Celsius (°C) is the most widely used temperature scale worldwide, where 0°C marks the freezing point of water and 100°C its boiling point at standard atmospheric pressure. It serves as the default temperature unit in nearly every country except the United States, appearing in weather forecasts, cooking instructions, and scientific literature. To convert Celsius to Fahrenheit, multiply by 9/5 and add 32.

Fahrenheit (°F) is a temperature scale where 32°F marks the freezing point of water and 212°F its boiling point, primarily used in the United States for weather, cooking, and everyday temperature references. It offers finer granularity than Celsius, with each degree representing a smaller temperature change. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9.