Convert centimeter-candle [cm*c] to foot-candle [ft*c, fc] Online | Free lllumination Converter

A Historical Unit of Illuminance

The centimeter-candle (cm·c) is an older, non-SI unit of illuminance that measures the luminous flux falling on a surface area of one square centimeter. It is defined as the illuminance produced at a distance of one centimeter from a uniform point source of one candlepower (now replaced by the candela).

Since the centimeter-candle measures light intensity over a very small area, it represents a much finer scale compared to more common units like the foot-candle or lux. One centimeter-candle is equivalent to 10,000 lux because one square meter contains 10,000 square centimeters.

Historically, the centimeter-candle was used in photometry and lighting sciences before international standardization led to the widespread adoption of the lux as the preferred illuminance unit. Its usage today is rare and mostly of historical interest, but it remains useful for understanding older lighting data and certain precise scientific contexts where small-area measurements matter.

Understanding centimeter-candle helps bridge the gap between historical and modern units of light measurement and offers insight into the evolution of photometric standards.

A Unit of Illuminance

The foot-candle (ft·c or fc) is a unit of illuminance used primarily in the United States and some other countries that follow imperial measurements. It measures the amount of luminous flux (light) falling on a surface of one square foot. One foot-candle is defined as one lumen per square foot.

Foot-candles are commonly used in lighting design, architecture, photography, and workplace safety to ensure spaces have appropriate lighting levels. For example, an office workspace typically requires around 30 to 50 foot-candles to provide sufficient brightness for tasks without causing eye strain. Retail stores and hospitals may require higher levels, while hallways or staircases might have lower standards.

Foot-candles are related to the metric unit lux, where 1 foot-candle equals approximately 10.76 lux (lumens per square meter). Understanding foot-candle measurements allows designers and engineers to plan lighting layouts effectively, balancing energy use with visual comfort.

Despite the growing global adoption of the lux, foot-candles remain prevalent in industries and regions that use imperial units, making it important for professionals to be familiar with both.