Lux to Footcandles Calculator

How the Lux to Footcandles Calculator Works

The lux to footcandles calculator converts illuminance values from lux (lx) to footcandles (fc), facilitating accurate lighting assessments across different measurement systems. This tool is essential for professionals working in international contexts, ensuring consistency in lighting design and compliance with regional standards.

By inputting a value in lux, the calculator multiplies it by the conversion factor to yield the equivalent footcandle value. This straightforward process aids in translating lighting requirements between the metric and imperial systems.

Understanding Lux and Footcandles

Lux and footcandles are units of illuminance, measuring the amount of light falling on a surface. A lux represents one lumen per square meter, commonly used in countries adhering to the International System of Units (SI). A footcandle denotes one lumen per square foot, primarily used in the United States. Both units quantify how well-lit a surface is, differing only in the area over which the light is distributed.

For instance, a workspace illuminated at 500 lux is receiving the same amount of light as one at approximately 46.45 footcandles, differing only in the measurement system used.

Conversion Formula

The conversion between lux and footcandles is based on the area difference between a square meter and a square foot.

• To convert lux to footcandles: footcandles = lux × 0.09290304

• To convert footcandles to lux: lux = footcandles × 10.76391

This conversion factor ensures accurate translation of illuminance values between the two systems.

Practical Examples

Example 1:

A reading of 100 lux needs to be converted to footcandles.

footcandles = 100 × 0.09290304 = 9.290304

Therefore, 100 lux equal approximately 9.29 footcandles.

Example 2:

An area has an illuminance of 50 footcandles, and you need to find the equivalent in lux.

lux = 50 × 10.76391 = 538.1955

So, 50 footcandles are approximately 538.20 lux.

Why Convert Between Lux and Footcandles?

Converting between lux and footcandles is crucial when working across regions that use different measurement systems. It ensures that lighting designs meet local standards and provides clarity in communication among international teams. Accurate conversions help maintain consistency in lighting levels, crucial for safety, productivity, and comfort.

Are Lux and Footcandles Interchangeable?

While lux and footcandles measure the same physical quantity—illuminance—they are not directly interchangeable due to their different base units (square meters vs. square feet). However, with the appropriate conversion factor, values can be accurately translated between the two, allowing for effective comparison and application in various contexts.

Illuminance Levels for Various Environments

Environment	Lux (lx)	Footcandles (fc)
Office Work	300–500	27.87–46.45
Classroom	300–750	27.87–69.68
Hospital Operating Room	1000–2000	92.90–185.80
Supermarket	750–1000	69.68–92.90
Residential Living Room	100–300	9.29–27.87
Street Lighting	10–20	0.93–1.86
Full Daylight (Indirect)	10,000–25,000	929.03–2322.58
Direct Sunlight	32,000–100,000	2972.90–9290.30

These values serve as guidelines for designing lighting systems that meet the specific needs of various environments.

Tips for Accurate Lighting Measurements

• Use a Calibrated Light Meter: Ensure your light meter is properly calibrated for accurate readings.

• Consistent Measurement Units: Stick to one measurement system (metric or imperial) throughout your project to avoid confusion.

• Consider Surface Reflectivity: Reflective surfaces can affect illuminance readings; account for this in your measurements.

• Document Conditions: Record the time of day, weather conditions, and other factors that might influence lighting levels during measurement.

By understanding and accurately converting between lux and footcandles, professionals can ensure optimal lighting conditions across various applications and regions.