Convert lumen/square meter [lm/m^2] to meter-candle [m*c] Online | Free lllumination Converter

The Standard Unit of Illuminance

Lumen per square meter (lm/m²), also known as lux, is the standard unit used to measure illuminance, which is the amount of luminous flux (light) falling on a surface per unit area. One lux equals one lumen distributed over one square meter, quantifying how brightly a surface is illuminated.

Lux is widely used in lighting design, architecture, photography, and occupational health to ensure proper lighting conditions for various environments. For instance, office spaces typically require around 300-500 lux to provide comfortable and efficient lighting for work, while outdoor daylight can range from 10,000 to over 100,000 lux.

Understanding illuminance in lux helps in designing lighting systems that optimize visibility, safety, and energy consumption. It allows engineers and designers to calculate how much light a space receives and adjust fixtures or bulbs accordingly.

Lux is preferred globally because it aligns with the metric system and provides a clear, standardized measure of light intensity on surfaces, making it essential for ensuring consistent and effective lighting in both indoor and outdoor settings.

A Traditional Unit of Illuminance

The meter-candle (m·c) is a historical unit of illuminance that measures the luminous flux falling on a surface area of one square meter from a uniform point source with an intensity of one candlepower (now replaced by the candela) placed one meter away. It was used primarily before the international adoption of the lux as the standard unit for illuminance.

One meter-candle is roughly equivalent to one lux, since lux is defined as lumens per square meter. However, the meter-candle historically provided a more intuitive measure of illuminance based on the distance from a known light source, which was practical for early lighting calculations and designs.

While the meter-candle is largely obsolete today, replaced by the lux in most scientific and engineering applications, it remains a useful reference when interpreting older lighting standards, manuals, and specifications.

Understanding the meter-candle helps in grasping the evolution of lighting measurement units and appreciating the advances in photometric science that have led to more precise and standardized units.