Temperature Converter

Key Temperature Reference Points

Conversion Formulas

Understanding Temperature Scales

Temperature is a fundamental physical quantity that measures the average kinetic energy of particles in a substance. Unlike length or mass conversions that use simple multiplication factors, temperature conversions involve both scaling and offsetting because different scales have different zero points and degree sizes. Several temperature scales have been developed throughout history, each serving different practical or scientific purposes.

Common Scales

• Celsius (°C): Defined by the freezing point of water at 0 °C and the boiling point at 100 °C under standard atmospheric pressure. Proposed by Anders Celsius in 1742 and used worldwide for everyday and scientific purposes. It is the most widely adopted temperature scale globally.
• Fahrenheit (°F): Defined by Daniel Gabriel Fahrenheit in 1724. Water freezes at 32 °F and boils at 212 °F. Primarily used in the United States and a few other countries for weather, cooking, and daily life.
• Kelvin (K): The SI base unit of thermodynamic temperature. Its zero point (0 K) is absolute zero — the lowest possible temperature where all molecular motion ceases. One kelvin has the same magnitude as one degree Celsius. Since 2019, the kelvin is defined by fixing the Boltzmann constant at exactly 1.380649 × 10⁻²³ J/K.

Historical & Scientific Scales

• Rankine (°Ra): An absolute temperature scale using Fahrenheit-sized degrees. 0 °Ra = absolute zero. Used in some engineering fields in the United States, especially in thermodynamics and the aerospace industry.
• Delisle (°De): Invented by Joseph-Nicolas Delisle in 1732. Notably, this scale runs in reverse: higher numbers indicate colder temperatures. Water boils at 0 °De and freezes at 150 °De.
• Newton (°N): Proposed by Isaac Newton around 1700. Water freezes at 0 °N and boils at 33 °N. One of the earliest attempts to define a temperature scale with reproducible fixed points.
• Réaumur (°Ré): Created by René Antoine Ferchault de Réaumur in 1730. Water freezes at 0 °Ré and boils at 80 °Ré. Was widely used in Europe, especially France and Germany, until the mid-20th century.
• Rømer (°Rø): Devised by Ole Rømer in 1701, it is believed to have directly inspired Fahrenheit's scale. Water freezes at 7.5 °Rø and boils at 60 °Rø.

Practical Applications

References

The conversion formulas used in this calculator are based on internationally recognized definitions and scientific standards:

• BIPM - SI Base Units: The Kelvin (Bureau International des Poids et Mesures)
• NIST - SI Units of Temperature
• NIST Guide to SI - Conversion Factors
• Encyclopaedia Britannica - Temperature
• American Institute of Physics - History of Temperature Scales

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