4000K

4000K is a correlated color temperature (CCT) used in lighting to describe the perceived color of white light. It is measured in kelvin (K) and indicates the hue of light produced by a theoretical filament at 4000 kelvin; in practice, modern lamps such as LEDs or fluorescents are specified as 4000K CCT. A 4000K light is typically described as neutral white with a subtle cool bias, sitting between warm white (2700–3000K) and daylight or cool white (5000–6500K) on common product charts. The exact appearance varies with spectral power distribution and rendering indices.

Applications of 4000K lighting are common in offices, retail spaces, laboratories, and classrooms where clear visibility and color discrimination are important, though preferences vary by region and application. It is often chosen for task lighting and general ambient illumination, balancing energy efficiency with a clean, unobtrusive look.

Technical notes: CCT is independent of brightness and color rendering index (CRI), though both influence perceived light quality. In practice, 4000K LED fixtures may offer CRI ratings around 80–90, with higher ratings for specialized products. Some manufacturers label 4000K simply as neutral white; variants around 3800–4200K may be marketed as 4000K, so buyers should verify the color appearance by viewing product samples or chromaticity coordinates.

See also: Color temperature, Kelvin scale, lighting, CRI.