Bathroom Mirror Vertical Illuminance Calculator Australia

Estimate face-plane vertical illuminance from mirror lighting output, fitting count, target area and maintained-light factors.

Mirror face

Mirror area, fitting output and vertical allowance

Enter the face area you want to light, not the whole bathroom. The result estimates vertical illuminance on the mirror or face plane and keeps wet-area approval out of the arithmetic.

Number of fittings in the lighting group.

Published output for one luminaire.

Approximate vertical face, mirror or reading surface area receiving the light.

Maintained lux target for the task or workplane.

Conservative allowance for light reaching the vertical target face.

Allowance for ageing, dirt and lumen depreciation.

Formula

vertical lux = fitting count x lumens per fitting x vertical UF x maintenance factor / target face area

Vertical illuminance is estimated from installed lumens, a vertical utilisation factor and maintenance factor, then divided by the face area. The result is a planning estimate for the mirror plane.

VariableTechnical meaningDesign check
Fitting countNumber of fittings or lamps serving the mirror.Count the face layer separately from the room light.
Fixture lumensOutput for one fitting.Use the exact schedule line or published output data.
Target areaApproximate face area on the mirror or in front of it.Measure the reflective face rather than the room floor.
Vertical UFConservative allowance for light reaching the face plane.Lower values suit offset or less direct lighting.
Maintenance factorAllowance for depreciation and dirt.Keep the factor visible beside the result.

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