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Interactive temperature laboratory
Temperature Converter and Scale Explorer
Convert a temperature once and see every major scale at the same time. Explore familiar reference points, inspect the formula and understand what the result means in everyday life.
5 scales · instant results · reference pointsConvert temperature
Enter a value and choose its scale. The result updates across Celsius, Fahrenheit, Kelvin, Rankine and Réaumur.
Converted temperature
Temperature in every scale
20 °C
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Highlighted result68 °F
Temperature range—
Nearest reference point—
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All equivalent values
Formula used—Calculation
—The scale conversions are mathematically exact before rounding. Water freezing and boiling points depend on pressure and purity, while body and appliance temperatures naturally vary.
Useful temperature reference points
Select a reference point to load it into the converter. Values for appliances and the human body are practical approximations.
Temperature conversion formulas
Temperature scales use both different interval sizes and different zero points. These formulas show the exact relationship between the most common scales.
Celsius to Fahrenheit
°F = °C × 95 + 32
Fahrenheit to Celsius
°C = (°F − 32) × 59
Celsius to Kelvin
K = °C + 273.15
Kelvin to Celsius
°C = K − 273.15
Celsius to Rankine
°R = (°C + 273.15) × 95
Rankine to Celsius
°C = (°R − 491.67) × 59
Celsius to Réaumur
°Ré = °C × 45
Réaumur to Celsius
°C = °Ré × 54
Kelvin and absolute temperature
The kelvin is the SI unit of thermodynamic temperature. Since 20 May 2019 it has been defined by fixing the numerical value of the Boltzmann constant, not by assigning an exact value to the triple point of water. A temperature difference of one kelvin is equal in size to one degree Celsius.
Kelvin uses the symbol K without a degree sign. Rankine is commonly written °R, and Réaumur is written °Ré.
Accuracy and important limits
The scale conversions are mathematically exact before rounding. Water freezing and boiling points depend on pressure and purity, while body and appliance temperatures naturally vary.
Weather
Compare forecasts from countries that use Celsius or Fahrenheit.
Cooking
Translate oven temperatures while allowing for appliance variation and fan-assisted settings.
Science
Use Kelvin for thermodynamic calculations and retain extra decimals until the final result.
Engineering
Confirm both the scale and whether a specification describes an absolute temperature or a temperature difference.
Temperature in everyday work
The same numeric value can mean very different things depending on the scale and the measurement context.
Related calculators and converters
Continue with apparent temperature, cooking measurements, energy conversion or the complete unit-converter directory.
Temperature Converter FAQ
How do I convert Celsius to Fahrenheit?
Multiply the Celsius value by 9/5 and add 32. For example, 20 °C equals 68 °F.
How do I convert Fahrenheit to Celsius?
Subtract 32 from the Fahrenheit value and multiply the result by 5/9. For example, 68 °F equals 20 °C.
Can Kelvin be negative?
A thermodynamic temperature cannot be below 0 K. A negative Kelvin input is therefore rejected as physically invalid.
Why is there no degree sign before K?
The SI unit name is kelvin and its symbol is K, so the correct form is 273.15 K rather than 273.15 °K.
Are water freezing and boiling points always exact?
The familiar 0 °C and 100 °C reference points assume standard atmospheric pressure. Actual phase-change temperatures vary with pressure and composition.
How accurate are the converted results?
The formulas are exact before display rounding. Choose more decimal places for technical work and round only the final value.