Maths Formulas

Fahrenheit to Celsius Formula

To measure the temperature of any object we use a thermometer. Unit for measuring the temperature in Fahrenheit. Celsius and Kelvin. Although Fahrenheit has been replaced by the Celsius in most of the countries and for most applications. But still, this unit is used in many other applications by medical thermometer we are still measuring body temperature in Fahrenheit. U.S. meteorologists continue to use the Fahrenheit scale. In this topic, we will see its definition and formula of Fahrenheit to Celsius for conversion. Let us learn the interesting topic.

formula of fahrenheit to celsius

Fahrenheit to Celsius Formula

What is Fahrenheit?

Fahrenheit is a temperature scale that is based on the range of temperature of the boiling point of water at 212 and the freezing point at 32. Daniel Gabriel Fahrenheit has developed this scale, who was a German-born scientist but lived in the Netherlands. Nowadays this scale is used primarily in the United States and some Caribbean countries.

Fahrenheit developed the first modern thermometer in 1714. It was the mercury thermometer. Fahrenheit’s thermometer was based on the alcohol-based thermometer invented by Olaus Roemer, a Danish scientist. Roemer marked two points on his thermometer 0 as the lowest point and 60 as the temperature of boiling water.

Because the mercury thermometer was more accurate, so Fahrenheit decided to expand the Roemer scale by multiplying its values by four. He made adjustments to those metrics based on his research.

In his initial scale, the zero points were determined by placing the thermometer in an equal mix of ice, water, and ammonium chloride salt. This stable temperature was set as 0. Then the second point, at 32, was an equal mix of ice and water.

And the third point, 96, was the human body temperature and referred to as “blood-heat. The scale was recalibrated after the death of Fahrenheit by marking 32 and 212 as the exact melting and boiling points of plain water, minus the salt. It also makes the normal body temperature as 98.6 which has become the standard.

That change made Celsius-to-Fahrenheit conversions easier. The size of the Fahrenheit degree is \(\frac{5}{9}\) th of the size of the same unit on Celsius temperature scales. This makes it easier to do exact measurements without using fractions in the Fahrenheit scale.

The Formula for Conversion of Fahrenheit

As shown, there is a ratio of \(\frac{180}{100}\), or \(\frac{9}{5}\), between the Fahrenheit and Celsius scales. We have two different formulae in this regard.

  1. The standard formula from Celsius to Fahrenheit is:

\(T(in Fahrenheit)=\frac{9}{5}* T(in Celcius)+32 \)

  1. Also, the standard formula from Fahrenheit to Celsius is:

\(T(in Celcius)=\frac{5}{9}*[T(in Fahrenheit)-32]\)


  • Fahrenheit scale to Celsius scale: Subtract 32, then multiply by 5, then divide by 9
  • Celsius scale to Fahrenheit scale: Multiply by 9, divide by 5, then add 32

Solved Examples

Q.1:  An object is having the temperature of 440 C . Covert this temperature into the Fahrenheit scale.

Solution: Temperature in Fahrenheit is,

F = \(\frac{9}{5}\)*44 + 32

= (1.8 * 44) + 32

= 79.2 + 32

= 111.20  F

Q.2: An object is having the temperature 2120 F . Convert this temperature into Celsius scale:

Solution: Temperature in Celsius is,

C= \(\frac{5}{9}\)* (212-32)

= \(\frac{5}{9}\)* (180)

= 1000 C.

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One response to “Equation Formula”

  1. KUCKOO B says:

    I get a different answer for first example.
    I got Q1 as 20.5
    median 23 and
    Q3 26

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