Convert Delisle to Rømer

Convert Delisle (°De) to Rømer (°Rø) instantly and accurately.

Conversion Formula

°Rø = 60 − °De × 7/20

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.

About Rømer

Rømer (°Rø) was designed by Danish astronomer Ole Christensen Rømer in 1701, making it one of the earliest calibrated temperature scales using two fixed points. It sets water's freezing point at 7.5°Rø and boiling point at 60°Rø; the offset of 7.5 at freezing was chosen to avoid negative numbers during the coldest Danish winters. In 1708, Daniel Gabriel Fahrenheit visited Rømer and was directly inspired by his thermometer design to create the Fahrenheit scale. Body temperature on the Rømer scale is approximately 22.5°Rø. Though now obsolete, Rømer's scale holds an important place in thermometric history.

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