How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. For example, 25 °C = 77 °F.
Temperature Converter
Switch between Celsius, Fahrenheit, and Kelvin for weather, cooking, science, and schoolwork.
Convert a temperature
Enter a temperature value and choose the source and target temperature scales.
About this converter
How to use Temperature Converter, plus the formulas and logic behind the results.
Tool description
The Temperature Converter switches between Celsius, Fahrenheit, and Kelvin. Unlike length or mass, temperature scales are offset as well as scaled, so a simple multiply-only conversion is not enough. Use it for weather, cooking, laboratory work, and school problems.
How to use
- Enter the temperature value.
- Select the scale of that value (Celsius, Fahrenheit, or Kelvin).
- Select the scale you want as the result.
- Select Convert. Kelvin values below 0 are rejected because they are below absolute zero.
Formulas
°C = (°F − 32) × 5/9°F = (°C × 9/5) + 32K = °C + 273.15°C = K − 273.15
Quick reference
- °F = (°C × 9/5) + 32
- °C = (°F − 32) × 5/9
- K = °C + 273.15
- °C = K − 273.15
Calculation logic
The calculator first converts the input to Celsius, then converts Celsius to the requested scale. This keeps a single internal reference and applies the correct offset and scale factor for Fahrenheit and Kelvin.
Absolute zero is 0 K (−273.15 °C). Kelvin values below zero are not physically meaningful.
Temperature Converter FAQ
Common questions about this converter and how to use the results.
How do I convert Fahrenheit to Celsius?
Subtract 32, then multiply by 5/9. For example, 68 °F = 20 °C.
How do I convert Celsius to Kelvin?
Add 273.15 to the Celsius temperature. For example, 0 °C = 273.15 K.
What is absolute zero?
Absolute zero is 0 K, equal to −273.15 °C or −459.67 °F.
When should I use Kelvin?
Kelvin is common in science and engineering because it starts at absolute zero.
Are temperature conversions linear?
Yes between Celsius and Kelvin. Fahrenheit uses a different scale factor and offset.