Why was the original Celsius temperature scale inverted compared to the modern scale?
Anders Celsius's original scale was inverted: 0° marked water's boiling point and 100° marked its freezing point.
In 1742, Swedish astronomer Anders Celsius proposed a temperature scale with reversed logic—water boiled at 0° and froze at 100°. After his death in 1744, other scientists found this counterintuitive and flipped the scale to match our modern version, where higher numbers represent higher temperatures.
Nerd Mode
Swedish astronomer Anders Celsius first presented his temperature scale to the Royal Swedish Academy of Sciences in 1742. His original design, called the Centigrade scale, used inverted logic: 0° represented water's boiling point and 100° represented its freezing point at standard atmospheric pressure. This unconventional approach may have been designed to avoid negative numbers during Sweden's cold winters, keeping most temperatures within the 0–100 range.After Anders Celsius died in 1744, the scientific community recognized the scale's impracticality. Botanist Carl Linnaeus is often credited with ordering a reversed thermometer from instrument maker Daniel Ekström in 1745. By 1750, scientists including Jean-Pierre Christin and Marten Strömer had independently developed or promoted the intuitive version where 0° marks freezing and 100° marks boiling.The scale remained officially called Centigrade for over two centuries, derived from Latin: centum (hundred) and gradus (steps). In 1948, the 9th General Conference on Weights and Measures formally renamed it Celsius to honor its inventor and eliminate confusion with other technical uses of centigrade. Today, the Celsius scale is the global standard for temperature measurement in science and everyday use worldwide, except in the United States and a handful of other territories.
Verified Fact
FP-0003872 · Feb 18, 2026