Residential presets are suggestions. Workplace targets reference EN 12464-1; CU and MF account for losses. The grid and uniform-cone lux estimate do not verify glare, uniformity or compliance; use fixture photometry.
How to use
- Enter the dimensions and electrical values.
- Adjust the assumptions to match your components.
- Read the result and check the technical limits below.
Formula and assumptions
Φ = E × A / (CU × MF); N ≥ Φ/Φ_spot; D = 2h × tan(θ/2); E_axis ≈ Φ / [2π(1 − cos(θ/2))d²].
Calculated example
- Area
- 20 m²
- Target illuminance
- 150 lx
- Lumens per downlight
- 600 lm
- Ceiling height
- 2.7 m
- Working plane height
- 0.8 m
- Utilization factor CU
- 60 %
- Maintenance factor MF
- 80 %
- Required luminous flux
- 6250 lm
- Downlights in grid
- 12