Temperature Converter

How to Use the Temperature Converter

The Temperature Converter transforms temperatures between Fahrenheit, Celsius, and Kelvin scales. Whether you are adjusting a recipe from an international cookbook, interpreting weather forecasts while traveling, or performing scientific calculations requiring Kelvin, this tool provides instant accurate conversions.

How to Convert

Enter a temperature value, select the source scale, and choose the target scale. The converter instantly shows the equivalent temperature. You can also see all three scales simultaneously for quick reference.

Conversion Formulas

Celsius to Fahrenheit: F = (C × 9/5) + 32. Example: 25 degrees C = (25 × 1.8) + 32 = 77 degrees F.

Fahrenheit to Celsius: C = (F - 32) × 5/9. Example: 98.6 degrees F = (98.6 - 32) × 0.5556 = 37 degrees C.

Celsius to Kelvin: K = C + 273.15. Example: 100 degrees C = 373.15 K.

Fahrenheit to Kelvin: K = (F - 32) × 5/9 + 273.15.

Reference Temperatures

Water freezes at 0 degrees C / 32 degrees F / 273.15 K. Water boils at 100 degrees C / 212 degrees F / 373.15 K. Normal body temperature is 37 degrees C / 98.6 degrees F. Room temperature is approximately 20-22 degrees C / 68-72 degrees F. Absolute zero is -273.15 degrees C / -459.67 degrees F / 0 K.

Quick Mental Math Tricks

For a rough Celsius-to-Fahrenheit conversion, double the Celsius value and add 30. This gives: 20 degrees C ≈ 70 degrees F (actual: 68). For Fahrenheit to Celsius, subtract 30 and halve: 80 degrees F ≈ 25 degrees C (actual: 26.7). These approximations work well for everyday weather temperatures.

When Each Scale Is Used

Fahrenheit is used in the United States and a few other countries for weather and cooking. Celsius is used by most of the world for everyday temperatures. Kelvin is used in science and engineering, particularly in physics and chemistry, as it starts at absolute zero and has no negative values.

Frequently Asked Questions

Q: At what temperature are Fahrenheit and Celsius equal?

A: Fahrenheit and Celsius are equal at -40 degrees. Setting the formulas equal: F = C, so C = (C × 9/5) + 32, solving gives C = -40. This is the only temperature where both scales read the same number.

Q: What is absolute zero?

A: Absolute zero (0 K = -273.15 degrees C = -459.67 degrees F) is the theoretical lowest possible temperature where all molecular motion ceases. It has been approached in laboratory conditions but never actually reached. It is the foundation of the Kelvin scale.

Q: Why does the U.S. use Fahrenheit?

A: The Fahrenheit scale was widely adopted in English-speaking countries in the 18th century. While most countries later switched to Celsius, the U.S. retained Fahrenheit for everyday use. Some argue Fahrenheit offers more granularity for weather temperatures since its degree increments are smaller.