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Temperature Converter

Temperature conversion involves three scales in common use: Fahrenheit (US everyday), Celsius (worldwide scientific and most countries), and Kelvin (absolute scale for physics and chemistry). Our converter handles all three plus Rankine (engineering thermodynamics) with live conversion and reference points for common temperatures.

°C
°F
K

Common Reference Points

Celsius

Fahrenheit

Kelvin

Conversion Formulas

°F = (°C × 9/5) + 32

°C = (°F − 32) × 5/9

K = °C + 273.15

°C = K − 273.15

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About the Temperature Converter

Temperature conversion involves three scales in common use: Fahrenheit (US everyday), Celsius (worldwide scientific and most countries), and Kelvin (absolute scale for physics and chemistry). Our converter handles all three plus Rankine (engineering thermodynamics) with live conversion and reference points for common temperatures.

How to use it

  1. Enter any temperature value and select the scale.
  2. See instant conversion to all other temperature scales.
  3. Reference panel shows key temperatures: water freezing, boiling, body temperature, absolute zero.
  4. Use the weather widget: typical comfort ranges in both Fahrenheit and Celsius.

Formula & methodology

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. Rankine to Fahrenheit: °F = °R − 459.67. Key values: 0°C = 32°F = 273.15K. 100°C = 212°F = 373.15K. −40° is the same in both C and F.

Common use cases

  • International travel: understanding local weather in unfamiliar temperature scale
  • Cooking: converting oven temperatures between °F (US recipes) and °C (European)
  • Science: working with Kelvin for gas laws and thermodynamics
  • Weather: the −40° where Celsius and Fahrenheit coincide (trivia)
  • HVAC: refrigerant temperatures and efficiency calculations in Rankine

Frequently asked questions

Historical inertia — Fahrenheit was the dominant scale in English-speaking countries when the US was founded. The metric system (including Celsius) was largely adopted by other countries after WWII. The Metric Conversion Act (1975) made metrication voluntary in the US, and resistance from industries and public familiarity kept Fahrenheit in daily use. Scientists and medical professionals in the US use Celsius; everyday weather and cooking remain Fahrenheit.
Absolute zero (0 Kelvin = −273.15°C = −459.67°F) is the theoretical temperature at which all molecular motion stops. The third law of thermodynamics states that it is impossible to reach absolute zero in a finite number of steps — you can approach it but never quite get there. Scientists have cooled matter to within billionths of a degree of absolute zero using laser cooling and magnetic evaporative cooling techniques.

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