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Lighting Calculator
Professional Tool
Lighting Calculator
Calculate the number of luminaires required based on room dimensions, reflection coefficients, and lighting parameters.
Room Parameters
Enter dimensions and surface properties below
25 m²
total floor area
Room dimensions
Length
m
Width
m
Ceiling height
m
Reflection coefficients
Ceiling color
Wall color
Floor color
Lighting parameters
Illuminance
lx
Working surface
0 m
0.8 m
Safety factor
1.4
1.6
1.7
Luminaire settings
Luminous flux
lm
Power / luminaire
W
Results are preliminary. The calculator does not account for all real-world factors affecting illumination.
Room preview
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How It Works
Calculation method and parameter guide
Room dimensions
Enter length, width, and ceiling height in metres. Floor area is calculated automatically and shown at the top.
Reflection coefficients
Select surface finish for ceiling, walls, and floor. Lighter surfaces (higher values) reflect more light, reducing how many luminaires are needed.
Illuminance (lx)
Target light level. Typical values: 100–200 lx corridors, 300–500 lx offices/classrooms, 500–1000 lx workshops/labs.
Working surface height
Height of the task plane above the floor. Use 0 m for floor level (warehouses), 0.8 m for standard desk height (offices).
Safety factor (maintenance factor)
Compensates for light loss over time (dirt, lamp aging). Use 1.4 for clean environments and 1.7 for dusty/industrial spaces.
Method: Uses the Utilisation Factor (lumen) method based on the work of G. M. Knorring. Assumes uniform luminosity of reflecting surfaces. For precise results, use specialist software such as DIALux or Relux.