From the practical point of view, a Fahrenheit to Celsius conversion is often needed when Americans want to use European recipes and cookbooks with domestic ovens that are graduated in degrees Fahrenheit.

## Temperature conversion

Why do we need a temperature conversion? Historically, countries utilizing Imperial measuring system
(feet, miles, yards, ounces, and pounds) measure temperatures in Fahrenheit. Celsius degrees, on the other hand,
are utilized in countries using the metric system (meters, kilometers, grams, and kilograms as opposed to imperial
measures). Converting degrees Fahrenheit to Celsius is simple: take the Fahrenheit number, subtract 32, and multiply by 5/9.
Converting Celsius to Fahrenheit is similarly easy, and requires multiplying the Celsius value by 9/5 and adding 32 degrees.

**ºC = (ºF - 32) * 5⁄9**

**ºF = ºC * 9⁄5 + 32**

## Fahrenheit to Celsius converter

So why do we need a computer to convert temperature measurement units? It’s just simpler and easier to have a valid Celsius conversion by pitting a number in Fahrenheit, click, and read a Celsius temperature in the output (or vice versa). Besides, there are more temperature units in the world than just Celsius and Fahrenheit! Temperatures can be measured in Kelvin, Rankine, Reaumur and some other units. This online temperature converter can handle these units and provide the result back in all of them in a single click and even without reloading a page!

## Celsius scale

Historically, different countries utilized different systems to measure temperatures. The Celsius temperature scale, also known as Centigrade, defines zero degrees as a freezing point of water, and one hundred degrees as a boiling point of water at normal atmosphere pressure at sea level. The Celsius scale and degrees centigrade are the most popular units of measuring temperature in everyday life. Celsius is the most prominent in countries using the metric system of measures.

## Fahrenheit scale

Countries employing the imperial system, such as the USA, use Fahrenheit, a different, older system of temperature units. The Fahrenheit scale places the freezing point of water (or melting point of ice in some texts) at 32 degrees Fahrenheit and the boiling point of water at 212 degrees Fahrenheit normal atmosphere pressure at sea level. Corresponding to the tradition of imperial measuring units, the Fahrenheit scale avoids using round numbers such as 10 or 100, having 180 degrees between the boiling and freezing points of water. Needless to say, the Fahrenheit scale is used strictly for non-scientific purposes such as referring to weather conditions. Most countries except the USA have adopted the more convenient Celsius system.

## Kelvin scale

The Kelvin temperature scale used for scientific purposes is based on the Celsius system. Placing the zero point at absolute zero as defined by thermodynamics as theoretical absence of all energy, zero degrees Kelvin is -273.15 degrees in Celsius. Kelvin and Celsius systems use the same units for defining temperature intervals, for which purposes one degree Kelvin equals one degree Celsius. Precise Celsius conversion is fairly easy by adding or subtracting 273.15 degrees.

## Rankine scale

For American scientists troubled with the Celsius-based system of Kelvin, a Rankine scale is still available. Defining the zero point as absolute zero (as the Kelvin scale does), the Rankine system uses degrees Fahrenheit instead of Celsius to describe temperature intervals. This system is still used in some engineering calculations and domestic scientific works of US scientists, although it is not recommended by the US NIST for using in publications. Celsius conversion works similarly to the Kelvin and Fahrenheit scales.

## Reaumur scale

Finally, the Reaumur scale sets freezing and boiling points of water at 0 and 80 degrees Reaumur correspondingly. Today, the Reaumur scale is mostly history.