Illuminance Converter

About Illuminance Converter

Illuminance measures light on a surface. 500 lux = typical office. 10,000-25,000 lux = daylight.

How to use this calculator

1. Enter the illuminance value you know.
2. Choose the unit you are converting from, such as \(\\text{lux}\) or \(\\text{fc}\).
3. Choose the unit you want to convert to.
4. Read the result, and use the step-by-step explanation to check the conversion.

The formula explained

The key conversion here is \(1\\text{ fc} = 10.764\\text{ lux}\), which tells you how to change between foot-candles and lux. From that, you can convert by multiplying or dividing, depending on the direction.

• \(\\text{fc}\) = foot-candles, a unit of illuminance
• \(\\text{lux}\) = lux, a metric unit of illuminance
• \(\\text{phot}\) = phot, a CGS unit of illuminance

Step by step method

1. If you are converting \(\\text{fc}\) to \(\\text{lux}\), multiply by \(10.764\).
2. If you are converting \(\\text{lux}\) to \(\\text{fc}\), divide by \(10.764\).
3. For \(\\text{phot}\), use the unit relationship shown by the converter to move between \(\\text{phot}\), \(\\text{lux}\), and \(\\text{fc}\).

Worked example

Problem. Convert \(25\\text{ fc}\) to \(\\text{lux}\).

1. Start with \(25\\text{ fc}\).
2. Use \(1\\text{ fc} = 10.764\\text{ lux}\), so \(25 \\times 10.764 = 269.1\).
3. The result is \(269.1\\text{ lux}\).

Tips and common mistakes

• Be careful about direction, because multiplying and dividing are opposite depending on which unit you start with.
• Check the unit in the final answer, since \(\\text{lux}\), \(\\text{fc}\), and \(\\text{phot}\) are not interchangeable without conversion.

Frequently asked questions