Use this engineering calculation for a transparent preliminary estimate or independent arithmetic check when geometry, materials, loads, operating conditions, and units are defined consistently.

Incident Lumens (lm)

Required number input.

Area Square Meters (m²)

Required number input.

Average illuminance in lux from uniformly distributed luminous flux incident on a surface area. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Illuminance Lux (lx)

The resulting illuminance lux returned as a number.

• Illuminance and lighting-power estimates depend on photometric files, geometry, reflectance, maintenance, daylight, controls, glare, spectrum, observer position, and code definitions. Lumens divided by area is not a complete lighting design.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check assumptions against drawings, measurements, current material data, and the applicable design code. Apply required load combinations and safety factors, then obtain qualified review and testing for consequential designs.

• Illuminance Uniformity

  Lighting uniformity ratio of minimum measured illuminance to average illuminance on the same measurement grid.

• Beam Reaction Uniform

  Each end reaction of a simply supported beam carrying a uniformly distributed full-span load.

• Biot Number

  Biot number hLc/k for a body with characteristic length Lc=volume/surface area supplied by the user.