# How to Convert Among Celsius, Fahrenheit, and Kelvin

Celsius, Fahrenheit, and Kelvin are three scales for measuring temperature. The Fahrenheit scale was developed by the German physicist Daniel Gabriel Fahrenheit in 1724, predating both the Celsius and Kelvin systems.

Fahrenheit developed his scale so that 0°F was the temperature of the coldest solution he could make in his lab (a mixture of ice and ammonium chloride), and 100°F was the temperature of his wife. The scale was later refined so that the boiling point of water is exactly 212°F and the freezing point is exactly 32°F.

The Celsius and Kelvin scales are part of the metric system. The Celsius scale is based on the freezing and boiling points of water, with 0°C as the freezing point and 100°C as the boiling point. The Kelvin scale is a modification of the Celsius scale where 0°K is the lowest theoretically achievable temperature, absolute zero.

In the US, Fahrenheit is used to describe temperatures in everyday situations, while the Celsius scale is used in the sciences. Outside of the US, most countries use only the Celsius scale. You can easily convert among these scales using simple conversion formulas below or the calculator on the left.

**Fahrenheit to Celsius**:

5(F-32)/9 = C

**Celsius to Fahrenheit**:

32 + 9C/5 = F

**Fahrenheit to Kelvin**:

5(F-32)/9 + 273.15 = K

**Kelvin to Fahrenheit**:

32 + 9(K-273.15)/5 = F

**Celsius to Kelvin**:

C + 273.15 = K

**Kelvin to Celsius**:

K - 273.15 = C

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