Scientists measure the brightness of a light source in units of candles or, when using the metric system, in candelas. The amount of illumination -- or illuminance -- a surface receives depends on the distance from the light source and the intensity of the light source. Illuminance is measured in either foot-candles or the metric system units of lux. You can readily change foot-candles to lux by using a simple numerical conversion factor.
The unit name foot-candle can be abbreviated as "fc" or "ftc."
Enter the numerical value of illuminance, in units of foot-candles, into the calculator. For example, if your illuminance value is 22 foot-candles, you would enter 22.
Multiply the value which you just entered by 10.76. This is the conversion factor between foot-candles and lux. In the above example, you would calculate 22 x 10.76 = 237.
Report the result of the previous calculation as the illuminance in units of lux. You have now converted the original value of illuminance in units of foot-candles to units of lux. The example would therefore be reported as 237 lux.
- The unit name foot-candle can be abbreviated as "fc" or "ftc."
About the Author
Michael Judge has been writing for over a decade and has been published in "The Globe and Mail" (Canada's national newspaper) and the U.K. magazine "New Scientist." He holds a Master of Science from the University of Waterloo. Michael has worked for an aerospace firm where he was in charge of rocket propellant formulation and is now a college instructor.