Angle at which light is emitted from a lamp or fixture, affecting how spread out or focused the light is.

Unit of luminous intensity, measuring the intensity of light emitted in a specific direction.

Scale (0-100) that measures how accurately a light source displays colors in comparison to natural daylight.

Color appearance of light, measured in Kelvin (K), ranging from warm (below 3,000 K) to cool (above 5,000 K).

Unit of illumination, equal to one lumen per square foot, commonly used in the U.S.

Excessive brightness causing discomfort or visual impairment. Often minimized with diffusers or shields.

Measure of brightness from a light source which is taken through a light meters sensor at a horizontal position on a horizontal surface

Total amount of visible light illuminating a point on a surface from all directions above the surface

Refers to how light is spread across an area, including direct, diffuse, or mixed types of distribution.

Unit of measurement for the total amount of visible light emitted by a source. Higher lumens indicate brighter light.

Ratio of luminous flux to electrical power. Higher efficacy means more light output per watt.

Total quantity of light emitted by a source, measured in lumens (lm).

Unit of illumination, equal to one lumen per square meter. It measures the amount of light that falls on a surface.

Describes the uniformity of light levels across an area. May be expressed as a ratio of average to minimum or maximum to minimum level of illumination for a given area. Lowest level of illumination should be no less than 1/4 the maximum level of illumination (4:1)

Measure of brightness from a light source which is taken through a light meters sensor at a vertical position on a vertical surface

Measure of electrical power consumed by a light source. It represents the energy used by the bulb.