Lighting & Illuminance Calculator

Work out how many lumens a room needs and how many light fixtures to install, from its floor area and a recommended light level. Pick a room-type preset to set the target in footcandles (and lux), or enter a custom value; then enter the lumens per fixture and the luminous efficacy to get the recommended fixture count and the electrical power. Useful for planning residential and commercial lighting, comparing LED lumen output, and estimating running watts. Pure arithmetic — the IES-recommended ranges are rules of thumb; real lighting design also weighs fixture height, beam angle, wall reflectance and task contrast. Everything runs locally in your browser.