Temperature converter
Convert between Celsius, Fahrenheit, Kelvin and Rankine, then watch the thermometer climb past freezing, body heat, boiling water and a pizza oven.
That's about the temperature of a warm room. Comfortable room temperature.
What it means
How warm is that?
Reference temperatures are typical values at sea level. Water boils lower up a mountain, where the air pressure is less.
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Your temperature in every unit
Learn
Three things worth knowing
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Double it and add 30
To get Fahrenheit from Celsius quickly: double, then add 30. For 20 °C that gives 70 °F against the true 68 °F, close enough to pick an outfit.
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Fahrenheit started with brine
Daniel Fahrenheit set 0° at the coldest temperature he could reach with ice, water and salt, and about 96° at body heat. Celsius later used water itself: 0 for melting, 100 for boiling.
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Degrees and differences
A temperature of 10 °C converts to 50 °F, but a rise of 10 °C is a rise of 18 °F, not 50. For differences you multiply by 1.8 and skip the offset.
Shortcuts
Popular temperature conversions
Background
About temperature units
Nearly every country reports weather in Celsius; the United States uses Fahrenheit. Science uses Kelvin, which starts at absolute zero, the point where particles have the least possible energy.
Celsius and Fahrenheit both have arbitrary zero points, which is why converting needs an offset as well as a multiplication, and why ratios like “twice as hot” are meaningless.