Lux to Lumen Calculator

Lux to Lumen Calculator: Convert Illuminance to Luminous Flux

Our free online Lux to Lumen calculator helps you convert illuminance (lux) to luminous flux (lumens) quickly and accurately. Whether you're working on lighting design, photography, or any project involving light measurements, this tool provides instant conversions with detailed explanations.

Understanding Lux and Lumens

Lux (lx) is a unit of illuminance that measures how much light falls on a surface per unit area. It represents the amount of light that reaches a specific area, making it crucial for determining if a space has adequate lighting.

Lumen (lm) is a unit of luminous flux that measures the total amount of light emitted by a light source in all directions. It represents the total "brightness" output of a light source.

The Conversion Formula

The relationship between lux and lumens depends on the area being illuminated. The conversion formula is:

Lumen = Lux × Area (m²)

Where:

Lux (lx) - Illuminance (light per unit area)
Area (m²) - Surface area in square meters
Lumen (lm) - Total luminous flux

How to Use the Calculator

Enter the lux value in the first input field
Enter the area in square meters in the second input field
The calculator will automatically compute the lumen value
View the detailed calculation breakdown

Practical Examples

Example 1: Office Lighting

An office desk area of 2 m² receives 500 lux of illumination.

Calculation: 500 lx × 2 m² = 1,000 lm

Example 2: Photography Studio

A photography backdrop of 4 m² needs 1,000 lux for proper exposure.

Calculation: 1,000 lx × 4 m² = 4,000 lm

Common Lux Levels for Different Applications

Application	Recommended Lux
General office work	300-500 lx
Detailed work (drafting, assembly)	750-1,000 lx
Reading	200-500 lx
Photography studio	1,000-2,000 lx
Outdoor daylight	10,000-25,000 lx

Why This Conversion Matters

Understanding the relationship between lux and lumens is essential for:

Lighting Design: Calculating the total light output needed for a space
Energy Efficiency: Determining the most efficient lighting solutions
Photography: Setting up proper studio lighting
Architecture: Ensuring adequate illumination in buildings
Safety: Meeting lighting standards for workplaces and public areas

Tips for Accurate Calculations

Always measure the actual area being illuminated
Consider the distance between the light source and the surface
Account for light loss due to reflection and absorption
Use consistent units (square meters for area)
Factor in the efficiency of your light fixtures

Frequently Asked Questions

What's the difference between lux and lumens?

Lux measures illuminance (light falling on a surface per unit area), while lumens measure luminous flux (total light output from a source). Lux is area-dependent, while lumens represent the total light output regardless of area.

Can I convert lumens to lux using this calculator?

This calculator converts lux to lumens. To convert lumens to lux, you would use the formula: Lux = Lumens ÷ Area (m²). You would need a different calculator for that conversion.

What's a good lux level for reading?

For comfortable reading, 200-500 lux is generally recommended. However, this can vary based on the type of reading material, age of the reader, and personal preference. Detailed work may require 750-1,000 lux.

How does distance affect lux measurements?

Lux decreases with the square of the distance from the light source (inverse square law). If you double the distance, the lux level becomes one-fourth. This is important when calculating lighting requirements for different areas.

Why is the area important in lux to lumen conversion?

Lux is illuminance per unit area, so the total luminous flux (lumens) depends on how much area is being illuminated. The same lux value over a larger area requires more total lumens from the light source.

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