Convert centimeter-candle [cm*c] to lumen/square foot [lm/ft^2] 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.

Measuring Illuminance

Lumen per square foot (lm/ft²) is a unit of illuminance, representing the amount of luminous flux (light) falling on a surface area of one square foot. It measures how brightly an area is illuminated, helping to quantify the perceived brightness for human vision.

This unit is commonly used in lighting design, architecture, and workplace safety to ensure adequate and comfortable lighting conditions. For example, offices, classrooms, and public spaces have recommended illuminance levels expressed in lm/ft² to optimize visibility and reduce eye strain.

Illuminance measured in lm/ft² is closely related to the SI unit lux, which is lumens per square meter (lm/m²). Since one square foot equals approximately 0.0929 square meters, 1 lm/ft² is about 10.76 lux.

Designers use lm/ft² to plan lighting layouts, select appropriate fixtures, and evaluate energy efficiency. Proper illuminance levels contribute to productivity, safety, and aesthetics by ensuring spaces are neither too dim nor overly bright.

Understanding lumen per square foot helps balance lighting quality and energy consumption, making it a vital concept in modern lighting engineering.