Advanced Illuminance Lux Calculator

Compute lux from lumens, area, distance, and angle. Review utilization, maintenance, and scenario comparisons instantly. Plan brighter spaces with accurate engineering outputs and charts.

Calculator Inputs

Calculation Focus

Lumens per Fixture (lm)

Number of Fixtures

Area (m²)

Mounting Distance (m)

Beam Angle (°)

Incidence Angle (°)

Utilization Factor

Maintenance Factor

Target Lux

Typical values: utilization factor 0.50–0.85, maintenance factor 0.70–0.90, offices often target 300–500 lux.

Example Data Table

Scenario	Lumens/Fixture	Fixtures	Area (m²)	UF	MF	Target Lux	Approx. Maintained Lux
Small Office	3600	2	12	0.72	0.80	300	345.60
Workshop Bay	5200	4	36	0.68	0.78	500	306.13
Retail Aisle	4100	6	45	0.75	0.82	400	336.20
Lab Zone	6000	6	42	0.76	0.85	750	553.14

Formula Used

1) Area Method

E = (Φ × UF × MF) / A

2) Point-Source Method

E = (I × cosθ / d²) × UF × MF

3) Luminous Intensity from Beam Angle

I = Φ / Ω, where Ω = 2π(1 − cos(beam angle / 2))

4) Required Lumens for a Target

Φ required = (Target Lux × Area) / (UF × MF)

Symbol meanings:

E is illuminance in lux, Φ is luminous flux in lumens, UF is utilization factor, MF is maintenance factor, A is area in square meters, I is luminous intensity in candela, θ is incidence angle, d is distance, and Ω is beam solid angle.

How to Use This Calculator

Choose the calculation focus you want to emphasize.
Enter lumens per fixture and total fixture count.
Input illuminated area, mounting distance, and beam angle.
Set incidence angle for tilted lighting conditions.
Enter utilization and maintenance factors based on design assumptions.
Provide a target lux value for compliance comparison.
Press calculate to show results above the form.
Review the chart, engineering note, and export files if needed.

Frequently Asked Questions

1) What does lux measure?

Lux measures illuminance. It shows how much luminous flux reaches each square meter of a surface.

2) Why are there several illuminance results?

Each method represents a different design view. Area method estimates average coverage, while point-source and beam-pool values show localized behavior.

3) What is the utilization factor?

Utilization factor estimates how effectively fixture output reaches the working plane after room shape, optics, spacing, and reflection effects.

4) Why is the maintenance factor important?

Maintenance factor accounts for aging, dirt, and output reduction. It converts initial lighting levels into more realistic maintained values.

5) Does beam angle change lux?

Yes. Narrow beams concentrate light into smaller areas, usually increasing localized lux at a given distance.

6) Can this calculator help size fixtures?

Yes. Use the target lux option to estimate total lumens and approximate fixture quantity for the selected area.

7) Is point-source lux always accurate for rooms?

Not always. It is best for spot estimates. Full room designs also depend on spacing, reflections, optics, and working plane geometry.

8) Which units should I enter?

Use lumens for flux, meters for distance, square meters for area, degrees for angles, and lux for the target.