Convert between Celsius (°C), Fahrenheit (°F), and Kelvin (K) instantly. Used by 50,000+ people daily for weather, cooking, and science.
Our free temperature converter helps you quickly convert between Celsius (°C), Fahrenheit (°F), and Kelvin (K) with high precision. Whether you're checking weather forecasts, following a recipe, conducting scientific experiments, or traveling internationally, this tool provides instant, accurate temperature conversions.
The Celsius scale, also known as centigrade, is used by most countries worldwide for everyday temperature measurements. It was developed by Swedish astronomer Anders Celsius in 1742. Water freezes at 0°C and boils at 100°C at standard atmospheric pressure.
The Fahrenheit scale is primarily used in the United States and its territories. It was developed by German physicist Daniel Gabriel Fahrenheit in 1724. Water freezes at 32°F and boils at 212°F at standard atmospheric pressure. The scale was based on a mixture of ice, water, and ammonium chloride (0°F) and human body temperature (96°F, later adjusted to 98.6°F).
The Kelvin scale is the base unit of temperature in the International System of Units (SI). It is used primarily in scientific applications. Lord Kelvin (William Thomson) developed the scale in 1848. Zero Kelvin (0K) is absolute zero - the theoretical temperature at which all molecular motion stops. Kelvin uses the same increments as Celsius but starts at absolute zero (0K = -273.15°C).
To convert Celsius to Fahrenheit, multiply the Celsius temperature by 9/5 (1.8) and then add 32. For example: 25°C × 9/5 = 45, 45 + 32 = 77°F.
Quick rule of thumb: Double the Celsius temperature and add 30 for an approximate Fahrenheit value. (25 × 2 = 50, 50 + 30 = 80°F, close to 77°F)
To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit temperature, then multiply by 5/9. For example: 77°F - 32 = 45, 45 × 5/9 = 25°C.
Quick rule of thumb: Subtract 30 from Fahrenheit and divide by 2 for an approximate Celsius value. (77 - 30 = 47, 47 ÷ 2 = 23.5°C, close to 25°C)
To convert Celsius to Kelvin, simply add 273.15 to the Celsius temperature. For example: 25°C + 273.15 = 298.15K.
The normal human body temperature is approximately 37°C (98.6°F). However, normal body temperature can vary from person to person and throughout the day, typically ranging from 36.5°C to 37.5°C (97.7°F to 99.5°F).
Pure water freezes at 0°C (32°F) at standard atmospheric pressure. This is one of the defining points of the Celsius and Fahrenheit scales.
Pure water boils at 100°C (212°F) at standard atmospheric pressure (sea level). At higher altitudes where atmospheric pressure is lower, water boils at lower temperatures.
Absolute zero is the lowest possible temperature, theoretically the point at which all molecular motion stops. It is defined as 0 Kelvin (-273.15°C or -459.67°F).
Celsius and Fahrenheit are equal at -40 degrees. -40°C = -40°F, the only point where the two scales intersect.
Room temperature is typically considered to be between 20°C to 22°C (68°F to 72°F). This is the comfortable range for most indoor activities.
Meteorologists use temperature conversions when reporting weather in different regions. Understanding temperature scales is essential for weather forecasting, climate studies, and travel planning.
Recipes from different countries use different temperature scales. Our converter helps you convert oven temperatures, candy making temperatures, and food safety guidelines between Celsius and Fahrenheit.
Scientists use the Kelvin scale for experiments because it starts at absolute zero. Our converter helps students and researchers convert between Kelvin, Celsius, and Fahrenheit for their work.
Medical professionals use both Celsius and Fahrenheit for body temperature readings. Understanding fever thresholds in both scales is important for healthcare workers and patients.