Temperature is a measure of the average kinetic energy of particles in a substance. There are several temperature scales used around the world, with Celsius and Fahrenheit being the most common in everyday use, and Kelvin being the standard in scientific contexts.
The Fahrenheit scale is a thermodynamic temperature scale developed by German physicist Daniel Gabriel Fahrenheit in 1724. On this scale:
The Celsius scale, originally known as the centigrade scale, was developed by Swedish astronomer Anders Celsius in 1742. On this scale:
The Kelvin scale is the base unit of temperature in the International System of Units (SI). It is an absolute thermodynamic temperature scale:
The Rankine scale is less commonly used but is an absolute temperature scale based on the Fahrenheit scale:
Celsius = (Fahrenheit - 32) × 5/9 or Celsius = (Fahrenheit - 32) / 1.8
Fahrenheit = (Celsius × 9/5) + 32 or Fahrenheit = (Celsius × 1.8) + 32
Kelvin = Celsius + 273.15
Celsius = Kelvin - 273.15
Kelvin = (Fahrenheit - 32) × 5/9 + 273.15
Fahrenheit = (Kelvin - 273.15) × 9/5 + 32
Celsius = (Fahrenheit - 32) / 1.8Celsius = (32 - 32) / 1.8Celsius = 0 / 1.8Celsius = 0
Fahrenheit = (Celsius × 1.8) + 32Fahrenheit = (100 × 1.8) + 32Fahrenheit = 180 + 32Fahrenheit = 212
Kelvin = Celsius + 273.15Kelvin = 0 + 273.15Kelvin = 273.15
Fahrenheit to Celsius conversion is difficult to do in your head, but a rough °F to °C conversion is actually quite easy – just take 30 from the Fahrenheit value and then half it. This should be reasonably accurate for weather temperatures.
For example:
To convert Celsius to Fahrenheit approximately, double the Celsius value and add 30.
For example:
Fahrenheit and Celsius are the two most common temperature scales worldwide.
Developed by the German physicist Daniel Gabriel Fahrenheit in the early 1700s, Fahrenheit is widely used in the United States and, to a lesser extent, some other countries such as United Kingdom and Ireland. The freezing point of water is set at 32 degrees and the boiling point of water is set at 212 degrees.
Celsius, also known as Centigrade in some settings, is used in the majority of the world for temperature measurement. Created by Anders Celsius, a Swedish astronomer in the mid-1700s, the freezing point of water is denoted as 0 degrees C while the boiling point of water is 100 degrees C.
The Celsius scale is generally more globally accepted than the Fahrenheit scale. Despite this the Fahrenheit scale is still commonly used for weather forecasts, cooking, and everyday references in the United States of America.
| Temperature | Celsius | Fahrenheit | Kelvin | Description |
|---|---|---|---|---|
| Absolute Zero | -273.15°C | -459.67°F | 0 K | Theoretical temperature where all molecular motion stops |
| Liquid Nitrogen | -196°C | -321°F | 77 K | Common cryogenic coolant |
| Dry Ice (CO2) | -78.5°C | -109°F | 195 K | Solid carbon dioxide |
| Freezing Point of Water | 0°C | 32°F | 273.15 K | Standard reference point |
| Room Temperature | 20-25°C | 68-77°F | 293-298 K | Comfortable indoor temperature |
| Human Body Temperature | 37°C | 98.6°F | 310 K | Average human body temperature |
| Boiling Point of Water | 100°C | 212°F | 373.15 K | At standard atmospheric pressure |
| Water Gasification | 100°C | 212°F | 373.15 K | Steam formation |
Conversion between Fahrenheit to Celsius can be difficult because each of the temperature scales have different starting points and different increments between each degree.
On the Fahrenheit scale, the freezing point of water is at 32 degrees F and the boiling point of water at 212 degrees F. This means that there are 180 degrees between these two points. Celsius has the freezing point of water at 0 degrees C and the boiling point at 100 degrees C making the interval between the points 100 degrees.
The combination of these differences makes conversion between Fahrenheit to Celsius more complicated.
To convert Fahrenheit to Celsius, you must first subtract 32 from the Fahrenheit value and then divide the result by 1.8 (or 5/9). This conversion can make it difficult to mentally perform in you head without the use of a calculator or conversion chart such as the one provided on this page.
Additionally, the mathematical relationship between the scales is not intuitive for most people. Unlike simple conversions like inches to centimeters (which uses a straightforward multiplication factor), temperature conversions involve both a multiplication and an addition/subtraction component.
Recipes from different countries may use different temperature scales. Understanding conversions is essential for accurate cooking temperatures.
Scientists worldwide use the Celsius and Kelvin scales for consistency in research and data sharing.
When traveling or communicating internationally, understanding temperature conversions helps interpret weather forecasts and other temperature-related information.
Industrial processes often require precise temperature control, and equipment may be calibrated in different scales.
Medical devices and research may use different temperature scales depending on regional standards and scientific conventions.
When implementing temperature conversion in software, consider:
The development of temperature scales reflects the evolution of scientific understanding:
Understanding the history helps explain why these scales have their particular reference points and intervals.