How to Convert Celsius to Fahrenheit and Back

Celsius (°C) is used almost everywhere, while Fahrenheit (°F) is mainly used in the United States. So when reading American recipes, appliance manuals, or a weather forecast while traveling, you often need to convert one to the other. Let's go over the formula and a handy table.

Conversion formulas

Celsius to Fahrenheit:

°F = °C × 9/5 + 32

Fahrenheit to Celsius:

°C = (°F − 32) × 5/9

For example, 20 °C: 20 × 9/5 + 32 = 36 + 32 = 68 °F.

A quick mental shortcut

A rough estimate you can do in your head: multiply °C by 2 and add 30. For 20 °C, that gives 70 °F — close to the exact 68 °F. For everyday temperatures, that's often close enough.

Table of common values

Quick conversion online

To avoid doing the math by hand, especially with decimal values, use the temperature converter — enter a value in °C, °F, or Kelvin and get the rest instantly. Handy for recipes, appliances, and weather.

What about Kelvin

Science uses Kelvin (K): 0 K is absolute zero, and 0 °C = 273.15 K. The formula is simple: K = °C + 273.15. The temperature converter calculates that too.