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

Indoor Lux (lx)

Required number input.

Outdoor Lux (lx)

Required number input.

Daylight factor as indoor daylight illuminance divided by simultaneous unobstructed outdoor illuminance, in percent. 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]

Daylight Factor Percent (%)

The resulting daylight factor percent returned as a number.

• Daylight factor is a static overcast-sky ratio and does not describe sunlight, glare, annual climate, shading controls, view quality, or electric-light interaction. Geometry, surface reflectance, glazing, dirt, and measurement point definitions matter.
• 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.

• Electrical Load Diversity

  Electrical load diversity factor as sum of individual noncoincident peaks divided by coincident system peak.

• Hydro Capacity Factor

  Hydropower capacity factor from actual generation in MWh divided by rated MW times interval hours.

• Ampacity Derated

  Adjusted current rating from a base ampacity times a supplied 0–1 derating factor; not a code sizing result.