This tool helps you estimate how many light fixtures a room needs based on its size and the required lux level. It uses the room area, target brightness, fixture lumen output, utilisation factor and maintenance factor to calculate the total lighting requirement. It gives a quick idea of the number of fittings needed for good illumination without doing a full lighting layout.
Lighting Lux Calculator
Calculate the number of luminaires needed from room dimensions and target lux level.
Choose a preset for common spaces below or enter a custom lux.
Fraction of lumens delivered to the working plane (typically 0.4–0.8)
Accounts for lamp aging, dirt and depreciation (0.7–0.9 typical)
Output rounds up to whole fixtures.
Formula used: Total lumens required = Area × Target lux. Number of fixtures = Total lumens required ÷ (Lumens per fixture × U × MF).
