How do you calculate Lux from Lumens?

To calculate Lux from Lumens, you need to know the area over which the light is spread. The formula is: Lux = Total Lumens / Surface Area in square meters. Our calculator does this for you automatically.

What is the difference between Lumens and Lux?

Lumens (lm) measure the total amount of visible light produced by a source (luminous flux). Lux (lx) measures the amount of that light falling onto a specific surface (illuminance). One Lux is equal to one Lumen per square meter.

How does beam angle affect Lux?

Beam angle has a major impact on Lux. A narrow beam angle concentrates the same number of lumens into a smaller area, resulting in a much higher Lux value (a brighter spot). A wide beam angle spreads the lumens out, resulting in a lower Lux value (a dimmer, more diffuse light).

How many Lux do I need for an office?

For general office work, a standard recommendation is around 500 Lux on the desk surface. For more detailed tasks, this can be higher, while hallways and common areas may be lower. This calculator can help you determine how many lumens you need to achieve your target Lux level.

Lumens to Lux Calculator | Convert Lumens to Lux Accurately

Instantly calculate the Lux (illuminance) on a surface from the Lumens of a light source. Our calculator works by surface area or by beam angle and distance.

By Surface Area By Distance & Angle

Luminous Flux (Lumens)

Surface Area

Luminous Flux (Lumens)

Distance to Surface

Beam Angle (°)

Resulting Illuminance

Your result will appear here…

About the Lumens to Lux Calculator

When choosing lighting for a room, a workspace, or any project, the “lumens” rating on the bulb is only half the story. Lumens tell you the total amount of light a source produces, but they don’t tell you how bright that light will actually be on a surface. That’s where illuminance, measured in Lux, comes in. The Lumens to Lux Calculator from TechnoCodex is a powerful tool designed to bridge this gap, answering the critical question: “How bright will my light be in my actual space?”

This is more than a simple converter; it’s a practical lighting design tool. It allows you to accurately calculate Lux from Lumens by factoring in the most important variables: the area you need to illuminate or the specific distance and beam angle of a spotlight. This makes it an indispensable resource for architects, lighting designers, photographers, horticulturalists, and anyone planning a home renovation. Stop guessing and start designing your lighting with data-driven precision.

How to Use the Lumens to Lux Calculator

Our calculator features two modes to handle the most common lighting scenarios.

1. Calculation by Surface Area:
This mode is perfect for general room lighting, like calculating the average brightness in an office or living room.

Enter Luminous Flux: Input the total Lumens of your light source(s).
Enter Surface Area: Input the total area of the surface you are illuminating (in square meters or square feet).
Calculate: The tool will provide the average Lux level across that entire surface.

2. Calculation by Distance & Beam Angle:
This mode is ideal for spotlights, downlights, or any directional light source.

Enter Luminous Flux: Input the Lumens of the bulb.
Enter Distance: Input the distance from the light source to the surface.
Enter Beam Angle: Input the beam angle of the bulb in degrees (this is usually on the product’s spec sheet). A common angle for floodlights is 120°.
Calculate: The tool will determine the Lux level at the center of the light beam.

Understanding the Key Concepts: Lumens vs. Lux

To use this tool effectively, it’s vital to understand the difference between these two terms:

Lumen (lm): This measures Luminous Flux, which is the total quantity of visible light emitted by a source. It’s a measure of the light bulb’s potential.
Lux (lx): This measures Illuminance, which is the concentration of that light falling onto a specific surface. One Lux is defined as one Lumen per square meter.

Think of it like spray paint. A can of paint (the Lumens) has a fixed amount of paint inside. If you spray a small spot, the paint will be thick and opaque (high Lux). If you spray a large wall, the same amount of paint will create a thin, transparent coat (low Lux). Our calculator does the math to determine the “thickness” of your light.

Common Use Cases and Applications

Interior Design & Architecture: Determine how many light fixtures (and of what lumen rating) are needed to achieve a target Lux level (e.g., 500 Lux for an office, 150 Lux for a hallway).
Photography & Videography: Calculate the illuminance of a key light on a subject based on its power, distance, and beam angle.
Retail & Display Lighting: Plan effective product highlighting by calculating the Lux level of spotlights on merchandise.
Horticulture (Indoor Growing): Ensure plants receive the required amount of light for healthy growth by calculating the Lux from grow lights at the canopy level.
Occupational Health & Safety: Verify that workspaces meet safety standards for minimum lighting levels to prevent accidents and eye strain.

By providing a practical and easy-to-use platform, the TechnoCodex Lumens to Lux Calculator empowers you to move from simply buying a light bulb to intelligently designing a lighting environment.