Lighting Calculator

Visually choose your type of LED light fixture, enter parameters such as room dimensions, luminous flux, reflectance, suspension value, etc., and get a fast calculation of the average illuminance level or the quantity of luminaires you need for your indoor lighting projects. Adjust parameters as you wish.
Free app available in English, Spanish and French.

FORMULAS USED IN OUR CALCULATIONS

ROOM INDEX
Formula:
K = (A x B) / (H3 x (A + B))

Where:
A: Room length in m.
B: Room width in m.
H3: Mounting height of the luminaire from the working plane in m.

SUSPENSION FACTOR
Formula:
J = H2 / (H2 + H3)

Where:
H2: Distance between the ceiling and the light source of the luminaire in m.
H3: Distance between the light source of the luminaire and the working plane in m.

REFLECTION FACTORS
The light emitted by the luminaire is partially reflected by the walls of the illuminated room.
The choice of reflection coefficients (in %) is left at the discretion of the user.

PHOTOMETRIC CLASSES
Photometric classes used in this tool are predefined. They match most products available on the market for the same range of devices.

UTILANCE FACTOR
Ratio of the luminous flux received by the reference surface to the sum of the individual total fluxes of the luminaires of the installation. Depending on the suspension factor, the room index, the reflection factors and the photometric classes, we have determined the utilance factor according to the NFC 71-121 standard.

LIGHT LOSS FACTOR
Ratio of the average illuminance on the working plane after a certain period of use of a lighting installation to the average illuminance obtained under the same conditions for a new installation.
In our calculations, we have considered the decrease in lamp flux (due to dirt accumulation on luminaire and room surfaces and lamp depreciation). Thus, we have determined a light loss factor based on recommended practices.

LUMINOUS FLUX
Formula:
F = (E x A x B x D) / (η x Ui)

Where:
E: Illuminance level requested in lux.
A: Room length in m.
B: Room width in m.
D: Light loss factor.
η: Luminaire efficiency (light output ratio).
Ui: Utilance factor.

NUMBER OF LUMINAIRES
Formula:
N = F / f

Where:
N: Number of luminaires.
F: Total luminous flux to be emitted in lumens.
f: Luminous flux to be emitted by a device.

Please note that all results obtained with this app are provided for information only. They are intended to help you in making fast decisions. For projects strictly in accordance with the recommendations, a lighting calculation software based on the photometric files of the selected luminaires should be used.