Temperature Converter: Celsius, Fahrenheit, Kelvin & Rankine
A fast four-scale temperature converter with live equivalents, exact formulas, clear scale definitions, and protection against impossible values below absolute zero.
Four temperature scales, one physical value
Celsius and Fahrenheit place zero at different reference points and use different degree sizes. Kelvin and Rankine begin at absolute zero; Kelvin uses Celsius-sized increments while Rankine uses Fahrenheit-sized increments.
Because the scales have offsets, temperature conversion cannot use one multiplication factor. The converter first maps the input to kelvin and then maps kelvin to the requested scale.
Absolute zero
Absolute zero is 0 K, equal to −273.15 °C, −459.67 °F, and 0 °R. A lower thermodynamic temperature is not valid, so the converter reports an error instead of returning a misleading result.
Examples
Water freezes
Input
0 °C
Show result
Result
32 °F, 273.15 K, or 491.67 °R
Same numerical reading
Input
−40 °C
Show result
Result
−40 °F
Frequently Asked Questions
What is 100 °C in Fahrenheit?
100 °C is 212 °F.
Can Celsius be negative?
Yes. Celsius and Fahrenheit can be negative, provided the temperature is not below absolute zero.
Is a change of 1 °C equal to a change of 1 K?
Yes. Celsius and kelvin increments have the same size, although their zero points differ.
References
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