Converters
Temperature Converter
Convert Celsius, Fahrenheit, and Kelvin temperatures.
Temperature Converter tool
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About This Tool
Convert a temperature between Celsius, Fahrenheit, and Kelvin without manually applying scale-specific formulas. Unlike ordinary length conversions, temperature scales have different zero points as well as different interval sizes. The tool calculates the selected conversion and shows the same temperature on all three scales, making it useful for weather comparisons, cooking references, classroom work, laboratory notes, and engineering checks.
How To Use It
- Enter the temperature value, including a negative value when appropriate.
- Choose whether the entered value is Celsius, Fahrenheit, or Kelvin.
- Choose the target scale and read the converted temperature.
- Use the comparison table to check the equivalent value on all supported scales, or use Swap when you want to reverse the selected conversion.
Examples
Water freezing point
Enter 0 Celsius and convert to Fahrenheit to get 32 °F. On the Kelvin scale the same temperature is 273.15 K.
Water boiling reference
Enter 100 Celsius and convert to Fahrenheit to get 212 °F, or to Kelvin to get 373.15 K. These familiar reference points are also useful for checking that the selected scales are correct.
Negative temperature
Enter -40 Celsius and convert to Fahrenheit. The result is also -40, the point where the Celsius and Fahrenheit scales have the same numeric value.
Useful Notes
Celsius and Fahrenheit use offsets
To convert Celsius to Fahrenheit, multiply by 9/5 and add 32. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9. The added or subtracted offset is why temperature cannot be converted with a single ratio alone.
Kelvin is an absolute temperature scale
Kelvin uses the same interval size as Celsius but starts at absolute zero. Convert Celsius to Kelvin by adding 273.15, and Kelvin to Celsius by subtracting 273.15. Kelvin values are conventionally written without a degree symbol.
Useful reference points
Water freezes at 0 °C, 32 °F, or 273.15 K and boils at 100 °C, 212 °F, or 373.15 K at standard atmospheric pressure. Actual boiling temperature changes with pressure and altitude.
Precision and rounding
Some conversions produce repeating decimals. The calculator keeps useful precision in the displayed result, but measurements should normally be rounded to match the precision of the original temperature reading.
FAQ
What is the Celsius to Fahrenheit formula?
Multiply the Celsius value by 9/5, then add 32. For example, 20 °C becomes 68 °F.
What is the Fahrenheit to Celsius formula?
Subtract 32 from the Fahrenheit value, then multiply by 5/9. For example, 68 °F becomes 20 °C.
Can I convert negative temperatures?
Yes. Negative Celsius and Fahrenheit temperatures are valid and supported. Kelvin represents an absolute scale, so physically meaningful Kelvin temperatures do not go below 0 K.
Why does Kelvin not use a degree symbol?
The SI unit name is kelvin and its symbol is K, not °K. Celsius and Fahrenheit values use degree symbols because they are degree-based scales.
At what temperature are Celsius and Fahrenheit equal?
The two scales have the same numeric value at -40: -40 °C equals -40 °F.