Convert Réaumur to Delisle

Convert Réaumur (°Ré) to Delisle (°De) instantly and accurately.

Conversion Formula

°De = (80 − °Ré) × 15/8

About Réaumur

Réaumur (°Ré) was developed by French scientist René Antoine Ferchault de Réaumur in 1730 and was widely used across Europe until the 19th century. The scale sets water's freezing point at 0°Ré and boiling point at 80°Ré, creating a more compressed scale than Celsius. While largely obsolete today, it's still occasionally used in specific industries like cheese-making, brewing, and candy production in some European countries. For perspective: room temperature is about 16°Ré, body temperature is roughly 30°Ré, and a hot summer day reaches 32°Ré. The conversion is straightforward: °Ré = °C × 4/5.

About Delisle

Delisle (°De) was created by French astronomer Joseph-Nicolas Delisle in 1732 and used in Russia for nearly a century before metrication. Uniquely, the scale is inverted: it increases as temperature decreases. Water boils at 0°De and freezes at 150°De - the opposite of Celsius. Delisle calibrated his mercury thermometer against the boiling point of water, assigning it zero. The scale was adopted by the Russian Academy of Sciences and used by astronomers and naturalists across the Russian Empire throughout the 18th century. It still appears in historical scientific records from that era.

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