Convert lumen/square foot [lm/ft^2] to foot-candle [ft*c, fc] Online | Free lllumination Converter

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.

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.