The Kelvin temperature scale was the brainchild of Belfast-born British inventor and scientist William Thomson — also known as Lord Kelvin. It is one of the three best-known scales used to measure temperature and often used as a measure of the colour temperature of light sources.

Kelvin temperatures for commercial and residential lighting applications fall somewhere on a scale from 2000K to 6500K. The lower the light temperature rates on the Kelvin scale, the warmer and more red the light appears to the eye. The higher on the Kelvin scale a light rates, the ‘cooler’ and more blue the light appears.

2000K to 3000K – Warm white (red-orange to yellow-white).
3100K to 4500K – Cool/bright white (neutral-white to slight-blue tint).
4500K+ Moves towards a more “daylight” colour temperature (blue-white light that mimics daylight).