Convert temperatures between Celsius, Fahrenheit, Kelvin and Rankine. Instant, accurate results using standard scientific formulas.
Temperature can be measured on several different scales. The most common are Celsius, Fahrenheit and Kelvin. Each has its own zero point and unit size, so conversion requires simple formulas:
Celsius → Fahrenheit: °F = (°C × 9/5) + 32
Fahrenheit → Celsius: °C = (°F − 32) × 5/9
Celsius → Kelvin: K = °C + 273.15
Kelvin → Celsius: °C = K − 273.15
Celsius → Rankine: °R = (°C + 273.15) × 9/5
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Multiply the Celsius value by 9/5 (or 1.8) and add 32. Example: 25°C × 1.8 + 32 = 77°F. For a quick mental estimate, double the Celsius number and add 30.
Kelvin is an absolute scale that starts at absolute zero (the coldest possible temperature). Since it doesn't have a subjective 'zero point' like Celsius or Fahrenheit, it's expressed as a plain unit — just 'K' instead of '°K'.
Absolute zero is the lowest possible temperature, where all molecular motion theoretically stops. It equals 0 Kelvin, −273.15°C or −459.67°F. Nothing in the universe has ever been measured at exactly this temperature.
Fahrenheit is mainly used in the United States, its territories, the Bahamas, the Cayman Islands and Liberia. Most of the rest of the world uses Celsius as the standard for weather and daily life.
Rankine (°R) is an absolute temperature scale like Kelvin, but based on Fahrenheit degree sizes. It's primarily used in some engineering fields in the United States, especially in thermodynamics and aerospace.
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