About

Facilities managers and compliance officers utilize this tool to verify that workplace lighting meets safety standards (e.g., OSHA or EN 12464). While manufacturers state the output of a bulb in Lumens (lm), regulations specify requirements in Lux (lx), which is the light actually received at the working plane.

This calculator applies the inverse square law logic to determine illuminance. It is optimized for on-site use, allowing engineers to input room dimensions or a specific surface area to see if the installed fixtures theoretically provide sufficient light. This serves as a vital cross-check for physical light meter readings.

Formulas

Illuminance is the Luminous Flux divided by the area over which it is spread:

E_v = Φ_vA

If "Room Mode" is used, Area A is calculated as:

A = L × W

Note: This assumes the light source is isotropic or that the Lumens value represents the flux falling specifically on that surface.

Reference Data

Environment	Standard Illuminance (lx)	Source Requirement (lm/m²)
Warehouses / Storage	100 - 150	100 - 150
General Office Work	500	500
PC Work / Reading	500 - 750	500 - 750
Precision Assembly	1000	1000
Operating Theatre	10000 - 100000	10000+

Frequently Asked Questions

No. This tool calculates direct illuminance based on the source output and area. Professional lighting software (like DIALux) is needed to calculate "Utilization Factors" that account for light bouncing off walls and ceilings.

Real-world losses are significant. Dirt on bulbs, old fixtures (Lumen Depreciation), and fixture efficiency (Light Loss Factor) reduce the actual light hitting the surface. Engineers often add a maintenance factor of 0.8 to the calculation.

If you are calculating based on a point source distance (not just room area), doubling the distance reduces the Lux to one-quarter of its original value (Inverse Square Law).

Currently, the Room Mode supports rectangular dimensions. For circular areas, calculate the area manually (πr²) and use the "Known Area" input mode.