How to Convert Celsius, Fahrenheit, and Kelvin

Unlike conversions for weight or length, which scale directly from a shared starting point of zero, temperature conversion requires adjusting both the offset (the freezing/zero point) and the increment size of the degrees. The three primary global scales are Celsius, Fahrenheit, and Kelvin.

The Three Temperature Scales

• Celsius (°C): The standard metric scale used worldwide. It is calibrated around water: freezing at 0°C and boiling at 100°C under standard sea-level atmospheric pressure.
• Fahrenheit (°F): The primary scale in the United States. Under Fahrenheit, water freezes at 32°F and boils at 212°F.
• Kelvin (K): The scientific thermodynamic scale. It starts at absolute zero (0 K), which is the theoretical state of zero molecular motion. 0 K is equivalent to -273.15°C.

Temperature Conversion Formulas

Converting between these scales requires specific algebraic equations:

• Celsius to Fahrenheit:

  Fahrenheit = (Celsius × 9/5) + 32

• Fahrenheit to Celsius:

  Celsius = (Fahrenheit - 32) × 5/9

• Celsius to Kelvin:

  Kelvin = Celsius + 273.15

Conversion Example:

To convert a room temperature of 20°C into Fahrenheit: Fahrenheit = (20 × 1.8) + 32 = 36 + 32 = 68°F

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