Accurate Illuminance Conversion for Lighting Professionals

Illuminance is a measure of how much luminous flux—or light—is spread over a given area. It's a critical factor in fields like photography, architecture, lighting design, and horticulture. Our free Illuminance Converter is an essential tool for professionals and hobbyists who need to switch between different units of light measurement quickly and accurately. Whether you're working with the international standard of Lux, the imperial unit Foot-candle, or other scientific units, this tool ensures your calculations are precise.

Understanding and converting illuminance values is key to achieving correct camera exposure, meeting building lighting codes, designing comfortable spaces, or providing optimal light for plant growth. This converter simplifies the process, handling the complex math so you can focus on your work.

How to Use the Illuminance Converter

1. Enter Your Value: Type the numeric value of the illuminance you need to convert into the "From" field.
2. Select Units: Choose your starting unit (e.g., Lux) and the unit you want to convert to (e.g., Foot-candle) from the dropdown lists.
3. Convert: Click the "Convert Illuminance" button to get your precise result instantly.
4. Copy Result: Use the "Copy Result" button to easily transfer the converted value to your clipboard for use in your projects.

Frequently Asked Questions About Illuminance

How do you convert EV to lux?

Converting Exposure Value (EV) to lux is not direct as EV also depends on ISO speed. The formula is: Lux = 2.5 * 2^EV. This formula assumes a standard light meter calibration with a C constant of 250 and ISO 100. For example, an EV of 15 would be approximately 2.5 * 2^15 = 81,920 lux, which corresponds to bright sunlight.

How do you calculate illuminance?

Illuminance (E) is calculated by dividing the total luminous flux (Φ) in lumens that falls on a surface by the area (A) of that surface. The formula is E = Φ / A. The resulting unit is lumens per square meter, which is known as lux (lx). For example, if 1000 lumens are spread evenly over a 2 square meter surface, the illuminance is 1000 lm / 2 m² = 500 lux.

What is the difference between luminance and illuminance?

Illuminance is the amount of light that falls onto a surface (measured in lux or foot-candles). It describes how much the surface is 'lit up'. Luminance is the amount of light that is emitted or reflected off that surface in a particular direction (measured in candela per square meter). It describes how bright the surface appears to the eye. A white wall and a black wall in the same room have the same illuminance, but the white wall has much higher luminance because it reflects more light.

How to convert lumen into lux?

You cannot directly convert lumens to lux because they measure different things. Lumens are a measure of total light output from a source, while lux is a measure of light intensity over a specific area. However, you can calculate lux if you know the area: Lux = Lumens / Area (in m²). For example, a 500 lumen light source illuminating a 5 square meter area provides an average illuminance of 100 lux.

How many lux is full sun?

The illuminance from full, direct sunlight can vary depending on time of day, location, and atmospheric conditions, but it is typically between 100,000 and 120,000 lux. On an overcast day, this can drop significantly to around 1,000-2,000 lux. A typical well-lit office space is around 500 lux.