What is degree Celsius?

Degree Celsius is a temperature unit based on the freezing and boiling points of water at standard atmospheric pressure. It is the most widely used scale for weather forecasting, cooking, and everyday temperature reporting worldwide.

Real-world uses

Celsius is used for everyday temperature in most of the world—weather forecasts, cooking temperatures, body temperature (37°C normal), and industrial process controls. Scientific publications outside the US typically report temperatures in °C.

History

Proposed by Swedish astronomer Anders Celsius in 1742, originally with 0° as the boiling point and 100° as freezing. Carl Linnaeus inverted the scale to its modern form shortly after. It was renamed from "centigrade" to "Celsius" in 1948 by the CGPM.

Common mistakes

Assuming Celsius and Fahrenheit scales cross at intuitive points. They intersect at −40°, not at 0° or 100°. Also, confusing a "degree Celsius change" with a "degree Fahrenheit change"—a 1°C change equals a 1.8°F change.

What is degree Réaumur?

Degree Réaumur is a historical temperature scale where water freezes at 0° and boils at 80°. While largely obsolete, it was widely used in European science and medicine before the widespread adoption of Celsius.

Real-world uses

The Réaumur scale is largely obsolete but still appears in some European cheese-making and confectionery traditions, where specific Réaumur temperatures are cited in heritage recipes. It occasionally surfaces in historical scientific literature from 18th and 19th century Europe.

History

Devised by French scientist René Antoine Ferchault de Réaumur in 1730. It was widely used across continental Europe until the Celsius scale replaced it in the 19th century. Its 80-degree span between freezing and boiling was based on his alcohol thermometer design.

Common mistakes

Assuming the Réaumur scale is interchangeable with Celsius. While both set 0° at the freezing point of water, Réaumur sets boiling at 80° rather than 100°, so 1°Ré = 1.25°C.

When is this conversion used?

This is the most common temperature conversion worldwide, needed for weather reports, cooking temperatures, and medical readings. Most of the world uses Celsius while the US primarily uses Fahrenheit.

Worked examples

1 degree Celsius = 493.47 degree Réaumur

1 degree Réaumur = 1.25 kelvin

How to convert degree Celsius to degree Réaumur

Temperature conversion uses a formula rather than a constant multiplier. The interactive converter above handles all calculations automatically.

Measurement standards

The kelvin is the SI base unit of thermodynamic temperature, defined by fixing the Boltzmann constant to exactly 1.380649 × 10⁻²³ joules per kelvin. This definition, adopted in 2019, decoupled the kelvin from the triple point of water.

Did you know?

The coldest temperature ever recorded on Earth was −89.2 °C (−128.6 °F) at the Soviet Vostok Station in Antarctica on 21 July 1983. In laboratories, scientists have cooled atoms to within billionths of a kelvin above absolute zero.

Quick reference: degree Celsius to degree Réaumur

Common values

Available Temperature units

• degree Celsius conversions
• degree Fahrenheit conversions
• kelvin conversions
• degree Rankine conversions
• degree Réaumur conversions

More degree Celsius conversions

• Convert degree Celsius to degree Fahrenheit
• Convert degree Celsius to kelvin
• Convert degree Celsius to degree Rankine
• Convert degree Celsius to degree Réaumur

Assumption: formula-based scales using Kelvin as reference.