Temperature Value

From Celsius (°C) Fahrenheit (°F) Kelvin (K)

To Celsius (°C) Fahrenheit (°F) Kelvin (K)

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Celsius (°C)

The Celsius scale, also known as the centigrade scale, is a temperature scale used by the International System of Units (SI). It was named after the Swedish astronomer Anders Celsius (1701–1744).

• 0°C is the freezing point of water
• 100°C is the boiling point of water (at standard atmospheric pressure)

Fahrenheit (°F)

The Fahrenheit scale is a temperature scale based on one proposed in 1724 by the physicist Daniel Gabriel Fahrenheit (1686–1736). It is used primarily in the United States.

• 32°F is the freezing point of water
• 212°F is the boiling point of water (at standard atmospheric pressure)

Kelvin (K)

The Kelvin scale is an absolute temperature scale used in scientific work. It was named after the Belfast-born physicist and engineer William Thomson, 1st Baron Kelvin (1824–1907).

• 0K is absolute zero (-273.15°C), the theoretical lowest temperature possible
• No degree symbol is used with Kelvin temperatures
• The size of one Kelvin is the same as one degree Celsius

Quick Approximations

For a rough Celsius to Fahrenheit conversion:

1. Double the Celsius temperature
2. Subtract 10% of this value
3. Add 32

Example: 20°C → 2×20 = 40 → 40-4 = 36 → 36+32 = 68°F (actual: 68°F)

Interesting Facts

• -40 is the only temperature where Celsius equals Fahrenheit
• The Kelvin scale has no negative temperatures
• The Celsius scale was originally defined the opposite way (0° for boiling, 100° for freezing) before being reversed in 1743