Convert between Celsius, Fahrenheit, Kelvin, and other temperature units. Use the formulas, examples, and quick reference tables below for fast, accurate conversions.
Temperature is one of the most commonly measured quantities, yet different parts of the world use different temperature scales. Understanding these scales and how to convert between them is essential for travel, cooking, scientific work, and everyday life.
The Celsius scale, also known as centigrade, is the most widely used temperature scale worldwide. It's based on the properties of water: 0°C is the freezing point of water, and 100°C is the boiling point at standard atmospheric pressure. The Celsius scale is part of the metric system and is used in most countries for weather reporting, cooking, and scientific work.
The Celsius scale was developed by Swedish astronomer Anders Celsius in 1742. It's particularly useful because it's based on easily reproducible reference points (water's phase changes) and integrates well with the metric system's base-10 structure.
The Fahrenheit scale is primarily used in the United States, though it's also used in some Caribbean countries. It was developed by German physicist Daniel Gabriel Fahrenheit in 1724. On this scale, water freezes at 32°F and boils at 212°F at standard atmospheric pressure.
The Fahrenheit scale uses smaller degree increments than Celsius, which some people find more intuitive for weather temperatures. For example, the difference between 70°F and 71°F feels more noticeable than the difference between 21°C and 21.5°C, making Fahrenheit useful for describing comfortable temperature ranges.
Kelvin is the SI base unit for temperature and is used in scientific work worldwide. Unlike Celsius and Fahrenheit, Kelvin is an absolute temperature scale, meaning it starts at absolute zero (the theoretical point where all molecular motion stops). Absolute zero is 0 K, which equals -273.15°C.
The Kelvin scale is essential in physics, chemistry, and engineering because many physical laws and equations require absolute temperature. For example, the ideal gas law and thermodynamic equations use Kelvin. The scale uses the same degree size as Celsius, so a 1-degree change in Celsius equals a 1-degree change in Kelvin.
Celsius: Use for weather (outside the US), cooking (most recipes), scientific measurements, and international communication. It's the standard in most of the world.
Fahrenheit: Use for weather in the United States, some cooking recipes, and when communicating with American audiences. Many Americans find Fahrenheit more intuitive for describing comfortable temperatures.
Kelvin: Use for scientific calculations, physics problems, engineering applications, and any situation requiring absolute temperature. Never use "degrees" with Kelvin (it's just "Kelvin" or "K", not "degrees Kelvin").
Temperature conversions are different from most unit conversions because they involve both multiplication and addition/subtraction. This is because temperature scales have different zero points. For example, 0°C equals 32°F, not 0°F. Always use the complete conversion formulas rather than simple multiplication.
When converting temperature differences (like "the temperature increased by 10 degrees"), you can use simpler conversions. A 10°C increase equals an 18°F increase (multiply by 9/5), but this only works for temperature changes, not absolute temperatures.
To convert Celsius to Kelvin, add 273.15 to the Celsius value.
Celsius + 273.15 = Kelvin
Example: 25°C + 273.15 = 298.15 K
To convert Fahrenheit to Celsius, subtract 32 from the Fahrenheit value, then multiply by 5/9.
(Fahrenheit − 32) × 5/9 = Celsius
Example: (77°F − 32) × 5/9 = 25°C
(25 × 9/5) + 32 = 77°F
How do you convert Celsius to Kelvin?
Add 273.15 to the Celsius value. For example, 25°C + 273.15 = 298.15 K.
What is the formula for Fahrenheit to Celsius?
(°F − 32) × 5/9 = °C. For example, 77°F − 32 = 45, then 45 × 5/9 = 25°C.
How do you convert Celsius to Fahrenheit step by step?
Multiply the Celsius temperature by 9/5 and add 32. For example, (25 × 9/5) + 32 = 77°F.
What are common temperature units?
Celsius (°C), Fahrenheit (°F), and Kelvin (K) are commonly used for temperature measurement.
Temperature conversion involves transforming measurements between different temperature scales including Celsius, Fahrenheit, Kelvin, Rankine, Réaumur, Delisle, and Newton scales.
