 International Temperature Scale of 1990

The International Temperature Scale of 1990 is a practical scale for reproducible temperature measurements. Its assigned reference points and interpolation procedures approximate thermodynamic temperature. A calibrated standard platinum resistance thermometer transfers this scale over specified intervals; it does not define the modern kelvin.^[ref]

The International Temperature Scale of 1990 (ITS-90) is a defined temperature scale used for calibrating thermometers and establishing temperature measurements in scientific and industrial applications. It was established by the Comité International des Poids et Mesures (CIPM) as the successor to earlier temperature scales, notably the IPTS-68 (International Practical Temperature Scale of 1968).