Convert Celsius, Fahrenheit and Kelvin instantly. Type a temperature, pick the unit, and get all three values, plus a quick table of common temperatures.
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Fahrenheit
77°F
25 °C converts instantly to all three scales.
Celsius
25 °C
Fahrenheit
77 °F
Kelvin
298.15 K
Common temperatures
°C
°F
K
Reference
Fun check: -40° is where Celsius and Fahrenheit meet. Try it above.
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The conversion formulas
All three scales are linked by simple linear formulas:
°F = °C × 9/5 + 32
To go the other way:
°C = (°F − 32) × 5/9
Kelvin just shifts the Celsius scale so it starts at absolute zero:
K = °C + 273.15
Why three scales exist
Celsius sets 0° at water's freezing point and 100° at boiling, which is why most of the world uses it.
Fahrenheit survived in the US for everyday weather, where its smaller degrees feel more precise.
Kelvin starts at absolute zero (0 K = -273.15°C) and is the standard in science because it never goes negative.
What is the formula to convert Celsius to Fahrenheit?
Multiply the Celsius temperature by 9/5 (or 1.8) and add 32. So 25°C is 25 × 1.8 + 32 = 77°F. To go the other way, subtract 32 from Fahrenheit and multiply by 5/9.
At what temperature are Celsius and Fahrenheit the same?
Minus 40. -40°C equals -40°F, the one point where the two scales meet. It is a handy sanity check for any converter, including this one.
What is Kelvin and what is absolute zero?
Kelvin is the scientific temperature scale that starts at absolute zero, the coldest anything can theoretically get: 0 K, which is -273.15°C or -459.67°F. To convert Celsius to Kelvin, just add 273.15.
What is normal body temperature in Fahrenheit?
The long-standing reference is 37°C, which converts to 98.6°F. Modern studies put the average closer to 36.6°C (97.9°F), and anything from 97 to 99°F is considered normal variation.
Why does the US use Fahrenheit?
The US kept the Fahrenheit scale it inherited from Britain while most of the world switched to Celsius with metrication. For weather, Fahrenheit's finer degree steps feel intuitive to Americans, which is why it stuck for everyday use.