must know the area over which the light is distributed.
Yes, this calculator helps determine the total lumens needed from LED fixtures to achieve desired lux levels on work surfaces or in rooms.
One square foot equals 0.09290304 square meters. This factor is automatically applied when you select square feet as your area unit.