What is the Celsius scale?

Celsius (°C) is a temperature scale where 0°C is the freezing point of water and 100°C is the boiling point, both at standard atmospheric pressure. It is used by most countries worldwide for everyday temperature measurement and is the standard in science.

Who invented the Celsius scale?

Swedish astronomer Anders Celsius proposed his temperature scale in 1742. Originally, he set 0 as the boiling point and 100 as the freezing point. After his death, fellow scientists inverted the scale to the form used today.

Is Celsius the same as centigrade?

Yes. 'Centigrade' was the original name (from Latin 'centum' = 100, 'gradus' = step). In 1948, it was officially renamed 'Celsius' to honor Anders Celsius and to avoid confusion with a unit of angle measurement also called 'centigrade.'

What Is Celsius? Temperature Scale Definition & History

Definition

The Celsius scale (symbol: °C) is a temperature scale based on two reference points:

0°C: Freezing point of water at standard pressure
100°C: Boiling point of water at standard pressure

The 100-degree interval between these points is divided into equal degrees.

Key Temperature Reference Points

Description	Celsius	Fahrenheit
Absolute zero	−273.15	−459.67
Extremely cold weather	−40	−40
Water freezes	0	32
Refrigerator	4	39
Comfortable room	21	70
Body temperature	37	98.6
Hot day	40	104
Water boils	100	212

Celsius vs Kelvin

The Celsius and Kelvin scales have the same degree size, but different zero points. Kelvin starts at absolute zero: K = °C + 273.15. The Kelvin scale is used in scientific contexts where negative temperatures would be confusing.

Countries Using Celsius

Nearly every country uses Celsius for everyday temperatures. The United States is the most notable exception, using Fahrenheit for weather, cooking, and medicine. Liberia and a few US territories also use Fahrenheit.

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