Temperature Converter

Temperature Converter - Free Online Celsius, Fahrenheit, Kelvin Conversion Tool

Convert between Celsius, Fahrenheit, and Kelvin temperature scales instantly with our free online temperature converter. Whether you are traveling abroad and need to interpret a weather forecast, cooking with a recipe from another country, or working on a science project that requires Kelvin, this tool gives you precise results in a single click.

Temperature conversion is one of the most common everyday calculations, particularly between Celsius and Fahrenheit. While most of the world uses Celsius for weather and daily life, the United States and a few other countries use Fahrenheit. Kelvin, the SI base unit of temperature, is essential in scientific and engineering contexts where absolute temperature is required.

How to Use This Temperature Converter

1. Enter the temperature value you want to convert in the input field.
2. Select the original temperature scale from the "From" dropdown (Celsius, Fahrenheit, or Kelvin).
3. Select the target temperature scale from the "To" dropdown.
4. Click the "Convert" button to see your result instantly.
5. Change the value or scales at any time to perform additional conversions.

Temperature Conversion Formulas

• Celsius to Fahrenheit: °F = (°C × 9/5) + 32
• Fahrenheit to Celsius: °C = (°F - 32) × 5/9
• Celsius to Kelvin: K = °C + 273.15
• Kelvin to Celsius: °C = K - 273.15
• Fahrenheit to Kelvin: K = (°F - 32) × 5/9 + 273.15
• Kelvin to Fahrenheit: °F = (K - 273.15) × 9/5 + 32

Common Temperature Reference Points

• Absolute zero: 0 K = -273.15 °C = -459.67 °F
• Water freezes: 0 °C = 32 °F = 273.15 K
• Human body temperature: 37 °C = 98.6 °F = 310.15 K
• Water boils: 100 °C = 212 °F = 373.15 K

Frequently Asked Questions

Q. How do I quickly estimate Fahrenheit from Celsius?

A. A useful shortcut is to double the Celsius value and add 30. For example, 20 °C becomes roughly 70 °F (the exact answer is 68 °F). This approximation works reasonably well for everyday temperatures between 0 °C and 40 °C. For precise conversions, use the exact formula: multiply by 9/5 and add 32, or simply use our converter above.

Q. Why do scientists use Kelvin instead of Celsius or Fahrenheit?

A. Scientists use the Kelvin scale because it starts at absolute zero, the lowest temperature theoretically possible, where all molecular motion ceases. This makes Kelvin an absolute scale with no negative values, which simplifies many physics and chemistry calculations. For example, gas law equations (such as the ideal gas law PV = nRT) require temperature in Kelvin to produce correct results. One Kelvin degree is the same size as one Celsius degree, so converting between them only requires adding or subtracting 273.15.

Q. At what temperature are Celsius and Fahrenheit equal?

A. Celsius and Fahrenheit are equal at -40 degrees. That is, -40 °C is exactly the same as -40 °F. This is the only point where the two scales intersect. You can verify this by applying the formula: (-40 × 9/5) + 32 = -72 + 32 = -40. This temperature is extremely cold and is occasionally experienced in arctic and subarctic regions during winter.