Convert lumen/square foot [lm/ft^2] to nox 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 in Historical Use

Nox is an older, less commonly used unit of illuminance that measures the intensity of light falling on a surface. It is defined as one millilumen per square meter (1 mLm/m²) or equivalently, 0.001 lux. This means 1 nox is equal to one-thousandth of a lux.

The term “nox” comes from the Latin word for “night,” reflecting its use in describing very low levels of light, such as nighttime or dim environments. Although it is rarely used in modern lighting science, the nox still appears in some older literature and niche applications where extremely low light levels are important.

Understanding nox helps provide context for measuring and comparing very faint light intensities. For example, the illumination from a full moon on a clear night is roughly around 0.1 lux, or 100 nox.

While modern standards primarily use lux as the universal unit of illuminance, knowing about nox can be helpful when reading historical documents or dealing with precise measurements in low-light scenarios.