Convert flame to centimeter-candle [cm*c] Online | Free lllumination Converter

A Historical Unit of Luminous Intensity

The flame is a traditional, non-SI unit used historically to measure luminous intensity, based on the light emitted by a standard flame, typically from burning a specific fuel under controlled conditions. It originated before the invention of modern light measurement devices and provided a practical way to describe light brightness using everyday sources.

One “standard flame” was defined by the intensity of light from a candle burning colza oil or other specified fuels. Although exact values varied by region and standardization efforts, the flame served as a common reference for brightness in industries like lighting, photography, and early scientific research.

With the advent of electric lighting and precise photometric units like the candela, the flame unit fell out of use. The candela, now the SI base unit for luminous intensity, provides a reproducible and universal standard far more accurate than flame-based measures.

Today, the flame unit is mainly of historical interest, helping us understand how people quantified light before modern technology. It also reflects the evolution of photometry from subjective, practical measures to objective, scientific standards.

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.