Calculate the required lumens and number of lamps based on the room’s illumination intensity.
The Lighting Calculator tells you how much light a room needs and how many lamps should be installed. The calculation is based on the recommended illumination intensity (lux) for the room type and the size of the room.
The calculator is free, works in your browser without registration, and shows the result as soon as you change the values. The calculation is done on your own device, and the information you enter is not sent anywhere.
Required luminous flux (lm) = illumination intensity (lx) × area (m²) / usage factor. Number of lamps = required luminous flux / luminous flux of one lamp.
A 20 square meter living room (150 lx) and 800 lumen lamps: the required luminous flux is 5,000 lm, so you need 7 lamps. With default settings, the calculator gives the result: 7 lamps are needed.
For renovators, interior designers, and lighting planners who want to size the lighting correctly before purchasing fixtures.
Lux (lx) measures the light that hits a surface: 1 lx = 1 lumen per square meter.
For kitchen work surfaces, 300–500 lx is recommended, so a kitchen needs more light than a living room.
Not all of the lamp's light reaches the work surface. Reflections and the structure of the fixture reduce the output; 0.5–0.6 is a common value.